General Science Info: 2011

DNA

Deoxyribo nucleic acid or DNA is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms (with the exception of RNA viruses). The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints, like a recipe or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information. Along with RNA and proteins, DNA is one of the three major macromolecules that are essential for all known forms of life.

DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds. These two strands run in opposite directions to each other and are therefore anti-parallel. Attached to each sugar is one of four types of molecules called nucleobases (informally, bases). It is the sequence of these four nucleobases along the backbone that encodes information. This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA, in a process called transcription.

Within cells, DNA is organized into long structures called chromosomes. These chromosomes are duplicated before cells divide, in a process called DNA replication. Eukaryotic organisms (animals, plants, fungi, and protists) store most of their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts. In contrast, prokaryotes (bacteria and archaea) store their DNA only in the cytoplasm. Within the chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.

What is Mutation

Mutations are changes in a genomic sequence : The DNA sequence of a cell's genome or the DNA or RNA sequence of a virus.

Mutations are caused by radiation, viruses, transposons and mutagenic chemicals, as well as errors that occur during meiosis or DNA replication. They can also be induced by the organism itself, by cellular processes such as hyper mutation.

Mutation can result in several different types of change in sequences (DNA) these can either have no effect, alter the product of a gene, or prevent the gene from functioning properly or completely. Studies in the fly Drosophila melanogaster suggest that if a mutation changes a protein produced by a gene, this will probably be harmful, with about 70 percent of these mutations having damaging effects, and the remainder being either neutral or weakly..

Viruses that use RNA as their genetic material have rapid mutation rates, which can be an advantage since these viruses will evolve constantly and rapidly, and thus evade the defensive responses of e.g. the human immune system.

Carcinoma

A carcinoma is any malignant cancer that arises from epithelial cells. Carcinomas invade surrounding tissues and organs and may metastasize, or spread, to lymph nodes and other sites.

”Carcinoma in situ” (CIS) is a pre-malignant condition, in which some cytological signs of malignancy are present, but there is no histological evidence of invasion through the epithelial basement membrane.

Carcinoma, like all neoplasia, is classified by its histopathological appearance. Adenocarcinoma and squamous cell carcinoma, two common descriptive terms for tumors, reflect the fact that these cells may have glandular or squamous cell appearances respectively. Severely anaplastic tumors might be so undifferentiated that they do not have a distinct histological appearance (undifferentiated carcinoma).

Sometimes a tumor is referred to by the presumptive organ of the primary (eg carcinoma of the prostate) or the putative cell of origin (hepatocellular carcinoma, renal cell carcinoma).

Metastatic carcinoma can be diagnosed through biopsy, including fine-needle aspiration, core biopsy, or subtotal removal of single node.

Thymine

Thymine is one of the four nucleobases in the nucleic acid of DNA that are represented by the letters G–C–A–T. The others are adenine, guanine, and cytosine. Thymine (T) almost always pairs with adenine, although thymine dimers also occur due to UV light exposure.

This mutation is responsible for melanoma formation. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. As the name suggests, thymine may be derived by methylation of uracil at the 5th carbon.

In RNA, thymine is replaced with uracil in most cases. In DNA, thymine (T) binds to adenine (A) via two hydrogen bonds to assist in stabilizing the nucleic acid structures.

Thymine combined with deoxyribose creates the nucleoside deoxythymidine, which is synonymous with the term thymidine. Thymidine can be phosphorylated with one, two, or three phosphoric acid groups, creating, respectively, TMP, TDP, or TTP (thymidine mono-, di-, or triphosphate).

One of the common mutations of DNA involves two adjacent thymines or cytosine, which, in presence of ultraviolet light, may form thymine dimers, causing “kinks” in the DNA molecule that inhibit normal function.

Thymine could also be a target for actions of 5-fluorouracil (5-FU) in cancer treatment. 5-FU can be a metabolic analog of thymine (in DNA synthesis) or uracil (in RNA synthesis). Substitution of this analog inhibits DNA synthesis in actively-dividing cells.

Thymine bases are frequently oxidized to hydantoins over time after the death of an organism.

Worms

Worms are invertebrate species that are not footed. There are worms that live in the land and water while others are parasites that live inside the animal’s body.

There are over 55,000 species of worms. Four main groups are tapeworms, flatworms, gilik worms and roundworms.

Worms are simple structures such as flatworms, microscopic organisms which belong to very small size. However, several parasitic tapeworms that can grow to more than 20 meters. Parasitic worms in the body of animals and plants, some are even inside the human body. Mematoda worm larvae can enter the human kemulut accidentally and penetrated into the lungs. Man will be coughing and swallowing the larvae, so that the larvae enter the stomach. In the stomach they eat foods that are eaten by humans. Adult worms lay eggs and the eggs can be discarded with the feces. The eggs of this parasite can infect other people.

WORMS LAND

Earthworms belong roundworms or annelids. Soil earthworms swallow and digest the plant material contained therein. Earthworm body consists of a row of rings. The body is covered with fine hairs that serve to help move the body. Including animal hermaphrodite earthworms.

SEA WORMS

The structure of marine worms or Polychaeta Annelid not much different, except for fine hairs on the surface of its body is longer. Marine worms eat the plants but also many who hunt marine worms poked by long vessels (proboscis) to catch prey.

Gene Therapy

Gene therapy is a technique that introduces an altered gene into a person’s body to carry out the work of a mulfunctioning gene. The procedure aims to treat or cure diseases that have been caused by faulty genes.

There are more than 4000 genetic disorders, and that number is likely to increase as we discover more about our DNA. Many of these diseases are incurable.

Gene therapy is attempts to cure genetic disorders by replacing a defective gene in the human body with a properly functioning gene.

The first FDA-approved gene therapy procedure was performed by Dr. French Anderson in September 1994, on a child born with a rare genetic disorder, known as severe combined immunodeficiency. This caused her to have no effective immune system, resulting in frequent infections, and a poor quality of life.

The procedure consisted of removing the child’s white blood cells, inserting the good functional copies of the desired gene into some of the cells, and then putting them back into her body. The procedure is not a permanent fix, and needs to be performed every few months. But she’s alive and well and has a strengthened immune system.

Lymph System

Lymph system is a system of transport lymph fluid from tissues into the blood. The system also contains cells that make the body able to ward off disease.

When blood flow throughout the circulatory system, a liquid substance called lymph seeps through capillary walls. This liquid deliver oxygen and nutrients essential to the tissue cells. Lymph fluid dispose of substances and return the rest seeps into the bloodstream through capillary walls.

Every day about 24 liters of lymph fluid seeps through capillary walls into the tissue. Most of the back behind kealiran seeping blood. However, approximately 4liter of them still remained in the network. Lymphatic system transports waste materials are called nodes and build it through the blood vessels of the chest.

Nodes form a clear liquid that carries dissolved substances, cellular debris, and pathogens such as bacteria and viruses. Lymph flow only toward unity is out of the network. Unlike blood, pumped by the heart, lymph through the lymph system with the help of muscle-skeletal muscles, which pushes the fluid when they contract. Valves in lymph vessels to prevent fluid to flow backwards.

As lymph fluid flows through lymph vessels, he crossed the lymph node. This is where white blood cells called macrophages and swallowing cum cellular debris and pathogens. Other white blood cells called lymphocytes produce antibodies, ie chemicals that target the pathogens for destruction. Organs of the other nodes have the same role. Lymphocytes and macrophages work together to form the immune system, the body’s most powerful defenses to ward off disease.

Chromatin

Chromatin is that portion of the cell nucleus which contains all of the DNA of the nucleus in animal or plant cells. (A small amount of special DNA is also found in the mitochondria of the cell cytoplasm outside of the cell nucleus.)

DNA is never found as a naked molecule in animal or plant cell nuclei. DNA is always found in association with histone proteins (soluble in acid solutions), HMG proteins (soluble in neutral saline), residual proteins (soluble in concentrated urea solutions), phosphoproteins (soluble in basic solutions), RNA species (soluble in aqueous phenol solutions), and lipid species (soluble in chloroform-methanol solutions). By choosing the appropriate solution, it is possible to extract each of these classes of macromolecules away from the DNA and away from the other chromatin constituents.
Smaller molecules such as steroid and thyroid hormones and vitamins A and D are also found within the cell nucleus bound to DNA or to one of the other chromatin macromolecules. These small molecules are transported to the nucleus, where they play stimulatory roles for RNA and DNA synthesis on chromatin. Viral RNA species and DNA species can also play stimulatory roles on chromatin. Some RNA species are confined to the cell nucleus, where they are synthesized on chromatin and feed back on other segments of chromatin to influence RNA or DNA synthesis.

Foreign substances such as antibiotics (actinomycin D), dyes (acridine orange), enzymes (DNase I), and complex carbohydrates (phytohemagglutinin) also penetrate the cell nucleus to the chromatin, where they also may have stimulatory or inhibitory effects on RNA or DNA synthesis.

When cells divide, the chromatin is seen as distinct chromosomes, duplicating, with an equal partition of each set of chromosomes then traveling to each of the new daughter cells. When the new chromosomes reach the new cells, they begin to un-ravel into long thin extended 10 nm. (100 A.) microfibrils called euchromatin or condensed coiled masses called heterochromatin. The study of euchromatin and heterochromatin while within intact non-dividing cells, or after isolation from such cells, has revealed that RNA synthesis occurs only in euchromatin, and not in heterochromatin. Similarly, DNA synthesis is early in euchromatin and late in heterochromatin. Mechanisms for controlling RNA or DNA synthesis in chromatin can be studied by additions or deletions of macromolecules from either isolated euchromatin or isolated heterochromatin. Such studies reveal that histone proteins are largely inhibitory, while RNA and other proteins are largely stimulatory for RNA and DNA synthesis.

The Chromatin Network is dedicated to researchers and all others interested in the study of animal and plant chromatin as found in the cell nucleus. It is evident that by such study of chromatin, we will gain a deeper understanding of gene action and gene regulation, of hormone and vitamin action and regulation, of viral action and viral regulation, and of the general physiologic processes of embryogenesis, organ regeneration, the neoplastic process, and the immune process.

Flowering Plant

Flowering plant or Angiospermae is most successful plant. Angiospermae reproduce by seed that grows inside the flower ovary. Angiospermae derived from the Greek word which means seed enclosed.

Growth angiospermae embryo enclosed in a special structure called a seed inside the flower. After the fertilization process, seeds are protected by the fruit flesh. Thus, flowering plants have a greater chance to survive and produce offspring.

Flowering plants are believed to have evolved from ancient conifers (now extinct) who lived about 250juta years ago, namely the Permian period. And in its development, flowering plants affect other living organisms.

There are two groups of flowering plants. Each is distinguished by way of the formation of leaf buds from the seeds of growth. The first group is a monocot, is a single seeds. And the group keua is dicotyledonous, ie plants that have two seed pieces.

Interest contents

In general, flower consists of four organs: the head (leaf sheath), petala (corolla), stamen or stamens (the anthers and stem juice), and pistils (the stigma, pistil stalk, and ovaries).

In the middle there are flower stamen and pistil. Stamens on the inside leaf crown. Each stamen consists of anthers that produce male sex cells called pollen, and pollen stalk that attaches anthers to the stigma.

Ovulation Sign

To determine when you are likely to ovulate – you determine when your next period is due and count back 12 to 16 days. This gives you a the number of days when a woman most likely begins ovulating.

Using an ovulation calendar or ovulation predictor kits do the work for you, but learning as much as you can about your own body is also recommended.

Gathering all the clues you can will definitely benefit your ability to pin point your time of ovulation and ultimately time intercourse so conception can occur.

There will be changes in your cervical mucus.

The amount of cervical mucus increases as well as the texture.

The quantity and texture change indicates the rising levels of estrogen. When the cervical mucus resembles raw egg whites, woman is generally considered to be at her most fertile.

It is this mucus, resembling raw egg whites, which coats the path that the sperm will take on it’s journey through the uterus, into the fallopian tubes and to your eggs.

Your body temperature will rise.

After you have ovulated, your temperatures can increases, and that’s what the basal body temperature thermometer detects. When your temperature rises sharply, it means you have ovulated and your body has released the egg. This stimulates the production of the hormone progesterone, which makes your body temperature elevate.

A woman is at her most fertile those 2 to 3 days before her temperature rises, and sometimes it takes up to 2 days AFTER ovulation for the progesterone to rise enough to raise your body’s temperature.

This is why it is always recommended that you chart your temperature each morning for a few months. The better you are able to detect a pattern and pinpoint your likely ovulatory date, the better your chances are.

Lower abdominal discomfort.

There are women actually can feel when their bodies are ovulating. The feelings are said to range from mild aches to severe pain, and can last from a short minute up to a couple of hours.

Resource : www.babyhopes.com

Ovulation Spotting

Some women who are trying to get pregnant are lucky, in some ways. They have a regular cycle of exactly 28 (or maybe 25, or maybe 30) days, and so they can easily enough predict when they’re ovulating. Other women never really know when they’re going to be fertile because their cycle is irregular, and so they have to rely on other signs. Some of the most common and most reliable methods of tracking ovulation are basal body temperature and cervical mucus charting, but in some cases a woman may experience consistent ovulation spotting that can help her know when the time is right.

First, you need to understand a little something about ovulation. Ovulation is the release of a mature egg by the ovaries. The egg travels into the fallopian tube, where it can be fertilized. Ovulation takes place sometime between day 11 and day 21 of their cycle. Most women ovulate every month, but some may occasional experience anovulation (missed ovulation) from time to time, for a variety of reasons.

Sometimes a woman will experience “mittelschmerz,” which literally means “middle pain.” This is pain in the ovarian region and occurs during ovulation. If you’re a woman who typically experiences this, you might be able to help predict ovulation.

Some women will have a little bit of bleeding around this time, as well. Ovulation spotting is usually brown or pink in color. It will often be mixed along with cervical mucus. If it’s more than just a little bit of spotting, however, it’s probably not indicative of ovulation.

Ovulation spotting is most likely caused by the hormones that work with the follicle. These hormones cause the surface of the follicle to weaken, which can create a hole. This is what allows the egg to pass. In some cases, this also causes light bleeding. Other experts believe that the bleeding can be caused by a rise in estrogen that happens during ovulation.

You may not have ovulation spotting every month. It may only happen occasionally. For some women, it’s like clockwork. If yours is consistent, charting it and comparing it to basal body temperature and cervical mucus can help you get a better handle on knowing when you ovulate.

Bacteria

Bacteria are single-celled microorganisms which their structure is simpler than the cells making up the bodies of animals and plants. Bacteria can be found in every place. The bacteria breed in soil, air, even in our digestive system.

Most of the types of bacteria that are not classified as dangerous organisms. However, some species belonging to pathogenic bacteria can cause disease. According to its shape, pathogenic bacteria are divided into three groups. Coccus-shaped bacteria and can cause a hoarse throat, ulcers, and pneumonia. Elongated rod-shaped bacteria hasilus that can cause typhoid and salmonella. Spirokaeta spiral-shaped bacteria and can cause Lyme disease and syphilis.

Bacteria infiltrate into the body through various ways, namely through the sprinkling of water is inhaled from the air, the skin wound, water or food that is swallowed, and reproductive systems. When bacteria enter the body successfully, the bacteria eat, splitting, and release toxic substances that can harm human cells. Usually the immune system can recognize bacteria and destroy it immediately. Infection also can be treated with antibiotics. Bacterial infections can be prevented by immunization, personal hygiene, including clean drinking water, and clean the wound with antiseptic.

Gene Expression

In genetics gene expression is the most fundamental level at which genotype gives rise to the phenotype. The genetic code is “interpreted” by gene expression, and the properties of the expression products give rise to the organism’s phenotype.

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as rRNA genes or tRNA genes, the product is a functional RNA. The process of gene expression is used by all known life – eukaryotes (including multicellular organisms), prokaryotes (bacteria and archaea) and viruses – to generate the macromolecular machinery for life.

Several steps in the gene expression process may be modulated, including the transcription, RNA splicing, translation, and post-translational modification of a protein. Gene regulation gives the cell control over structure and function, and is the basis for cellular differentiation, morphogenesis and the versatility and adaptability of any organism. Gene regulation may also serve as a substrate for evolutionary change, since control of the timing, location, and amount of gene expression can have a profound effect on the functions (actions) of the gene in a cell or in a multicellular organism.

Causes of Dehydration

The immediate causes of dehydration include not enough water, too much water loss, or some combination of the two. Sometimes it is not possible to consume enough fluids because we are too busy, lack the facilities or strength to drink, or are in an area without potable water (while hiking or camping, for example). Additional causes of dehydration include:

- Diarrhea - the most common cause of dehydration and related deaths. The large intestine absorbs water from food matter, and diarrhea prevents this function, leading to dehydration.

- Sweating - the body's cooling mechanism releases a significant amount of water. Hot and humid weather and vigorous physical activity can further increase fluid loss from sweating.

- Frequent urination - usually caused by uncontrolled diabetes, but also can be due to alcohol and medications such as diuretics, antihistamines, blood pressure medications, and anti-psychotics.

- Diabetes - high blood sugar levels cause increased urination and fluid loss. Tips for handling summer heat for people with diabetes.

- Vomiting - leads to a loss of fluids and makes it difficult to replace water by drinking it.

- Burns - water seeps into damaged skin and the body loses fluids.

What is Chromosomes

A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. The word ”chromosome” comes from the Greek (”chroma”, color) and (”soma”, body) due to their property of being very strongly stained by particular dyes.

DNA and histone proteins are packaged into structures called chromosomes. Image Credit: U.S. National Library of Medicine
Chromosomes vary widely between different organisms. The DNA molecule may be circular or linear, and can be composed of 10,000 to 1,000,000,000 nucleotides in a long chain. Typically eukaryotic cells (cells with nuclei) have large linear chromosomes and prokaryotic cells (cells without defined nuclei) have smaller circular chromosomes, although there are many exceptions to this rule. Furthermore, cells may contain more than one type of chromosome; for example, mitochondria in most eukaryotes and chloroplasts in plants have their own small chromosomes.
In eukaryotes, nuclear chromosomes are packaged by proteins into a condensed structure called chromatin. This allows the very long DNA molecules to fit into the cell nucleus. The structure of chromosomes and chromatin varies through the cell cycle. Chromosomes are the essential unit for cellular division and must be replicated, divided, and passed successfully to their daughter cells so as to ensure the genetic diversity and survival of their progeny. Chromosomes may exist as either duplicated or unduplicated—unduplicated chromosomes are single linear strands, whereas duplicated chromosomes (copied during synthesis phase) contain two copies joined by a centromere. Compaction of the duplicated chromosomes during mitosis and meiosis results in the classic four-arm structure. Chromosomal recombination plays a vital role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe and die, or it may aberrantly evade apoptosis leading to the progression of cancer.

What is a Gene?

A gene is a unit of heredity in a living organism. It normally resides on a stretch of DNA that codes for a type of protein or for an RNA chain that has a function in the organism. All living things depend on genes, as they specify all proteins and functional RNA chains.

Genes hold the information to build and maintain an organism’s cells and pass genetic traits to offspring, although some organelles (e.g. mitochondria) are self-replicating and are not coded for by the organism’s DNA.

The notion of a gene is evolving with the science of genetics, which began when Gregor Mendel noticed that biological variations are inherited from parent organisms as specific, discrete traits.

The biological entity responsible for defining traits was later termed a ”gene”, but the biological basis for inheritance remained unknown until DNA was identified as the genetic material in the 1940s.

All organisms have many genes corresponding to many different biological traits, some of which are immediately visible, such as eye color or number of limbs, and some of which are not, such as blood type or increased risk for specific diseases, or the thousands of basic biochemical processes that comprise life.

The vast majority of living organisms encode their genes in long strands of DNA. DNA (deoxyribonucleic acid) consists of a chain made from four types of nucleotide subunits, each composed of: a five-carbon sugar (2′-deoxyribose), a phosphate group, and one of the four bases adenine, cytosine, guanine, and thymine.

What is Human Genetics?

Human genetics is defined as the study of how genetic inheritance takes place in the human species, or how inheritance of various characteristics from parents to kids takes place. The process of genetic inheritance in human beings and the study of human heredity now hold a central position in the field of science. The interest in the query “What is Human Genetics” is fueled from the fundamental need to understand how human genetics and the process of human inheritance affect the manifestation of genetic disorders.

What is Genetics

Genetics is the study of heredity, the process in which a parent passes certain genes onto their children. A person's appearance -- height, hair color, skin color, and eye color -- are determined by genes. Other characteristics affected by heredity.

alternative name of genetics is Homozygous, Inheritance, Heterozygous, Inheritance patterns, Heredity and disease, Heritable, Genetic markers.

Human beings have cells with 46 chromosomes -- 2 sex chromosomes and 22 pairs of nonsex (autosomal) chromosomes. Males are "46, XY" and females are "46, XX." The chromosomes are made up of strands of genetic information called DNA.

Genes are sections of DNA. The location of the gene is called the locus. Most genes carry information that is necessary to make a protein.

The pairs of autosomal chromosomes (one from the mother and one from the father) carry basically the same information. That is, each has the same genes. However, there may be slight variations of these genes. These slight differences occur in less than 1% of the DNA sequence and produce variants of a particular gene called alleles.

If a gene is abnormal, it may lead to an abnormal protein or an abnormal amount of a normal protein. Since the autosomal chromosomes are paired, there are two copies of each gene, one from each parent. If one of these genes is defective, the other may make enough protein so that no disease is seen. This is called a recessive disease, and the gene is said to be inherited in a recessive pattern.

However, if only one abnormal gene is needed to produce a disease, it's called a dominant hereditary disorder. In the case of a dominant disorder, if one abnormal gene is inherited from mom or dad, the child will likely show the disease.

A person with one abnormal gene is termed heterozygous for that gene. If a child receives an abnormal recessive disease gene from both parents, the child will show the disease and will be homozygous for that gene.

If two parents each have one copy of a recessive disease gene, then each child has a 25% (1 in 4) chance of showing the disease. If one parent has two copies of the disease gene and the other has one copy, then each child has a 50% (1 in 2) chance of being homozygous.

Resource : www.righthealth.com

Genetics Definition

Genetics is the study of heredity, the process in which a parent passes certain genes onto their children. A person's appearance -- height, hair color, skin color, and eye color -- are determined by genes. Other characteristics affected by heredity:

- Likelihood of getting certain diseases
- Mental abilities
- Natural talents

An abnormal trait (anomaly) passed down through families (inherited) may:

- Have no effect on your health or well being -- for example, it may just involve a white patch of hair or an extended earlobe
- Be of minor consequence -- for example, color blindness
- Have a dramatic effect on your quality or length of life

For most genetic disorders, genetic counseling is advised. Many people may also want to seek prenatal diagnosis.

The terms anomaly, abnormality, disorder, defect, disease, and syndrome are not used consistently, and do not have precise definitions.

What is RNA?

RNA is transcribed from DNA by enzymes called RNA polymerases and is generally further processed by other enzymes. RNA is central to protein synthesis. Here, a type of RNA called messenger RNA carries information from DNA to structures called ribosomes. These ribosomes are made from proteins and ribosomal RNAs, which come together to form a molecular machine that can read messenger RNAs and translate the information they carry into proteins. There are many RNAs with other roles – in particular regulating which genes are expressed, but also as the genomes of most viruses.

RNA and DNA are both nucleic acids, but differ in three main ways. First, unlike DNA which is double-stranded, RNA is a single-stranded molecule in most of its biological roles and has a much shorter chain of nucleotides. Second, while DNA contains ”deoxyribose”, RNA contains ”ribose” (there is no hydroxyl group attached to the pentose ring in the 2′ position in DNA). These hydroxyl groups make RNA less stable than DNA because it is more prone to hydrolysis. Third, the complementary base to adenine is not thymine, as it is in DNA, but rather uracil, which is an unmethylated form of thymine. For instance, determination of the structure of the ribosome—an enzyme that catalyzes peptide bond formation—revealed that its active site is composed entirely of RNA.

General Science Info

DNA