- DNA and RNA belong to a class of macromolecules called nucleic acids.
- Nucleic acids are polynucleotides which means they contain many nucleotides joined together.
- A nucleotide consists of:
- One cyclic five-carbon sugar (The carbons found in this sugar are numbered 1' through to 5')
- One phosphate
- One nitrogenous base
- The sugar is deoxyribose in DNA and ribose in RNA. The only difference between the sugars is that ribose has a hydroxyl group (OH) on the 2' carbon and deoxyribose does not. This makes deoxyribose more stable than ribose.
- The phosphate is linked to the 5' carbon of the sugar in both RNA and DNA.
- The nitrogenous bases are adenine(A), guanine(G), cytosine(C), thymine(T), and uracil(U).
- Adenine and guanine are purines (contains a six membered ring of carbon and nitrogen fused to a five membered ring).
- Adenine and guanine are both found in DNA and RNA.
- Cytosine, thymine and uracil are pyrmidines (contains a six membered ring of carbon and nitrogen).
- Cytosine is found in both DNA and RNA, but thymine is only found in DNA and uracil is only found in RNA.
- A nucleotide is formed when a phosphate attahes to the 5' carbon of the sugar and one of the nitrogenous baseses attaches to the 1' carbon of the sugar.
- A strand of DNA or RNA consists of nucleotides linked together by phosphodiester bonds.
- A phosphodiester bond exists between the phosphate of one nucleotide and the sugar 3' carbon of the the next nucleotide.
- This forms a backbone of alternating sugar and phosphate molecules known as the "sugar-phosphate backbone".
- RNA, in most cases, consists of one strand of nucleic acids linked together by phosphodiester bonds.
- A DNA molecule consists of two strands of nucleotides twisted together to form a double helix.
- The sugar-phosphate backbone is found on the outside of this helix and the bases are found braching towards the middle.
- Hydrogen bonds join the the nitrogenous bases and hold the two strands together.
Monday, April 29, 2013
DNA and RNA Structure
DNA Micro Biology
Hi, and welcome to the DNA microbiology guide online.
This is a premium source of DNA and
related information, including several interesting videos, a bus load of
pictures and some very informative text about DNA. Not only do we have
information about microbiology, but we also feature articles on
virology, parasitology and more.
DNA Structure
During the 1950s, a tremendous explosion in biological research
occurred, and the methods of gene expression were elucidated. The
knowledge generated during this period helped explain how genes function
in microorganisms and gave rise to the science of molecular genetics.
This science is concerned with the activity of deoxyribonucleic acid
(DNA) and how that activity brings about the production of proteins in
microbial and other cells.
DNA Structure
During the 1950s, a tremendous explosion in biological research
occurred, and the methods of gene expression were elucidated. The
knowledge generated during this period helped explain how genes function
in microorganisms and gave rise to the science of molecular genetics.
This science is concerned with the activity of deoxyribonucleic acid
(DNA) and how that activity brings about the production of proteins in
microbial and other cells.
DNA Structure
During the 1950s, a tremendous explosion in biological research
occurred, and the methods of gene expression were elucidated. The
knowledge generated during this period helped explain how genes function
in microorganisms and gave rise to the science of molecular genetics.
This science is concerned with the activity of deoxyribonucleic acid
(DNA) and how that activity brings about the production of proteins in
microbial and other cells.
DNA Structure
During the 1950s, a tremendous explosion in biological research
occurred, and the methods of gene expression were elucidated. The
knowledge generated during this period helped explain how genes function
in microorganisms and gave rise to the science of molecular genetics.
This science is concerned with the activity of deoxyribonucleic acid
(DNA) and how that activity brings about the production of proteins in
microbial and other cells.
What is a cell?
Cells are the basic building blocks of all living things. The human
body is composed of trillions of cells. They provide structure for the
body, take in nutrients from food, convert those nutrients into energy,
and carry out specialized functions. Cells also contain the body’s
hereditary material and can make copies of themselves.
Cells have many parts, each with a different function. Some of these parts, called organelles, are specialized structures that perform certain tasks within the cell. Human cells contain the following major parts, listed in alphabetical order:
Cells have many parts, each with a different function. Some of these parts, called organelles, are specialized structures that perform certain tasks within the cell. Human cells contain the following major parts, listed in alphabetical order:
What is DNA?
DNA, or deoxyribonucleic acid, is the hereditary material in humans
and almost all other organisms. Nearly every cell in a person’s body has
the same DNA. Most DNA is located in the cell nucleus (where it is
called nuclear DNA), but a small amount of DNA can also be found in the
mitochondria (where it is called mitochondrial DNA or mtDNA).
The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.
An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.
The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.
An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.
arachnoid mater
The arachnoid mater is the middle of the
meningeal layers, and as its name implies, appears spider-like or more
specifically has the appearance of a spider web. The arachnoid mater
lies superior to the subarachnoid space, which is located between the
arachnoid membrane and the pia mater.
anterior longitudinal ligament
The anterior longitudinal ligament
consists of strong, dense fibers, located inside the bodies of the
vertebrae. They span nearly the whole length of the spine, beginning
with the second vertebrae (or axis), and extending to the sacrum. The
ligament is thicker in the middle (or thoracic region). Some of the
shorter fibers are separated by circular openings, which allow for the
passage of blood vessels.
Skeletal System Anatomy
The skeletal system in an adult body is made up of 206 individual bones. These bones are arranged into two major divisions: the axial skeleton and the appendicular skeleton. The axial skeleton runs along the body’s midline axis and is made up of 80 bones in the following regions:
The skull is composed of 22 bones that are fused together except for the mandible. These 21 fused bones are separate in children to allow the skull and brain to grow, but fuse to give added strength and protection as an adult. The mandible remains as a movable jaw bone and forms the only movable joint in the skull with the temporal bone.
The bones of the superior portion of the skull are known as the cranium and protect the brain from damage. The bones of the inferior and anterior portion of the skull are known as facial bones and support the eyes, nose, and mouth.
Hyoid and Auditory Ossicles
The hyoid is a small, U-shaped bone found just inferior to the mandible. The hyoid is the only bone in the body that does not form a joint with any other bone—it is a floating bone. The hyoid’s function is to help hold the trachea open and to form a bony connection for the tongue muscles.
The malleus, incus, and stapes—known collectively as the auditory ossicles—are the smallest bones in the body. Found in a small cavity inside of the temporal bone, they serve to transmit and amplify sound from the eardrum to the inner ear.
Vertebrae
Twenty-six vertebrae form the vertebral column of the human body. They are named by region:
Ribs and Sternum
The sternum, or breastbone, is a thin, knife-shaped bone located along the midline of the anterior side of the thoracic region of the skeleton. The sternum connects to the ribs by thin bands of cartilage called the costal cartilage.
There are 12 pairs of ribs that together with the sternum form the ribcage of the thoracic region. The first seven ribs are known as “true ribs” because they connect the thoracic vertebrae directly to the sternum through their own band of costal cartilage. Ribs 8, 9, and 10 all connect to the sternum through cartilage that is connected to the cartilage of the seventh rib, so we consider these to be “false ribs.” Ribs 11 and 12 are also false ribs, but are also considered to be “floating ribs” because they do not have any cartilage attachment to the sternum at all.
Pectoral Girdle and Upper Limb
The pectoral girdle connects the upper limb (arm) bones to the axial skeleton and consists of the left and right clavicles and left and right scapulae.
The humerus is the bone of the upper arm. It forms the ball and socket joint of the shoulder with the scapula and forms the elbow joint with the lower arm bones. The radius and ulna are the two bones of the forearm. The ulna is on the medial side of the forearm and forms a hinge joint with the humerus at the elbow. The radius allows the forearm and hand to turn over at the wrist joint.
The lower arm bones form the wrist joint with the carpals, a group of eight small bones that give added flexibility to the wrist. The carpals are connected to the five metacarpals that form the bones of the hand and connect to each of the fingers. Each finger has three bones known as phalanges, except for the thumb, which only has two phalanges.
Pelvic Girdle and Lower Limb
Formed by the left and right hip bones, the pelvic girdle connects the lower limb (leg) bones to the axial skeleton.
The femur is the largest bone in the body and the only bone of the thigh (femoral) region. The femur forms the ball and socket hip joint with the hip bone and forms the knee joint with the tibia and patella. Commonly called the kneecap, the patella is special because it is one of the few bones that are not present at birth. The patella forms in early childhood to support the knee for walking and crawling.
The tibia and fibula are the bones of the lower leg. The tibia is much larger than the fibula and bears almost all of the body’s weight. The fibula is mainly a muscle attachment point and is used to help maintain balance. The tibia and fibula form the ankle joint with the talus, one of the seven tarsal bones in the foot.
The tarsals are a group of seven small bones that form the posterior end of the foot and heel. The tarsals form joints with the five long metatarsals of the foot. Then each of the metatarsals forms a joint with one of the set of phalanges in the toes. Each toe has three phalanges, except for the big toe, which only has two phalanges.
Microscopic Structure of Bones
The skeleton makes up about 30-40% of an adult’s body mass. The skeleton’s mass is made up of nonliving bone matrix and many tiny bone cells. Roughly half of the bone matrix’s mass is water, while the other half is collagen protein and solid crystals of calcium carbonate and calcium phosphate.
Living bone cells are found on the edges of bones and in small cavities inside of the bone matrix. Although these cells make up very little of the total bone mass, they have several very important roles in the functions of the skeletal system. The bone cells allow bones to:
All of the bones of the body can be broken down into five types: long, short, flat, irregular, and sesamoid.
The long bones of the body contain many distinct regions due to the way in which they develop. At birth, each long bone is made of three individual bones separated by hyaline cartilage. Each end bone is called an epiphysis (epi = on; physis = to grow) while the middle bone is called a diaphysis (dia = passing through). The epiphyses and diaphysis grow towards one another and eventually fuse into one bone. The region of growth and eventual fusion in between the epiphysis and diaphysis is called the metaphysis (meta = after). Once the long bone parts have fused together, the only hyaline cartilage left in the bone is found as articular cartilage on the ends of the bone that form joints with other bones. The articular cartilage acts as a shock absorber and gliding surface between the bones to facilitate movement at the joint.
Looking at a bone in cross section, there are several distinct layered regions that make up a bone. The outside of a bone is covered in a thin layer of dense irregular connective tissue called the periosteum. The periosteum contains many strong collagen fibers that are used to firmly anchor tendons and muscles to the bone for movement. Stem cells and osteoblast cells in the periosteum are involved in the growth and repair of the outside of the bone due to stress and injury. Blood vessels present in the periosteum provide energy to the cells on the surface of the bone and penetrate into the bone itself to nourish the cells inside of the bone. The periosteum also contains nervous tissue and many nerve endings to give bone its sensitivity to pain when injured.
Deep to the periosteum is the compact bone that makes up the hard, mineralized portion of the bone. Compact bone is made of a matrix of hard mineral salts reinforced with tough collagen fibers. Many tiny cells called osteocytes live in small spaces in the matrix and help to maintain the strength and integrity of the compact bone.
Deep to the compact bone layer is a region of spongy bone where the bone tissue grows in thin columns called trabeculae with spaces for red bone marrow in between. The trabeculae grow in a specific pattern to resist outside stresses with the least amount of mass possible, keeping bones light but strong. Long bones have a spongy bone on their ends but have a hollow medullary cavity in the middle of the diaphysis. The medullary cavity contains red bone marrow during childhood, eventually turning into yellow bone marrow after puberty.
Articulations
An articulation, or joint, is a point of contact between bones, between a bone and cartilage, or between a bone and a tooth. Synovial joints are the most common type of articulation and feature a small gap between the bones. This gap allows a free range of motion and space for synovial fluid to lubricate the joint. Fibrous joints exist where bones are very tightly joined and offer little to no movement between the bones. Fibrous joints also hold teeth in their bony sockets. Finally, cartilaginous joints are formed where bone meets cartilage or where there is a layer of cartilage between two bones. These joints provide a small amount of flexibility in the joint due to the gel-like consistency of cartilage.
- Skull
- Hyoid
- Auditory ossicles
- Ribs
- Sternum
- Vertebral column
- Upper limbs
- Lower limbs
- Pelvic girdle
- Pectoral (shoulder) girdle
The skull is composed of 22 bones that are fused together except for the mandible. These 21 fused bones are separate in children to allow the skull and brain to grow, but fuse to give added strength and protection as an adult. The mandible remains as a movable jaw bone and forms the only movable joint in the skull with the temporal bone.
The bones of the superior portion of the skull are known as the cranium and protect the brain from damage. The bones of the inferior and anterior portion of the skull are known as facial bones and support the eyes, nose, and mouth.
Hyoid and Auditory Ossicles
The hyoid is a small, U-shaped bone found just inferior to the mandible. The hyoid is the only bone in the body that does not form a joint with any other bone—it is a floating bone. The hyoid’s function is to help hold the trachea open and to form a bony connection for the tongue muscles.
The malleus, incus, and stapes—known collectively as the auditory ossicles—are the smallest bones in the body. Found in a small cavity inside of the temporal bone, they serve to transmit and amplify sound from the eardrum to the inner ear.
Vertebrae
Twenty-six vertebrae form the vertebral column of the human body. They are named by region:
- Cervical (neck) - 7 vertebrae
- Thoracic (chest) - 12 vertebrae
- Lumbar (lower back) - 5 vertebrae
- Sacrum - 1 vertebra
- Coccyx (tailbone) - 1 vertebra
Ribs and Sternum
The sternum, or breastbone, is a thin, knife-shaped bone located along the midline of the anterior side of the thoracic region of the skeleton. The sternum connects to the ribs by thin bands of cartilage called the costal cartilage.
There are 12 pairs of ribs that together with the sternum form the ribcage of the thoracic region. The first seven ribs are known as “true ribs” because they connect the thoracic vertebrae directly to the sternum through their own band of costal cartilage. Ribs 8, 9, and 10 all connect to the sternum through cartilage that is connected to the cartilage of the seventh rib, so we consider these to be “false ribs.” Ribs 11 and 12 are also false ribs, but are also considered to be “floating ribs” because they do not have any cartilage attachment to the sternum at all.
Pectoral Girdle and Upper Limb
The pectoral girdle connects the upper limb (arm) bones to the axial skeleton and consists of the left and right clavicles and left and right scapulae.
The humerus is the bone of the upper arm. It forms the ball and socket joint of the shoulder with the scapula and forms the elbow joint with the lower arm bones. The radius and ulna are the two bones of the forearm. The ulna is on the medial side of the forearm and forms a hinge joint with the humerus at the elbow. The radius allows the forearm and hand to turn over at the wrist joint.
The lower arm bones form the wrist joint with the carpals, a group of eight small bones that give added flexibility to the wrist. The carpals are connected to the five metacarpals that form the bones of the hand and connect to each of the fingers. Each finger has three bones known as phalanges, except for the thumb, which only has two phalanges.
Pelvic Girdle and Lower Limb
Formed by the left and right hip bones, the pelvic girdle connects the lower limb (leg) bones to the axial skeleton.
The femur is the largest bone in the body and the only bone of the thigh (femoral) region. The femur forms the ball and socket hip joint with the hip bone and forms the knee joint with the tibia and patella. Commonly called the kneecap, the patella is special because it is one of the few bones that are not present at birth. The patella forms in early childhood to support the knee for walking and crawling.
The tibia and fibula are the bones of the lower leg. The tibia is much larger than the fibula and bears almost all of the body’s weight. The fibula is mainly a muscle attachment point and is used to help maintain balance. The tibia and fibula form the ankle joint with the talus, one of the seven tarsal bones in the foot.
The tarsals are a group of seven small bones that form the posterior end of the foot and heel. The tarsals form joints with the five long metatarsals of the foot. Then each of the metatarsals forms a joint with one of the set of phalanges in the toes. Each toe has three phalanges, except for the big toe, which only has two phalanges.
Microscopic Structure of Bones
The skeleton makes up about 30-40% of an adult’s body mass. The skeleton’s mass is made up of nonliving bone matrix and many tiny bone cells. Roughly half of the bone matrix’s mass is water, while the other half is collagen protein and solid crystals of calcium carbonate and calcium phosphate.
Living bone cells are found on the edges of bones and in small cavities inside of the bone matrix. Although these cells make up very little of the total bone mass, they have several very important roles in the functions of the skeletal system. The bone cells allow bones to:
- Grow and develop
- Be repaired following an injury or daily wear
- Be broken down to release their stored minerals
All of the bones of the body can be broken down into five types: long, short, flat, irregular, and sesamoid.
- Long. Long bones are longer than they are wide and are the
major bones of the limbs. Long bones grow more than the other classes of
bone throughout childhood and so are responsible for the bulk of our
height as adults. A hollow medullary cavity is found in the center of
long bones and serves as a storage area for bone marrow. Examples of
long bones include the femur, tibia, fibula, metatarsals, and phalanges.
- Short. Short bones are about as long as they are wide and
are often cubed or round in shape. The carpal bones of the wrist and the
tarsal bones of the foot are examples of short bones.
- Flat. Flat bones vary greatly in size and shape, but have
the common feature of being very thin in one direction. Because they are
thin, flat bones do not have a medullary cavity like the long bones.
The frontal, parietal, and occipital bones of the cranium—along with the ribs and hip bones—are all examples of flat bones.
- Irregular. Irregular bones have a shape that does not fit
the pattern of the long, short, or flat bones. The vertebrae, sacrum,
and coccyx of the spine—as well as the sphenoid, ethmoid, and zygomatic bones of the skull—are all irregular bones.
- Sesamoid. The sesamoid bones are formed after birth inside of tendons that run across joints. Sesamoid bones grow to protect the tendon from stresses and strains at the joint and can help to give a mechanical advantage to muscles pulling on the tendon. The patella and the pisiform bone of the carpals are the only sesamoid bones that are counted as part of the 206 bones of the body. Other sesamoid bones can form in the joints of the hands and feet, but are not present in all people.
The long bones of the body contain many distinct regions due to the way in which they develop. At birth, each long bone is made of three individual bones separated by hyaline cartilage. Each end bone is called an epiphysis (epi = on; physis = to grow) while the middle bone is called a diaphysis (dia = passing through). The epiphyses and diaphysis grow towards one another and eventually fuse into one bone. The region of growth and eventual fusion in between the epiphysis and diaphysis is called the metaphysis (meta = after). Once the long bone parts have fused together, the only hyaline cartilage left in the bone is found as articular cartilage on the ends of the bone that form joints with other bones. The articular cartilage acts as a shock absorber and gliding surface between the bones to facilitate movement at the joint.
Looking at a bone in cross section, there are several distinct layered regions that make up a bone. The outside of a bone is covered in a thin layer of dense irregular connective tissue called the periosteum. The periosteum contains many strong collagen fibers that are used to firmly anchor tendons and muscles to the bone for movement. Stem cells and osteoblast cells in the periosteum are involved in the growth and repair of the outside of the bone due to stress and injury. Blood vessels present in the periosteum provide energy to the cells on the surface of the bone and penetrate into the bone itself to nourish the cells inside of the bone. The periosteum also contains nervous tissue and many nerve endings to give bone its sensitivity to pain when injured.
Deep to the periosteum is the compact bone that makes up the hard, mineralized portion of the bone. Compact bone is made of a matrix of hard mineral salts reinforced with tough collagen fibers. Many tiny cells called osteocytes live in small spaces in the matrix and help to maintain the strength and integrity of the compact bone.
Deep to the compact bone layer is a region of spongy bone where the bone tissue grows in thin columns called trabeculae with spaces for red bone marrow in between. The trabeculae grow in a specific pattern to resist outside stresses with the least amount of mass possible, keeping bones light but strong. Long bones have a spongy bone on their ends but have a hollow medullary cavity in the middle of the diaphysis. The medullary cavity contains red bone marrow during childhood, eventually turning into yellow bone marrow after puberty.
Articulations
An articulation, or joint, is a point of contact between bones, between a bone and cartilage, or between a bone and a tooth. Synovial joints are the most common type of articulation and feature a small gap between the bones. This gap allows a free range of motion and space for synovial fluid to lubricate the joint. Fibrous joints exist where bones are very tightly joined and offer little to no movement between the bones. Fibrous joints also hold teeth in their bony sockets. Finally, cartilaginous joints are formed where bone meets cartilage or where there is a layer of cartilage between two bones. These joints provide a small amount of flexibility in the joint due to the gel-like consistency of cartilage.
Skeletal System Physiology
Bioscience Collection
The mission of Bioscience Collection is to provide collections of
plants, mammals, birds, reptiles and amphibians, insects and mollusks
that represent the natural history of New Mexico and southwestern North
America (United States and Mexico), and to serve as a safe repository
for in-house research specimens. These collections are used for
education, research and exhibits. We also have an extensive photographic
slide collection of New Mexico plants and birds. The staff consists
of one curator, a collection manager and seven dedicated volunteers.
As of 2011, the approximate numbers of catalogued specimens in each of the collections are as follows: Mammals 6,200, Birds 400, Arthropods 6,000, Mollusks 13,500, Reptiles and Amphibians 50, and Plants 3,100.
The majority of biological specimens are voucher specimens resulting from research (mammals and mollusks) conducted by Museum staff. The bird collection consists entirely of salvage specimens. Museum staff and volunteers have collected and developed the plant collection. The insect collection is primarily donated collections from various Museum and non-Museum researchers. The mollusk collection consists of several donated collections and Museum staff research collections. We also house frozen tissue of mammals, birds and mollusks for genetic study.
There have been approximately 20 publications in peer-reviewed journals and one NMMNH Bulletin published on specimens in the Collection.
As of 2011, the approximate numbers of catalogued specimens in each of the collections are as follows: Mammals 6,200, Birds 400, Arthropods 6,000, Mollusks 13,500, Reptiles and Amphibians 50, and Plants 3,100.
The majority of biological specimens are voucher specimens resulting from research (mammals and mollusks) conducted by Museum staff. The bird collection consists entirely of salvage specimens. Museum staff and volunteers have collected and developed the plant collection. The insect collection is primarily donated collections from various Museum and non-Museum researchers. The mollusk collection consists of several donated collections and Museum staff research collections. We also house frozen tissue of mammals, birds and mollusks for genetic study.
There have been approximately 20 publications in peer-reviewed journals and one NMMNH Bulletin published on specimens in the Collection.
Our History
Harvard Bioscience is a global developer, manufacturer and marketer of a broad range of specialized products,
primarily apparatus and scientific instruments used to advance life science research and regenerative medicine.
It started in the basement... Harvard(1) Bioscience was founded in 1901. Frustrated by the poor quality of equipment then available, Dr. William T. Porter began manufacturing his own high quality physiology teaching equipment in the basement of the Harvard Medical School. Dr. Porter went on to found the American Journal of Physiology and became one of the leading physiologists of his day. His equipment gained an enviable reputation for quality and reliability and began to be known simply as the Harvard Apparatus. The name stuck.
In the early 1980's the company started using the name Harvard Bioscience and in 2000 we officially changed the name of the company to Harvard Bioscience, Inc. In 1996 the current management team took over the company and expanded the product offering and improved growth and profitability. We completed our initial public offering in December 2000.
Both we and physiology have come a long way in 100 years. Today we are a leading worldwide supplier of scientific instruments used to improve life science research. Our products are used across a broad spectrum of both well established and cutting edge applications and are used by the world’s top pharmaceutical and biotech companies.
Our products are typically highly specialized for particular research applications in molecular, cellular, and physiology research. Our products are typically well-established in fairly mature markets with good, but not spectacular, growth rates.
Our brands are typically well-established names that convey quality, consistency and reassurance to scientists concerned about getting the highest quality data from their research. Our brands are often leaders in their niches. These brands include: Harvard Apparatus, Biochrom, Hoefer, Panlab, Warner Instruments, KD Scientific, Hugo Sachs Elektronik, BTX, and Denville Scientific.
Our distribution channels are as well-established as our brands and are intended to give us broad access to scientists across the globe. We sell our products to thousands of researchers in over 100 countries through our full-line catalog (and various other specialty catalogs), our websites and through distributors, including GE Healthcare, Thermo Fisher Scientific and VWR.
(1) Harvard is a registered trademark of Harvard University. The marks Harvard Apparatus and Harvard Bioscience are being used pursuant to a license agreement between Harvard University and Harvard Bioscience, Inc.
It started in the basement... Harvard(1) Bioscience was founded in 1901. Frustrated by the poor quality of equipment then available, Dr. William T. Porter began manufacturing his own high quality physiology teaching equipment in the basement of the Harvard Medical School. Dr. Porter went on to found the American Journal of Physiology and became one of the leading physiologists of his day. His equipment gained an enviable reputation for quality and reliability and began to be known simply as the Harvard Apparatus. The name stuck.
In the early 1980's the company started using the name Harvard Bioscience and in 2000 we officially changed the name of the company to Harvard Bioscience, Inc. In 1996 the current management team took over the company and expanded the product offering and improved growth and profitability. We completed our initial public offering in December 2000.
Both we and physiology have come a long way in 100 years. Today we are a leading worldwide supplier of scientific instruments used to improve life science research. Our products are used across a broad spectrum of both well established and cutting edge applications and are used by the world’s top pharmaceutical and biotech companies.
Our products are typically highly specialized for particular research applications in molecular, cellular, and physiology research. Our products are typically well-established in fairly mature markets with good, but not spectacular, growth rates.
Our brands are typically well-established names that convey quality, consistency and reassurance to scientists concerned about getting the highest quality data from their research. Our brands are often leaders in their niches. These brands include: Harvard Apparatus, Biochrom, Hoefer, Panlab, Warner Instruments, KD Scientific, Hugo Sachs Elektronik, BTX, and Denville Scientific.
Our distribution channels are as well-established as our brands and are intended to give us broad access to scientists across the globe. We sell our products to thousands of researchers in over 100 countries through our full-line catalog (and various other specialty catalogs), our websites and through distributors, including GE Healthcare, Thermo Fisher Scientific and VWR.
(1) Harvard is a registered trademark of Harvard University. The marks Harvard Apparatus and Harvard Bioscience are being used pursuant to a license agreement between Harvard University and Harvard Bioscience, Inc.
stability testing
Demonstration of the stability of an active pharmaceutical
ingredient is an essential component in the development and
commercialization of biopharmaceutical products.
Charles River Biopharmaceutical Services (BPS) performs stability studies for biopharmaceutical and pharmaceutical products and drug substances at all stages of the registration process. We have considerable experience designing and conducting testing programs to support early development, formal submission studies to the International Conference on Harmonisation (ICH) guidelines and commitment studies for the continued marketing of existing drug products. This experience has been gained through more than 15 years of stability testing for clients and successful support of their product applications.
Fully mapped and monitored storage facilities are available for the complete range of ICH conditions plus the sub-ambient conditions of -20°C, -30°C, -70°C and -80°C more suitable for biological products.
Studies are conducted according to current Good Manufacturing Practice (cGMP) guidelines. BPS has been approved as a named laboratory on multiple product licenses by the US Food and Drug Administration (FDA), US Department of Agriculture (USDA) and European regulatory authorities.
Charles River Biopharmaceutical Services (BPS) performs stability studies for biopharmaceutical and pharmaceutical products and drug substances at all stages of the registration process. We have considerable experience designing and conducting testing programs to support early development, formal submission studies to the International Conference on Harmonisation (ICH) guidelines and commitment studies for the continued marketing of existing drug products. This experience has been gained through more than 15 years of stability testing for clients and successful support of their product applications.
Fully mapped and monitored storage facilities are available for the complete range of ICH conditions plus the sub-ambient conditions of -20°C, -30°C, -70°C and -80°C more suitable for biological products.
Studies are conducted according to current Good Manufacturing Practice (cGMP) guidelines. BPS has been approved as a named laboratory on multiple product licenses by the US Food and Drug Administration (FDA), US Department of Agriculture (USDA) and European regulatory authorities.
residual DNA detection
The detection and quantification of minute amounts of residual
host cell DNA can be accomplished using any one of three highly
sensitive, validated methods. These methods encompass the entire range
of residual DNA from nonspecific detection of total DNA to highly
specific detection of single target sequences. The methods used are:
-
The ThresholdTM System from Molecular Devices® uses DNA binding proteins with high affinity for single-stranded DNA for nonspecific quantification of total DNA.
-
A hybridization-based method for the detection of the specific DNA of defined origin with dot blots and hybridization of radioisotope-labeled DNA probes uses random hexamers to generate representative probes covering the whole genome of the host cells.
-
A quantitative PCR-based method for the detection of specific DNA of defined origin targets a specific gene sequence for amplification and is calibrated using purified, species-matched, genomic DNA.
molecular biology
Detailed characterization of nucleic acid products is an essential
part of the development program for recombinant products. A
comprehensive array of analytical services to support this
characterization is available at Charles River Biopharmaceutical
Services (BPS). These methods are applied to determine the genetic
stability of recombinant products and for the characterization of
plasmid products.
Genetic Stability Testing
The genetic stability of recombinant cell lines needs to be demonstrated according to regulatory guidelines. The identity and integrity of recombinant genes has to be verified and shown to be stable throughout the production process. Stability is supported by characterization studies of cells at the end of production and comparing those attributes to those of the master cell bank. Identity may be addressed by DNA sequencing and comparing the results to a reference sequence. Genetic integrity is often confirmed by restriction enzyme analysis followed by Southern blotting and comparing the resulting fragment sizes to the expected sizes.
Determination of Copy Number
Genetically modified cell banks are characterized to quantify the number of copies of a recombinant gene or plasmid. Charles River has experience performing these types of studies on animal, bacterial and yeast cell banks. Both quantitative Southern blot analysis and quantitative PCR can be used to determine the copy number of one or more target sequences.
DNA Sequencing
BPS offers validated, current Good Manufacturing Practice (cGMP)-compliant DNA sequencing of recombinant gene constructs, plasmids and viruses. Sequencing can be accomplished using either the LiCORTM or Applied Biosystems DNA sequencing systems. Both systems provide at least two-fold, and in some cases three-fold, coverage on each DNA strand to ensure accuracy.
The extensive experience of Charles River with sample purification and preparation enables us to analyze samples in many different matrices. Samples are generally tested with and without the addition of known, small amounts of genomic DNA (“spikes”) to detect and control for potential interference.
Genetic Stability Testing
The genetic stability of recombinant cell lines needs to be demonstrated according to regulatory guidelines. The identity and integrity of recombinant genes has to be verified and shown to be stable throughout the production process. Stability is supported by characterization studies of cells at the end of production and comparing those attributes to those of the master cell bank. Identity may be addressed by DNA sequencing and comparing the results to a reference sequence. Genetic integrity is often confirmed by restriction enzyme analysis followed by Southern blotting and comparing the resulting fragment sizes to the expected sizes.
Determination of Copy Number
Genetically modified cell banks are characterized to quantify the number of copies of a recombinant gene or plasmid. Charles River has experience performing these types of studies on animal, bacterial and yeast cell banks. Both quantitative Southern blot analysis and quantitative PCR can be used to determine the copy number of one or more target sequences.
DNA Sequencing
BPS offers validated, current Good Manufacturing Practice (cGMP)-compliant DNA sequencing of recombinant gene constructs, plasmids and viruses. Sequencing can be accomplished using either the LiCORTM or Applied Biosystems DNA sequencing systems. Both systems provide at least two-fold, and in some cases three-fold, coverage on each DNA strand to ensure accuracy.
The extensive experience of Charles River with sample purification and preparation enables us to analyze samples in many different matrices. Samples are generally tested with and without the addition of known, small amounts of genomic DNA (“spikes”) to detect and control for potential interference.
endotoxin & pyrogenicity
Endotoxin and pyrogen detection is vital step for you to
gain market approval for your product. Charles River Biopharmaceutical
Services (BPS) offers this service as part of our process manufacturing
support network.
Endotoxin Testing
Our in vitro bacterial endotoxin testing, including gel-clot (qualitative), kinetic turbidimetric and chromogenic methods (quantitative), are carried out to meet all pharmacopoeia requirements. We provide preliminary screening and validation of products as well as a backup technical service. Test results are available within one to three days.
In addition, our Endotoxin and Microbial Detection group offers a line of rapid testing systems, which includes assays for fast and easy endotoxin analysis, glucan contamination, Gram determination and protein concentration.
Pyrogenicity Testing
We have extensive experience conducting in vivo pyrogenicity testing. To support this testing, newly refurbished, dedicated, pyrogen testing facilities are available.
Monocyte Activation Test
The monocyte activation test (MAT) is used to detect or quantify substances that activate human monocytes or monocytic cells to release endogenous mediators. It has been added to the portfolio offered by BPS following the recent changes to the European Pharmacopeia monograph (04/2010:20630). Charles River offers the assessment of pyrogenicity by quantifying the release of IL-1β from cryopreserved human blood (ELISA). A panel of cytokines, including tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6) and interleukin-8 (IL-8), can also be included for assessment.
Endotoxin Testing
Our in vitro bacterial endotoxin testing, including gel-clot (qualitative), kinetic turbidimetric and chromogenic methods (quantitative), are carried out to meet all pharmacopoeia requirements. We provide preliminary screening and validation of products as well as a backup technical service. Test results are available within one to three days.
In addition, our Endotoxin and Microbial Detection group offers a line of rapid testing systems, which includes assays for fast and easy endotoxin analysis, glucan contamination, Gram determination and protein concentration.
Pyrogenicity Testing
We have extensive experience conducting in vivo pyrogenicity testing. To support this testing, newly refurbished, dedicated, pyrogen testing facilities are available.
Monocyte Activation Test
The monocyte activation test (MAT) is used to detect or quantify substances that activate human monocytes or monocytic cells to release endogenous mediators. It has been added to the portfolio offered by BPS following the recent changes to the European Pharmacopeia monograph (04/2010:20630). Charles River offers the assessment of pyrogenicity by quantifying the release of IL-1β from cryopreserved human blood (ELISA). A panel of cytokines, including tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6) and interleukin-8 (IL-8), can also be included for assessment.
host cell protein assay
One of the objectives in designing a downstream process for
biopharmaceutical products is to remove any possible contaminating
proteins, including host cell proteins (HCPs). HCPs can still be present
at significant concentrations following several purification steps and
can even be co-purified and concentrated with the drug substance itself.
Multiple purification steps may be needed to remove HCPs,
however, each purification step also has the potential for additional
loss of product. Therefore, during the development of a downstream
process, suitable assays must be available to determine both the
concentration of the product and the amount of HCP present.
The type of assay required to determine HCP concentration is dependent upon the phase of product development. In the early process development phase as well as in early clinical phases, generic assays are normally acceptable. Charles River offers generic host cell protein assays for E. coli and CHO-derived products. These assays have been developed and validated on a generic sample matrix. They may be useful in the early stages of process development for a general investigation into HCP burden. Additionally, kits on any kind of cell systems may be used and adapted for a client matrix as well.
However, once the biopharmaceutical is used in clinical phase III studies, a validated, product-specific HCP assay is normally required. We have developed many specific assays on different cell matrices to quantify HCP using either ILA or ELISA. Assay development starts with testing for a suitable, specific antigen which has been produced by our client. This antigen will be used to immunize the animals from which the antisera will be obtained. After purification and qualification of the antibodies, a specific detection system is developed and optimized for the specific matrix. According to regulatory authorities, the assay should be validated prior to use in the quality control of a biopharmaceutical. The development and validation of a client-specific HCP assay normally requires between six and twelve months. Therefore, development of the assay should begin as soon as the downstream process development has been finalized.
The type of assay required to determine HCP concentration is dependent upon the phase of product development. In the early process development phase as well as in early clinical phases, generic assays are normally acceptable. Charles River offers generic host cell protein assays for E. coli and CHO-derived products. These assays have been developed and validated on a generic sample matrix. They may be useful in the early stages of process development for a general investigation into HCP burden. Additionally, kits on any kind of cell systems may be used and adapted for a client matrix as well.
However, once the biopharmaceutical is used in clinical phase III studies, a validated, product-specific HCP assay is normally required. We have developed many specific assays on different cell matrices to quantify HCP using either ILA or ELISA. Assay development starts with testing for a suitable, specific antigen which has been produced by our client. This antigen will be used to immunize the animals from which the antisera will be obtained. After purification and qualification of the antibodies, a specific detection system is developed and optimized for the specific matrix. According to regulatory authorities, the assay should be validated prior to use in the quality control of a biopharmaceutical. The development and validation of a client-specific HCP assay normally requires between six and twelve months. Therefore, development of the assay should begin as soon as the downstream process development has been finalized.
molecular biology
Detailed characterization of nucleic acid products is an essential
part of the development program for recombinant products. A
comprehensive array of analytical services to support this
characterization is available at Charles River Biopharmaceutical
Services (BPS). These methods are applied to determine the genetic
stability of recombinant products and for the characterization of
plasmid products.
Genetic Stability Testing
The genetic stability of recombinant cell lines needs to be demonstrated according to regulatory guidelines. The identity and integrity of recombinant genes has to be verified and shown to be stable throughout the production process. Stability is supported by characterization studies of cells at the end of production and comparing those attributes to those of the master cell bank. Identity may be addressed by DNA sequencing and comparing the results to a reference sequence. Genetic integrity is often confirmed by restriction enzyme analysis followed by Southern blotting and comparing the resulting fragment sizes to the expected sizes.
Determination of Copy Number
Genetically modified cell banks are characterized to quantify the number of copies of a recombinant gene or plasmid. Charles River has experience performing these types of studies on animal, bacterial and yeast cell banks. Both quantitative Southern blot analysis and quantitative PCR can be used to determine the copy number of one or more target sequences.
DNA Sequencing
BPS offers validated, current Good Manufacturing Practice (cGMP)-compliant DNA sequencing of recombinant gene constructs, plasmids and viruses. Sequencing can be accomplished using either the LiCORTM or Applied Biosystems DNA sequencing systems. Both systems provide at least two-fold, and in some cases three-fold, coverage on each DNA strand to ensure accuracy.
The extensive experience of Charles River with sample purification and preparation enables us to analyze samples in many different matrices. Samples are generally tested with and without the addition of known, small amounts of genomic DNA (“spikes”) to detect and control for potential interference.
Genetic Stability Testing
The genetic stability of recombinant cell lines needs to be demonstrated according to regulatory guidelines. The identity and integrity of recombinant genes has to be verified and shown to be stable throughout the production process. Stability is supported by characterization studies of cells at the end of production and comparing those attributes to those of the master cell bank. Identity may be addressed by DNA sequencing and comparing the results to a reference sequence. Genetic integrity is often confirmed by restriction enzyme analysis followed by Southern blotting and comparing the resulting fragment sizes to the expected sizes.
Determination of Copy Number
Genetically modified cell banks are characterized to quantify the number of copies of a recombinant gene or plasmid. Charles River has experience performing these types of studies on animal, bacterial and yeast cell banks. Both quantitative Southern blot analysis and quantitative PCR can be used to determine the copy number of one or more target sequences.
DNA Sequencing
BPS offers validated, current Good Manufacturing Practice (cGMP)-compliant DNA sequencing of recombinant gene constructs, plasmids and viruses. Sequencing can be accomplished using either the LiCORTM or Applied Biosystems DNA sequencing systems. Both systems provide at least two-fold, and in some cases three-fold, coverage on each DNA strand to ensure accuracy.
The extensive experience of Charles River with sample purification and preparation enables us to analyze samples in many different matrices. Samples are generally tested with and without the addition of known, small amounts of genomic DNA (“spikes”) to detect and control for potential interference.
DNA in Saliva with Oragene
The Oragene self-collection kit for DNA from saliva from DNA Genotek,
Inc. provides an all-in-one system for the collection,
stabilization, and transportation of DNA from saliva. Blood samples are
invasive to collect, as well as complex and costly to ship, store and
process. Buccal swabs provide a low quality and quantity of DNA.
Eliminate these challenges by collecting superior samples with the Oragene sample collection product line.
Eliminate these challenges by collecting superior samples with the Oragene sample collection product line.
- Easy collection, transportation and processing
- Painless, non-invasive collection of high-quality, high-quantity DNA
- DNA is stable for years at ambient temperature
- Proven on downstream applications
Difference Between Gene and Allele
A gene is a part of the DNA.
Alleles on the other hand refer to different versions of the same gene.
There are other more subtle differences between the two and this is
what we are going to explore on this page:
- Genes are the different parts of the DNA that decide the genetic traits a person is going to have. Alleles are the different sequences on the DNA-they determine a single characteristic in an individual.
- Another important difference between the two is that alleles occur in pairs. They are also differentiated into recessive and dominant categories. Genes do not have any such differentiation.
- An interesting difference between alleles and genes is that alleles produce opposite phenotypes that are contrasting by nature. When the two partners of a gene are homogeneous in nature, they are called homozygous. However, if the pair consists of different alleles, they are called heterozygous. In heterozygous alleles, the dominant allele gains an expression.
- The dominance of a gene is determined by whether the AA and Aa are alike phenotypically. It is easier to find dominants because they express themselves better when they are paired with either allele.
- Alleles are basically different types of the same gene. Let’s explain this to you in this way- If your eye color was decided by a single gene, the color blue would be carried by one allele and the color green by another. Fascinating, isn’t it?
- All of us inherit a pair of genes from each of our parents. These genes are exactly the same for each other. So what causes the differences between individuals? It is the result of the alleles.
- The difference between the two becomes more pronounced in the case of traits. A trait refers to what you see, so it is the physical expression of the genes themselves. Alleles determine the different versions of the genes that we see. A gene is like a machine that has been put together. However, how it will works will depend on the alleles.
Both alleles and genes play an all
important role in the development of living forms. The difference is
most colorfully manifest in humans of course! So next time you see the
variety of hair color and eye color around you, take a moment and admire
the phenomenal power of both the gene and the allele!
Summary:
1. Genes are something we inherit from our parents- alleles determine how they are expressed in an individual.
2. Alleles occur in pairs but there is no such pairing for genes.
3. A pair of alleles produces opposing phenotypes. No such generalization can be assigned to genes.
4. Alleles determine the traits we inherit.
5. The genes we inherit are the same for all humans. However, how these manifest themselves is actually determined by alleles!
1. Genes are something we inherit from our parents- alleles determine how they are expressed in an individual.
2. Alleles occur in pairs but there is no such pairing for genes.
3. A pair of alleles produces opposing phenotypes. No such generalization can be assigned to genes.
4. Alleles determine the traits we inherit.
5. The genes we inherit are the same for all humans. However, how these manifest themselves is actually determined by alleles!
Difference Between DNA and Genes
The terms gene and DNA are often used to
mean the same. However, in reality, they stand for very different
things. So, next time you want to blame your baldness on your father and
don’t know whether to berate your genes or your DNA, take a look at the
differences below:
DNA stands for deoxyribonucleic acid. This is the chain of ‘links’ that determines how the different cells
in your body will function. Each of these links is called a nucleotide.
DNA basically contains two copies of 23 chromosomes each, one from the
mother and one from the father of the person. Only some of these
complex cells carry the ‘genetic information for your genes. These are
the parts that decide what you basically inherit from your parents. This
makes genes only a subset of the DNA.
Your genes define the fundamental traits
you will inherit from your parents. They are parts of the DNA that
determine how the cells are going to live and function. They are special
colonies of nucleotides that decide how proteins are going to carry on
the process of building and reproducing in your body. All living things
depend on their genes to determine how they are going to develop in
their lives and how they, in turn are going to pass on their genetic
traits to their offspring.
For instance, if you thought about the
human body as a book that contained only DNA, the genes would be the
chapter containing instructions on how to make proteins and assist in
cell production. The other chapters may contain other details like where
the cells should start producing new proteins etc.
The DNA is like an instruction
booklet that determines the traits you are likely to get. The entire DNA
in a human body is packaged in the form of chromosomes. Each of these chromosomes
has definite characters that will determine a particular trait. This
includes such details like your hair color and the color of your eyes.
Each of these chapters that contain the codes for a particular trait is
known as a gene. So, if you are confused, just think about the gene as a
small piece of the total DNA that holds information about a particular
trait you have.
The study of genetics has gained
widespread acclaim in recent times. However, it was only with the
discovery of the DNA that a scientific basis for the genes we inherit
was established.
Both DNA and genes are the most basic
building blocks of your body. They determine how your cells are going to
behave throughout your life. Now you know who to thank for those
brains!
Summary:
1.  Genes are a part of the DNA.
2. Genes determine the traits you will inherit from your parents, DNA determines a lot more.
3. Genes have been studied for a long time now. The study of DNA is a relatively recent development.
1.  Genes are a part of the DNA.
2. Genes determine the traits you will inherit from your parents, DNA determines a lot more.
3. Genes have been studied for a long time now. The study of DNA is a relatively recent development.
Human genetic variation
Human genetic variation is the genetic differences both within and among populations. There may be multiple variants of any given gene in the human population (genes), leading to polymorphism. Many genes are not polymorphic, meaning that only a single allele is present in the population: the gene is then said to be fixed.[1]
No two humans are genetically identical. Even monozygotic twins, who develop from one zygote, have infrequent genetic differences due to mutations occurring during development and gene copy number variation.[2] Differences between individuals, even closely related individuals, are the key to techniques such as genetic fingerprinting. Alleles occur at different frequencies in different human populations, with populations that are more geographically and ancestrally remote tending to differ more.
Causes of differences between individuals include the exchange of genes during meiosis and various mutational events. There are at least two reasons why genetic variation exists between populations. Natural selection may confer an adaptive advantage to individuals in a specific environment if an allele provides a competitive advantage. Alleles under selection are likely to occur only in those geographic regions where they confer an advantage. The second main cause of genetic variation is due to the high degree of neutrality of most mutations. Most mutations do not appear to have any selective effect one way or the other on the organism. The main cause is genetic drift, this is the effect of random changes in the gene pool. In humans, founder effect and past small population size (increasing the likelihood of genetic drift) may have had an important influence in neutral differences between populations. The theory that humans recently migrated out of Africa supports this.
The study of human genetic variation has both evolutionary significance and medical applications. It can help scientists understand ancient human population migrations as well as how different human groups are biologically related to one another. For medicine, study of human genetic variation may be important because some disease-causing alleles occur more often in people from specific geographic regions. New findings show that each human has on average 60 new mutations compared to their parents.[3][4] Apart from mutations, many genes that may have aided humans in ancient times plague humans today. For example, it is suspected that genes that allow humans to more efficiently process food are those that make people susceptible to obesity and diabetes today.
No two humans are genetically identical. Even monozygotic twins, who develop from one zygote, have infrequent genetic differences due to mutations occurring during development and gene copy number variation.[2] Differences between individuals, even closely related individuals, are the key to techniques such as genetic fingerprinting. Alleles occur at different frequencies in different human populations, with populations that are more geographically and ancestrally remote tending to differ more.
Causes of differences between individuals include the exchange of genes during meiosis and various mutational events. There are at least two reasons why genetic variation exists between populations. Natural selection may confer an adaptive advantage to individuals in a specific environment if an allele provides a competitive advantage. Alleles under selection are likely to occur only in those geographic regions where they confer an advantage. The second main cause of genetic variation is due to the high degree of neutrality of most mutations. Most mutations do not appear to have any selective effect one way or the other on the organism. The main cause is genetic drift, this is the effect of random changes in the gene pool. In humans, founder effect and past small population size (increasing the likelihood of genetic drift) may have had an important influence in neutral differences between populations. The theory that humans recently migrated out of Africa supports this.
The study of human genetic variation has both evolutionary significance and medical applications. It can help scientists understand ancient human population migrations as well as how different human groups are biologically related to one another. For medicine, study of human genetic variation may be important because some disease-causing alleles occur more often in people from specific geographic regions. New findings show that each human has on average 60 new mutations compared to their parents.[3][4] Apart from mutations, many genes that may have aided humans in ancient times plague humans today. For example, it is suspected that genes that allow humans to more efficiently process food are those that make people susceptible to obesity and diabetes today.
What's the difference between genes and DNA?
Genes are actually a subset of a cell's DNA. While all of your genes
are made of DNA, your entire DNA is not composed of genes. In fact, less
than two percent of a person's DNA represents active genes! The rest of
the DNA seems to be involved mediating how the genes are expressed.
DNA, deoxyribonucleic acid, is found as long chains, with each "link" called a nucleotide. The structure of DNA is the well known double helix. Each bacterial cell generally contains a single chain of duplex DNA, called a chromosome, with about five million links in it. By comparison, cells in human beings contain 2 copies of 23 different chromosomes with around 100 million nucleotides each.
Genes were classically defined as the fundamental units of inheritance. Today we understand genes to be portions of DNA that contain the information needed by cells to live. In particular, genes are special sequences of nucleotides that are used to design proteins which carry out the work of building, maintaining, and reproducing the cell.
One can think of a genome, the sum total of all an organism's DNA sequence, as a book written in a special code. In this analogy, nucleotides are the dots and dashes of the code. Some pages of the book have instructions on how to make different proteins, these would be the genes. The other pages may have messages telling the cell where to begin making new DNA (origins of replication), how to read and edit other messages (promoters, terminators, and splicing signals), where to leave bookmarks for ready reference (binding sites), or where to bind the book (centrometric and telomeric regions)
DNA, deoxyribonucleic acid, is found as long chains, with each "link" called a nucleotide. The structure of DNA is the well known double helix. Each bacterial cell generally contains a single chain of duplex DNA, called a chromosome, with about five million links in it. By comparison, cells in human beings contain 2 copies of 23 different chromosomes with around 100 million nucleotides each.
Genes were classically defined as the fundamental units of inheritance. Today we understand genes to be portions of DNA that contain the information needed by cells to live. In particular, genes are special sequences of nucleotides that are used to design proteins which carry out the work of building, maintaining, and reproducing the cell.
One can think of a genome, the sum total of all an organism's DNA sequence, as a book written in a special code. In this analogy, nucleotides are the dots and dashes of the code. Some pages of the book have instructions on how to make different proteins, these would be the genes. The other pages may have messages telling the cell where to begin making new DNA (origins of replication), how to read and edit other messages (promoters, terminators, and splicing signals), where to leave bookmarks for ready reference (binding sites), or where to bind the book (centrometric and telomeric regions)
Genes, DNA, and chromosomes: What's the difference?
THERE are plenty of diseases that I've been told are
inherited, something to do with our genes and chromosomes. But I don't
really know the difference between DNA, genes, and chromosomes. What is
DNA?
DNA is short for deoxyribonucleic acid. It's the hereditary material in all of us and most other living organisms (excluding viruses). Plants have them too, as do bacteria.
In your
body, every cell has the same DNA. Most of it is located in your cell's
nucleus, which is the command centre of your cell. A small amount is
also found in your mitochondria, which are the energy supply powerhouses
of your cell.
All the information in our DNA is made out of four bases, which are
protein. These are adenine (A), guanine (G), cytosine (C) and thymine
(T). The order in which these bases are structured - like a very long
sentence of words - determine how you are built, like whether or not you
are a fish, and what kind of fish.
In humans, 99% of our DNA are the same. That's why we all have a face, two arms, two legs, and all the organs in the right places. The 1% that differs makes us different - and that's why some of us have blue eyes, curly hair, or even certain diseases.
I've heard our DNA is coiled in a double helix. What is that?
The DNA bases pair up with one another like a jigsaw puzzle. A partners up with T because they are physically made to fit together, while C pairs with G.
These bases are attached to a sugar and phosphate molecule called a nucleotide. Paired nucleotides are coiled in two long strands that form a spiral. This is the double (because there two) helix.
Think of it as a curvy ladder.
When your cell needs to divide, this curvy ladder opens up to make an exact copy from the floating bases in your nucleus.
OK, then what is a chromosome?
So, we now understand what goes into our DNA. Now, in the nucleus of our cells, our DNA is packaged into thread-like structures called chromosomes. Think of our DNA as long coiled double helix ladders, which now have to be even more tightly coiled, like a looped skein of thread that is sold in haberdashery shops.
The structure of the chromosome is maintained by proteins called histones.
A chromosome actually looks like a fat sausage that is constricted in the belly. The constriction (or belt) is called the centromere. One arm of the chromosome is longer than the other.
Like DNA, chromosomes are paired with each other. All of us have two sets of chromosomes because one is inherited from our mother, and the other, our father. Each set in every cell contains 23 pairs of chromosomes, which equals 46 chromosomes altogether.
22 out of these 23 chromosome pairs are autosomes. The final pair are sex chromosomes. If you are female, you have XX sex chromosomes. Males have XY sex chromosomes.
What then is a gene?
The chromosome is the biggest unit we have talked about so far. Now the gene is even smaller than the DNA.
In our tightly coiled DNA double helix, there are subunits called genes. If the DNA is one very long sentence, then the genes are the "words" or "phrases" of the sentence.
Each of our genes contain a set of chemical bases, which are the instructions to code a certain protein, which in turn gives rise to a particular trait that we may have.
When our genes want to code for a certain protein, that part of the DNA opens up. The exposed A,T,C,G then attracts complementary bases from the soup swimming in the nucleus. This is called the messenger RNA (ribonucleic acid).
This messenger RNA (mRNA) swims out of the nucleus to our cell's cytoplasm. The mRNA goes to our cells' factory, called the ribosome. The ribosome reads the mRNA and starts assembling the proteins to make whatever is needed. This protein chain goes on and on until the ribosome encounters a STOP sign in the mRNA, called a codon, which is basically an empty sequence.
All this is going on in our bodies even as I type this, and you read this. On and on, with mistakes rarely made. It's the very basis of life itself.
So basically, if a disorder is 'inherited' or 'runs in the family', it's all the genes?
Sometimes. Some disorders like haemophilia or colour blindness which affects multiple members of your family are indeed passed down through gene mutations. Others are not so easy to determine. More often than not, it's a combination of genetics and environmental factors.
This explains why some people, whose genes are primed to get cancer, get cancer, and others don't, and why some people who smoke get cancer, and other smokers never do.
DNA is short for deoxyribonucleic acid. It's the hereditary material in all of us and most other living organisms (excluding viruses). Plants have them too, as do bacteria.
|
In humans, 99% of our DNA are the same. That's why we all have a face, two arms, two legs, and all the organs in the right places. The 1% that differs makes us different - and that's why some of us have blue eyes, curly hair, or even certain diseases.
I've heard our DNA is coiled in a double helix. What is that?
The DNA bases pair up with one another like a jigsaw puzzle. A partners up with T because they are physically made to fit together, while C pairs with G.
These bases are attached to a sugar and phosphate molecule called a nucleotide. Paired nucleotides are coiled in two long strands that form a spiral. This is the double (because there two) helix.
Think of it as a curvy ladder.
When your cell needs to divide, this curvy ladder opens up to make an exact copy from the floating bases in your nucleus.
OK, then what is a chromosome?
So, we now understand what goes into our DNA. Now, in the nucleus of our cells, our DNA is packaged into thread-like structures called chromosomes. Think of our DNA as long coiled double helix ladders, which now have to be even more tightly coiled, like a looped skein of thread that is sold in haberdashery shops.
The structure of the chromosome is maintained by proteins called histones.
A chromosome actually looks like a fat sausage that is constricted in the belly. The constriction (or belt) is called the centromere. One arm of the chromosome is longer than the other.
Like DNA, chromosomes are paired with each other. All of us have two sets of chromosomes because one is inherited from our mother, and the other, our father. Each set in every cell contains 23 pairs of chromosomes, which equals 46 chromosomes altogether.
22 out of these 23 chromosome pairs are autosomes. The final pair are sex chromosomes. If you are female, you have XX sex chromosomes. Males have XY sex chromosomes.
What then is a gene?
The chromosome is the biggest unit we have talked about so far. Now the gene is even smaller than the DNA.
In our tightly coiled DNA double helix, there are subunits called genes. If the DNA is one very long sentence, then the genes are the "words" or "phrases" of the sentence.
Each of our genes contain a set of chemical bases, which are the instructions to code a certain protein, which in turn gives rise to a particular trait that we may have.
When our genes want to code for a certain protein, that part of the DNA opens up. The exposed A,T,C,G then attracts complementary bases from the soup swimming in the nucleus. This is called the messenger RNA (ribonucleic acid).
This messenger RNA (mRNA) swims out of the nucleus to our cell's cytoplasm. The mRNA goes to our cells' factory, called the ribosome. The ribosome reads the mRNA and starts assembling the proteins to make whatever is needed. This protein chain goes on and on until the ribosome encounters a STOP sign in the mRNA, called a codon, which is basically an empty sequence.
All this is going on in our bodies even as I type this, and you read this. On and on, with mistakes rarely made. It's the very basis of life itself.
So basically, if a disorder is 'inherited' or 'runs in the family', it's all the genes?
Sometimes. Some disorders like haemophilia or colour blindness which affects multiple members of your family are indeed passed down through gene mutations. Others are not so easy to determine. More often than not, it's a combination of genetics and environmental factors.
This explains why some people, whose genes are primed to get cancer, get cancer, and others don't, and why some people who smoke get cancer, and other smokers never do.
DNA vs RNA
The main difference between DNA and RNA is the sugar present in the molecules. While the sugar present in an RNA molecule is ribose, the sugar present in a molecule of DNA is deoxyribose. Deoxyribose is the same as ribose, except that the former has one more OH.
DNA does not usually exist as a single molecule, but instead as a tightly-associated pair of molecules. These two long strands entwine like vines, in the shape of a double helix. This arrangement of DNA strands is called antiparallel. The asymmetric ends of DNA strands are referred to as the 5′ (five prime) and 3′ (three prime) ends. One of the major differences between DNA and RNA is the sugar, with 2-deoxyribose being replaced by the alternative pentose sugar ribose in RNA. The four bases found in DNA are adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T). A fifth pyrimidine base, called uracil (U), usually takes the place of thymine in RNA and differs from thymine by lacking a methyl group on its ring.
DNA does not usually exist as a single molecule, but instead as a tightly-associated pair of molecules. These two long strands entwine like vines, in the shape of a double helix. This arrangement of DNA strands is called antiparallel. The asymmetric ends of DNA strands are referred to as the 5′ (five prime) and 3′ (three prime) ends. One of the major differences between DNA and RNA is the sugar, with 2-deoxyribose being replaced by the alternative pentose sugar ribose in RNA. The four bases found in DNA are adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T). A fifth pyrimidine base, called uracil (U), usually takes the place of thymine in RNA and differs from thymine by lacking a methyl group on its ring.
Comparison chart
| DNA | RNA | |
|---|---|---|
| Stands for: | DeoxyriboNucleicAcid | RiboNucleicAcid |
| Definition: | A nucleic acid that contains the genetic instructions used in the development and functioning of all modern living organisms(scientists believe that RNA may have been the main genetic material in primitive life forms). | A single-stranded chain of alternating phosphate and ribose units with the bases Adenine, Guanine, Cytosine, and Uracil bonded to the ribose. RNA molecules are involved in protein synthesis and sometimes in the transmission of genetic information. |
| Job/Role: | Medium of long-term storage and transmission of genetic information | Transfer the genetic code needed for the creation of proteins from the nucleus to the ribosome. |
| Unique Features: | The helix geometry of DNA is of B-Form. DNA is completely protected by the body, i.e., the body destroys enzymes that cleave DNA. DNA can be damaged by exposure to Ultra-violet rays | The helix geometry of RNA is of A-Form. RNA strands are continually made, broken down and reused. RNA is more resistant to damage by Ultra-violet rays. |
| Predominant Structure: | Double- stranded molecule with a long chain of nucleotides | A single-stranded molecule in most of its biological roles and has a shorter chain of nucleotides |
| Bases & Sugars: | Deoxyribose sugar; phosphate backbone; Four bases: adenine, guanine, cytosine and thymine | Ribose sugar; phosphate backbone. Four bases: adenine, guanine, cytosine, and uracil |
| Pairing of Bases: | A-T(Adenine-Thymine), G-C(Guanine-Cytosine) | A-U(Adenine-Uracil), G-C(Guanine-Cytosine) |
| Stability: | Deoxyribose sugar in DNA is less reactive because of C-H bonds. Stable in alkaline conditions. DNA has smaller grooves, which makes it harder for enzymes to "attack" DNA. | Ribose sugar is more reactive because of C-OH (hydroxyl) bonds. Not stable in alkaline conditions. RNA has larger grooves, which makes it easier to be attacked by enzymes. |
| Propagation: | DNA is self-replicating. | RNA is synthesized from DNA when needed. |
Sunday, April 28, 2013
Humans, Chimpanzees and Monkeys Share DNA but Not Gene Regulatory Mechanisms
DNA factors that contribute to the differences were described on Nov. 6 at the American Society of Human Genetics 2012 meeting in a presentation by Yoav Gilad, Ph.D., associate professor of human genetics at the University of Chicago.
Dr. Gilad reported that up to 40% of the differences in the expression or activity patterns of genes between humans, chimpanzees and rhesus monkeys can be explained by regulatory mechanisms that determine whether and how a gene's recipe for a protein is transcribed to the RNA molecule that carries the recipe instructions to the sites in cells where proteins are manufactured.
In addition to improving scientific understanding of the uniqueness of humans, studies such as the investigation conducted by Dr. Gilad and colleagues could have relevance to human health and disease.
"Through inter-species' comparisons at the DNA sequence and expression levels, we hope to identify the genetic basis of human specific traits and in particular the genetic variations underlying the higher susceptibility to certain diseases such as malaria and cancer in humans than in non-human primates," said Dr. Gilad.
Dr. Gilad and his colleagues studied gene expression in lymphoblastoid cell lines, laboratory cultures of immortalized white blood cells, from eight humans, eight chimpanzees and eight rhesus monkeys.
They found that the distinct gene expression patterns of the three species can be explained by corresponding changes in genetic and epigenetic regulatory mechanisms that determine when and how a gene's DNA code is transcribed to a messenger RNA (mRNA) molecule.
Dr. Gilad also determined that the epigenetics process known as histone modification also differs in the three species. The presence of histone marks during gene transcription indicates that the process is being prevented or modified.
"These data allowed us to identify both conserved and species-specific enhancer and repressor regulatory elements, as well as characterize similarities and differences across species in transcription factor binding to these regulatory elements," Dr. Gilad said.
Among the similarities among the three species were the promoter regions of DNA that initiated transcription of a particular gene.
In all three species, Dr. Gilad's lab found that transcription factor binding and histone modifications were identical in over 67% of regulatory elements in DNA segments that are regarded as promoter regions.
The researchers presentation is titled, "Genome-wide comparison of genetic and epigenetic regulatory mechanisms in primates."
New Form Of Humans Being Made? DNA, Cellular Upgrades?
Genetic Data and Fossil Evidence Tell Differing Tales of Human Origins
After decades of digging, paleoanthropologists looking for fossilized human bones have established a reasonably clear picture: Modern humans arose in Africa some 200,000 years ago and all archaic species of humans then disappeared, surviving only outside Africa, as did the Neanderthals in Europe. Geneticists studying DNA now say that, to the contrary, a previously unknown archaic species of human, a cousin of the Neanderthals, may have lingered in Africa until perhaps 25,000 years ago, coexisting with the modern humans and on occasion interbreeding with them.
reported on Thursday in the journal Cell, after decoding the entire genome of three isolated hunter-gatherer peoples in Africa, hoping to cast light on the origins of modern human evolution. But the finding is regarded skeptically by some paleoanthropologists because of the absence in the fossil record of anything that would support the geneticists’ statistical calculations.
Two of the hunter-gatherers in the study, the Hadza and Sandawe of Tanzania, speak click languages and carry ancient DNA lineages that trace to the earliest branchings of the human family tree. The third group is that of the forest-dwelling pygmies of Cameroon, who also have ancient lineages and unusual blood types.
The geneticists, led by Joseph Lachance and Sarah A. Tishkoff of the University of Pennsylvania, decoded the entire genomes of five men from each of these groups. The costs of whole-genome sequencing have fallen so much that the technique can now be applied to populations for the first time, said Dr. Tishkoff, who paid the company Complete Genomics around $10,000 for each of the 15 genomes.
Among the DNA sequences special to pygmies, Dr. Tishkoff and colleagues found a variant of the usual gene that controls development of the pituitary gland, the source of the hormones that control reproduction and growth. This could be the cause of the pygmies’ short stature and early age of reproduction, the researchers say.
The genomes of the pygmies and the Hadza and Sandawe click-speakers contained many short stretches of DNA with highly unusual sequences. Through mutation, the genomes of species that once had a common ancestor grow increasingly unlike one another. Dr. Tishkoff’s team interprets these divergent DNA sequences as genetic remnants of an interbreeding with an archaic species of human. Genetic calculations suggest the interbreeding took place between 20,000 and 80,000 years ago.
From calculations of the amount of divergence in the DNA, the geneticists estimate that the archaic species split from the ancestors of modern humans about 1.2 million years ago, about the same time as did the ancestors of the Neanderthals, who dominated Europe during the end of the last ice age.
But the archaic species has a different DNA sequence from that of Neanderthals, whose genome has been reconstructed from DNA surviving in ancient bones, and so may be a sister species, the geneticists say.
Inquiries into human origins are on strong ground when genetic data and fossil evidence point in the same direction, but at present geneticists and paleoanthropologists have somewhat different stories to tell. All human fossil remains in Africa for the last 100,000 years, and probably the last 200,000 years, are of modern humans, providing no support for a coexistent archaic species. Another team of geneticists reported in 2010 the finding that Neanderthals had interbred 100,000 years ago with Europeans and Asians, but not Africans. This, too, conflicted with the fossil evidence in implying that modern humans left Africa 100,000 years ago, some 55,000 years before the earliest known fossil evidence of this exodus.
In a report still under review, a third group of geneticists says there are signs of Neanderthals having interbred with Asians and East Africans. But Neanderthals were a cold-adapted species that never reached East Africa.
These three claims of interbreeding have opened up a serious discordance between geneticists and paleoanthropologists. For digesting the geneticists’ claims, “sup with a long spoon,” advised Bernard Wood, a paleoanthropologist at George Washington University.
Richard Klein, a paleoanthropologist at Stanford University, said the new claim of archaic and modern human interbreeding “is a further example of the tendency for geneticists to ignore fossil and archaeological evidence, perhaps because they think it can always be molded to fit the genetics after the fact.”
Dr. Klein said the claims of interbreeding could be “a methodological artifact” in the statistical assumptions on which the geneticists’ calculations are based. The flaw may come to light when enough inconsistent claims are published. “Meanwhile, I think it’s important to regard such claims skeptically when they are so clearly at odds with the fossil and archaeological records,” he said.
Dr. Tishkoff said that she agreed on the need for caution in making statistical inferences, and that there are other events besides interbreeding, like a piece of DNA getting flipped around the wrong way, that can make a single DNA sequence look ancient. “But when you see it at a genomewide level, it’s harder to explain away,” she said.
A co-author, Joshua M. Akey of the University of Washington in Seattle, said he was “reasonably confident that what we are seeing in Africa does represent archaic introgression.” The archaic sequences make up only 2.5 percent of the genomes of the living hunter-gatherers, and there is no evidence that they are being favored by natural selection. They may, therefore, have no effect on a person’s physical form, which could explain why the fossils show little sign of them, Dr. Akey said.
Although all known African fossils are of modern humans, a 13,000-year-old skull from the Iwo Eleru site in Nigeria has certain primitive features. “This might have indicated interbreeding with archaics,” saidChris Stringer, a paleoanthropologist at the Natural History Museum in London. “For half of Africa we really have no fossil record to speak of, so I think it’s quite likely there were surviving archaic forms living alongside modern humans.”
Paleoanthropologists like Dr. Klein consider it “irresponsible” of the geneticists to publish genetic findings about human origins without even trying to show how they may fit in with the existing fossil and archaeological evidence. Dr. Akey said he agreed that genetics can provide only part of the story. “But hopefully this is just a period when new discoveries are being made and there hasn’t been enough incubation time to synthesize all the disparities,” he said.
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