Category Archives: DNA

DNA, or deoxyribonucleic acid, is like a blueprint of biological guidelines that a living organism must follow to exist and remain functional. RNA, or ribonucleic acid, helps carry out this blueprint's guidelines. Of the two, RNA is more versatile than DNA, capable of performing numerous, diverse tasks in an organism, but DNA is more stable and holds more complex information for longer periods of time.

DNA and RNA are nucleic acids. Nucleic acids are long biological macromolecules that consist of smaller molecules called nucleotides. In DNA and RNA, these nucleotides contain four nucleobases sometimes called nitrogenous bases or simply bases two purine and pyrimidine bases each.

DNA is found in the nucleus of a cell (nuclear DNA) and in mitochondria (mitochondrial DNA). It has two nucleotide strands which consist of its phosphate group, five-carbon sugar (the stable 2-deoxyribose), and four nitrogen-containing nucleobases: adenine, thymine, cytosine, and guanine.

During transcription, RNA, a single-stranded, linear molecule, is formed. It is complementary to DNA, helping to carry out the tasks that DNA lists for it to do. Like DNA, RNA is composed of its phosphate group, five-carbon sugar (the less stable ribose), and four nitrogen-containing nucleobases: adenine, uracil (not thymine), guanine, and cytosine.

In both molecules, the nucleobases are attached to their sugar-phosphate backbone. Each nucleobase on a nucleotide strand of DNA attaches to its partner nucleobase on a second strand: adenine links to thymine, and cytosine links to guanine. This linking causes DNA's two strands to twist and wind around each other, forming a variety of shapes, such as the famous double helix (DNA's "relaxed" form), circles, and supercoils.

In RNA, adenine and uracil (not thymine) link together, while cytosine still links to guanine. As a single stranded molecule, RNA folds in on itself to link up its nucleobases, though not all become partnered. These subsequent three-dimensional shapes, the most common of which is the hairpin loop, help determine what role the RNA molecule is to play as messenger RNA (mRNA), transfer RNA (tRNA), or ribosomal RNA (rRNA).

DNA provides living organisms with guidelinesgenetic information in chromosomal DNAthat help determine the nature of an organism's biology, how it will look and function, based on information passed down from former generations through reproduction. The slow, steady changes found in DNA over time, known as mutations, which can be destructive, neutral, or beneficial to an organism, are at the core of the theory of evolution.

Genes are found in small segments of long DNA strands; humans have around 19,000 genes. The detailed instructions found in genesdetermined by how nucleobases in DNA are orderedare responsible for both the big and small differences between different living organisms and even among similar living organisms. The genetic information in DNA is what makes plants look like plants, dogs look like dogs, and humans look like humans; it is also what prevents different species from producing offspring (their DNA will not match up to form new, healthy life). Genetic DNA is what causes some people to have curly, black hair and others to have straight, blond hair, and what makes identical twins look so similar. (See also Genotype vs Phenotype.)

RNA has several different functions that, though all interconnected, vary slightly depending on the type. There are three main types of RNA:

DNA's genes are expressed, or manifested, through the proteins that its nucleotides produce with the help of RNA. Traits (phenotypes) come from which proteins are made and which are switched on or off. The information found in DNA determines which traits are to be created, activated, or deactivated, while the various forms of RNA do the work.

One hypothesis suggests that RNA existed before DNA and that DNA was a mutation of RNA. The video below discusses this hypothesis in greater depth.

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DNA vs RNA - Difference and Comparison | Diffen

An Interactive Animated Nonlinear Tutorial by Eric Martz Adapted for using Jmol instead of Chime, by Angel Herrez Part of Biomodel website by Angel Herrez, Univ. de Alcal (Spain)

Disponible tambin en espaol. Tambm disponvel em portugus. Auch verfgbar auf Deutsch. Disponible aussi en franais.

This version works in any Java-compatible browser. Java Virtual Machine must be installed (JVM, included with some operating systems or available in Sun's Java website). More tutorials on DNA and proteins, in English, Spanish, etc., are indexed at molvisindex.org.

If you prefer using Chime for molecular models, the page using it is still available, with equivalent content and functionality.

This tutorial is designed to complement Biology or Biochemistry and Molecular Biology books, so it is not by itself a complete introduction to DNA structure. Please, check the original source for more recent versions. You can also read the version history.

You can request a copy of this tutorial for off-line use; once you have your own copy on your computer's hard disk, you can use it without an Internet connection (and it will run faster).

Methods, Acknowledgements, and References.

Do you know there are more tutorials at MolviZ.Org? Feedback/Requests to or .

More about Jmol: Jmol home page.

The use of this work is subjected to the conditions stated on the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License (details)

This DNA Tutorial is being used in the Biomedical Sciences Curriculum developed by Project Lead The Way, Inc., a not-for-profit corporation that provides curriculum at no charge to high schools and middle schools located in the United States.

This DNA Tutorial (English and Spanish versions) has been included in BioMolecular Explorer 3D, version 2, a website+CD-ROM designed to give high school biology teachers easy access to interactive 3D structures of biologically significant molecules.

This DNA Tutorial (English and Spanish versions) has been included in the live bootable DVD Xplora Knoppix, by Xplora - The European Science Education Gateway.

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DNA Structure - Contents page

Despite what you may have seen in some textbooks, DNA is not built like a twisted ladder. The helix, or spiral, is an inherent feature of the DNA molecule. Notice, for instance, that in the picture below, that the groove on the left side of the picture is much larger than the right side. This is because the paired bases in the center meet each other at an angle.

DNA is a very large molecule; the image here shows only a tiny fraction of the typical molecule. If an entire molecule of DNA from the virus "bacteriophage lambda" were shown at this scale, the image would be 970 meters high. For the bacterium Escherichia coli, the image would be 80 kilometers long. And for a typical piece of DNA from a eukaryote cell, the image would stretch for 1600 kilometers, about as far as it is from Dallas to Washington, D. C.! Obviously such a large molecule is not fully stretched out inside the cell, but is wound around proteins called histones which protect the DNA.

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DNA - University of California Museum of Paleontology

rotten > Library > Medicine > DNA How did life first get started on this planet? And why does it suck so much? The answer is found in DNA.

DNA was discovered in 1869, but at the time, no one really knew what it was or whether it was important. Scientists knew that it was a complicated molecule found inside the cells of living things, and they suspected it had something to do with heredity.

In 1944, quantum physicist Erwin Schrodinger (of "Schrodinger's Cat" fame) published a collection of lectures titled What is Life? Schrodinger postulated that all life was somehow designed according a pre-set script that could found among the molecules of the body.

Following on his discoveries in the study of subatomic systems, Schrodinger believed that information about the structure of a life form was physically encoded into the life form at a very small scale, and that the code was inherited by each generation from the previous. Schrodinger challenged his contemporaries in the life sciences to find that code.

In the 1950s, two young scientists named James Watson and Francis Crick discovered that the molecules of DNA were coiled up in the double helix formation. A couple of years later, an experiment using bacteria proved that DNA was the medium for transferring hereditary -- also called genetic -- information.

By the time you finish reading this next section, you might well think DNA stands for "Do Not Ask," but it's actually an abbreviation for deoxyribonucleic acid. DNA is a string-shaped molecule arranged as two strands spiraling around each other, connected through the middle by hydrogen atoms. The shape is known as a "double helix."

The DNA molecule is twined very tightly, so that a large number of atoms fit into a very small space. Each strand of DNA contains a number of smaller molecule-like clusters of atoms, known as nucleotides. There are four nucleotides, each usually represented by a letter -- A, T, C, or G.

From here out, everything you read is going to be pretty grossly oversimplified. The nucleotide letters are arranged into three-letter "words" known as codons. There are 64 codons, or 64 possible combinations of the four nucleotides. (There are also 64 hexagrams in the I-Ching, which may or may not be a coincidence.) Each codon is sort of like a command in computer coding -- an instruction on how to do something.

Each set of instructions is framed by a "start" and "stop" codon. These markers are like a set of parentheses. Inside the parentheses, there is one specific set of instructions, which is almost always (Make a protein.) When a new set of parentheses begin, a new instruction has been launched, such as (Make a different protein.)

These instructions are carried out by RNA, or ribonucleic acid. Here's how it works: A molecule called an enzyme bonds with DNA, and the resulting chemical reaction creates RNA. When you unstick the RNA from the DNA, the RNA carries an impression of the DNA, called a transcription.

The RNA then drops into a simmering stew of amino acids, which are the carbon-based raw materials of life. The amino acids interact chemically with the RNA segment to make proteins, in a type dictated by the information copied from the parenthetical DNA segment. Like the gears and springs in a pocket watch, proteins are the fundamental machines that do the work of life within a cell.

If your eyes are glazing over right about now, don't feel bad. It's insanely complicated. Here's an absurdly oversimplified (but surprisingly reasonable) way to think about it: DNA is like a long string of connected Legos, and RNA is like Play-Doh.

The Play-Doh (RNA) presses onto the string of Legos (DNA), which leaves an indentation in the Play-Doh. The Play-Doh gets tacky and falls away from the Legos. The now-stiff Play-Doh drops into a pile of loose Legos (amino acids). As they bang around together, appropriately shaped Legos snap into the impressions left in the Play-Doh to make a new Lego construct (a protein).

The type and number of proteins in a cell determine whether the cell is a bone cell, a blood cell, a brain cell, or a spleen cell. By following some specific combination of codons in a segment of DNA, RNA manufactures all the parts that go into a cell, and by following the entire recipe book (decoding the entire strand of DNA in the correct order and with the proper raw materials), you can incubate an entire person... or cat, dog, mouse, aardvark, bacterium, virus, fungus, sunflower or dragonfly.

So this bizarre little super-complicated molecule holds basic recipe book on how to build a human being in about eleventy million trillion easy steps. How did this come to be?

We know that the origins of DNA are the origins of life on this planet. Unfortunately knowing that and knowing the actual origins of DNA are two different things.

Experiments have demonstrated that the combination of base chemicals and environmental conditions on primitive Earth -- including lava, electrical storms, carbon and water -- were conducive to the formation of complex organic molecules. Some organic molecules formed on Earth; others may have been dropped here by passing comets or meteors. It's not quite clear how, but all these factors appear to have come together to form RNA first, then RNA eventually became more complex and developed into DNA.

There isn't really any one view about how this happened, but the earliest forms of life derived from these first building blocks. Well, according to most views, anyway. From these simple building blocks, more complex forms of life evolved through the process of mutation. Because the process described above are extremely complex and involve millions of small chemical changes, there are numerous opportunities for something to go wrong between the Legos and the Play-Doh.

Although DNA can repair itself to a certain extent, some errors persist and are inherited by the next generation of the life form in question. Over the course of a great deal of time, this eventually led to the development of opposable thumbs, tonsils and third nipples.

Although the stuff was unimaginable just 200 years ago, DNA is now a part of everyday life. Because each person inherits a unique genetic sequence, DNA has revolutionized criminal investigations by offering a not-quite infallible method of identifying suspects from the blood, semen, spit and hair they leave behind. DNA testing can be used to establish paternity within an inconsequential margin of error.

In medicine, DNA grows more prominent every day. Although the genetic code still contains mysteries, scientists have managed to unlock genetic markers for various diseases. Some diseases are directly caused by faulty DNA. Gene therapy -- in which healthy DNA is spliced onto damaged DNA -- is still in its early stages. Gene therapy shows promise in principle, but its track record in clinical trials to date isn't stellar.

Then there's genetic engineering. We may not fully understand how DNA works, or where it came from, or exactly precisely how all those little codons work, but in typical human form, we have already figured out how to monkey with them.

Genetic engineering is rampant in the U.S. food industry, including tomatoes, beets, wheat and corn. On the bright side, GE has made foods more resistant to spoilage, more easily processed, or more easily cooked. GE hybrids, whether plants or animals, are known as transgenic organisms.

In order to accomplish this goal, genetic engineers do some questionable things, like splicing fish genes onto strawberries to keep them from freezing, or splicing human genes into chickens to make them grow larger more rapidly. Some early experimentation has been done splicing human DNA into pigs in order to grow pigs with organs that can then be transplanted into humans. (Would eating bacon from these pigs constitute cannibalism?)

Much of this gene splicing is done by introducing an engineered virus into the host organism. By their nature, viruses tinker with the DNA of host cells, so the strategy has a certain logic behind it. On the other hand, if you think there's something inherently alarming about creating viruses and introducing them into animals in order to create bizarre new interspecies hybrids, you're not alone.

The ultimate frontier -- tampering with the DNA of human beings -- is just around the corner. Rumors of human cloning persist, but no proven clones have surfaced yet.

There are two predominant reasons to tamper with human DNA -- to improve the health of a living human, or to breed children with specific traits, presumably superior ones. Experiments in the former area have been hampered because patients have an annoying tendency to die. It turns out that inserting genetically engineered viruses into people and animals can be bad for their health. Who would have thought it?

Experiments in the latter field, sometimes known as eugenics, are equally troublesome. Although trials with animals have produced super-smart mice and sheep whose breast milk contains insulin, it's still relatively taboo to talk about manufacturing smart, beautiful children with an insatiable appetite for world domination.

In the old days, eugenics had to be accomplished through the cumbersome task of selective breeding, but modern geneticists are increasingly able to manipulate DNA directly to enhance qualities such as strength, resistance to disease and intelligence. Although Adolf Hitler gave eugenics a bad name during the 1940s, scientists are still plugging away to promote the practice.

Although current efforts are mostly limited to examining ways to diagnose and treat genetically transmitted diseases like cystic fibrosis and cancer, you know it won't be long before we're all battling for our lives against a generation of supermen whose genes for morality were accidentally excised by an overeager scientist trying to prevent warts.

Naturally, we won't be able to beat them. You can only hope that the technology to create these superbabies won't exist during our lifetimes... which would be fairly pointless since the technology pretty much exists already, held in check by only a rapidly fraying string of ethical posturing. After all, the last time you stopped at McDonald's, you ate a tomato with fish genes in it. Pretty much anything goes after that.

O brave new world!

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DNA - Rotten.com

DNA Structure and Function

Background History:

Mitosis in onion root tip DNA stands for deoxyribonucleic acid. DNA is pretty unusual in that it is about the only common molecule capable of directing its own synthesis.

The processes of mitosis and meiosis were discovered in the 1870s and 1890s. It was observed that, as cells divided, chromosomes moved around in a cell, and people began to wonder what their function was. It was determined that chromosomes were made of protein and DNA, about which people knew almost nothing. People began to suspect that chromosomes had something to do with genetics, but couldnt explain what/how. When enough evidence was accumulated to confirm that chromosomes did, indeed, have something to do with genetics, most people thought that in some way the protein in the chromosomes served as the genetic material. People knew that DNA was also in the chromosomes, but because its structure was unknown and people didnt know much about it, few people thought it was the genetic material.

Griffiths Experiment In 1928, Frederick Griffith performed an experiment using pneumonia bacteria and mice. This was one of the first experiments that hinted that DNA was the genetic code material. Click on the mouse button to study his experiment. He used two strains of Streptococcus pneumoniae: a smooth strain which has a polysaccharide coating around it that makes it look smooth when viewed with a microscope, and a rough strain which doesnt have the coating, thus looks rough under the microscope. When he injected live S strain into mice, the mice contracted pneumonia and died. When he injected live R strain, a strain which typically does not cause illness, into mice, as predicted they did not get sick, but lived. Thinking that perhaps the polysaccharide coating on the bacteria somehow caused the illness and knowing that polysaccharides are not affected by heat, Griffith then used heat to kill some of the S strain bacteria and injected those dead bacteria into mice. This failed to infect/kill the mice, indicating that the polysaccharide coating was not what caused the disease, but rather, something within the living cell. Since Griffith had used heat to kill the bacteria and heat denatures protein, he next hypothesized that perhaps some protein within the living cells, that was denatured by the heat, caused the disease. He then injected another group of mice with a mixture of heat-killed S and live R, and the mice died! When he did a necropsy on the dead mice, he isolated live S strain bacteria from the corpses. Griffith concluded that the live R strain bacteria must have absorbed genetic material from the dead S strain bacteria, and since heat denatures protein, the protein in the bacterial chromosomes was not the genetic material. This evidence pointed to DNA as being the genetic material. Transformation is the process whereby one strain of a bacterium absorbs genetic material from another strain of bacteria and turns into the type of bacterium whose genetic material it absorbed. Because DNA was so poorly understood, scientists remained skeptical up through the 1940s.

Hershey & Chases Experiment In 1952, Alfred Hershey and Martha Chase did an experiment which is so significant, it has been nicknamed the Hershey-Chase Experiment. Click on the virus button to study their experiment. At that time, people knew that viruses were composed of DNA (or RNA) inside a protein coat/shell called a capsid. It was also known that viruses replicate by taking over the host cells metabolic functions to make more virus. We are used to thinking and talking about viruses which invade our bodies and make us sick, but there are other, different kinds of viruses that infect other kinds of animals, still other viruses which infect plants, and even some viruses that infect bacteria. A virus which infects a bacterium is called a bacteriophage because the host bacterium cell is killed as the new virus particles leave the bacterial cell. In order to do all this, the virus must inject whatever is the viral genetic code into the host cell. Thus, people realized that the viral genetic code material had to be either its DNA or its protein capsid. Hershey and Chase sought an answer to the question, Is it the viral DNA or viral protein coat (capsid) that is the viral genetic code material which gets injected into a host bacterium cell? To try to answer this question, Hershey and Chase performed an experiment using a bacterium named Escherichia coli, or E.coli for short (named after a scientist whose last name was Escher) and a virus called T2 that is a bacteriophage that infects E.coli. Isolated T2, like other viruses, is just a crystal of DNA and protein, so it must live inside E.coli in order to make more virus like itself. When the new T2 viruses are ready to leave the host E.coli cell (and go infect others), they burst the E.coli cell open, killing it (hence the name bacteriophage). The results that Hershey and Chase obtained indicated that the viral DNA, not the protein, is its genetic code material.

Hershey and Chase used radioactive chemicals to distinguish between (label) the protein capsid and the DNA in T2 virus so they could tell which of those molecules entered the E.coli cells. Since some amino acids contain sulfur in their side chains, if T2 is grown in E.coli with a source of radioactive sulfur, the sulfur will be incorporated into the T2 protein coat making it radioactive. Since DNA has lots of phosphorus in its phosphate (PO4) groups, if T2 is grown in E.coli with a source of radioactive phosphorus, the phosphorus will be incorporated into the viral DNA, making that radioactive. Hershey and Chase grew two batches of T2 and E.coli: one with radioactive sulfur and one with radioactive phosphorus to get batches of T2 labeled with either radioactive S or radioactive P. Then, these radioactive T2 were placed in separate, new batches of E.coli, but were left there only 10 minutes. This was to give the T2 time to inject their genetic material into the bacteria, but not reproduce. In the next step, still in separate batches, the mixtures were agitated in a kitchen blender to knock loose any viral parts not inside the E.coli but perhaps stuck on the outer surface. Hopefully, this would differentiate between the protein and DNA portions of the virus. Then, each mixture was spun in a centrifuge to separate the heavy bacteria (with any viral parts that had gone into them) from the liquid solution they were in (including any viral parts that had not entered the bacteria). The centrifuge causes the heavier bacteria to be pulled to the bottom of the tube where they form a pellet, while the light-weight viral left-overs stay suspended in the liquid portion called the supernatant. In the subsequent step, the pellet and supernatant from each tube were separated and tested for the presence of radioactivity. Radioactive sufur was found in the supernatant, indicating that the viral protein did not go into the bacteria. Radioactive phosphorus was found in the bacterial pellet, indicating that viral DNA did go into the bacteria.

Based on these results, Hershey and Chase concluded that DNA must be the genetic code material, not protein as many poeple believed. When their experiment was published and people finally acknowledged that DNA was the genetic material, there was a lot of competition to be the first to discover its chemical structure.

Discovery of the Structure of DNA:

What was known is that DNA contains a nitrogenous base. There are two kinds of these, which include:

Nucleoside Nucleotide Each nitrogenous base is connected to a molecule of ribose sugar (1 oxygen in DNA) to form a nucleoside like the adenosine in ATP.

Each nucleoside is joined to a PO4 (phosphate group, ) to form a nucleotide like adenosine monophosphate (which can be turned into ATP by adding phosphate groups).

Deoxy Nucleotide People also knew that nucleotides were somehow linked by dehydration synthesis to form DNA, but the exact structure/arrangement was unknown.

In the early 1950s, Rosalind Franklin, an Englishwoman, was doing research which involved bouncing x-rays off crystals of various substances (a process which is called x-ray crystallography or x-ray crystal diffraction), including DNA, then exposing photographic film to the x-rays. She was studying the scatter patterns made by the x-rays bouncing off the crystals of various substances (Unfortunately, she died of cancer soon afterwards, or she might have been more famous). Other people like Linus Pauling were also attempting to figure out the structure of DNA.

Structure of DNA James Watson, a young American scientist was in England working with Francis Crick, another young researcher. Someone showed them Franklins photographs of DNA x-ray crystallography, and from her pictures, they were able to determine that the structure of DNA was organized into a double spiral or double helix. Based on Franklins data, in 1953, Watson and Crick published a paper in which they proposed and described an hypothetical structure for DNA. Subsequent research by many other people has since upheld their hypothesis, and based on subsequent examination of Franklins lab notes and calculations, she was probably within a couple days of coming to the same conclusion when their paper was published. For their discovery, Watson and Crick received the Nobel prize in 1962. In the intervening time, Rosalind Franklin had died in 1958 of ovarian cancer, probably due in large part to her work with x-rays. Since the Nobel prize is not awarded posthumously, people have often wondered if the Nobel committee would have included Franklin if she had still been alive.

Double Helix DNA Replication DNA is a double helix. The outer edges are formed of alternating ribose sugar molecules and phosphate groups. The two strands go in opposite directions (1 up and 1 down). The nitrogenous bases are inside like rungs on a ladder. Adenine on one side pairs with thymine (uracil in RNA) on the other by hydrogen bonding, and cytosine pairs with guanine. Note that the C-G pair has three hydrogen bonds while the A-T pair has only two, which keeps them from pairing wrong. This dictates side-to-side pairing, but says nothing about the order along the molecule. Watson and Crick said this variability along the molecule can account for the variety in the genetic code. Their model also accounts for how DNA can replicate itself. They said the molecule unzips and new matching bases are added in to create two new molecules. They called this semiconservative replication because each new molecule has one old and one new strand of DNA.

DNA mRNA tRNA &rarr Protein:

Here is a list of the mRNA codons and the corresponding amino acids for which they code.

B a s e

B a s e

Transcription and Translation Practice

Here is a DNA gene for some fictitious protein. Transcribe the DNA code to RNA code, then translate the RNA code to an amino acid sequence. It is set up to only accept a 3-letter code, so use the codes sta for START and sto for STOP.

Mutations and Viruses:

Mutations can be caused by a change in the sequence of the nucleotides. Some mutations have more effect than others, depending on where in the code they are and how important that area is to the code. While mutations in some areas of some genes have little effect, sickle cell anemia is caused by a mutation in only one nucleotide. This changes the codon at that location to code for a different amino acid, and that, in turn, significantly changes the shape of the hemoglobin molecules in that persons blood.

When some viruses (especially Herpes viruses, including Chicken Pox and cold sores) infect us, they insert their DNA into our cells DNA, and stay resident in our cells for the rest of our lives. These can potentially become active again either making a person sick again (like Shingles in a person who has had Chicken Pox) or just being shed from a persons body (to infect others) without obvious symptoms of illness (like Mononucleosis). Some kinds of cancer may be caused this way. For example, there is some pretty strong evidence linking genital warts (human papillomavirus, HPV) and cervical cancer.

The AIDS virus does things backwards. This virus contains RNA rather than DNA, yet when it gets into someones cells, it can do reverse transcription and code from its RNA to make DNA which, then, can code to make more virus.

Genetic Engineering Is It Good or Bad?

We now have the knowledge and ability to transfer genes from one organism to another, which seems to have some benefits associated with it, but may also have many yet-to-be-discovered problems associated with it. Because this is all so new, not enough time has elapsed to allow scientists to study/look for any possible long-term effects of genetically-modified organisms (GMOs).

For more information on genetically-modified foods, see Dr.Fankhausers Web page on that topic.

References:

Berkow, Robert, ed. 1999. The Merck Manual. 17th ed. Merck, Sharp & Dohme, Rahway, NJ.

Borror, Donald J. 1960. Dictionary of Root Words and Combining Forms. Mayfield Publ. Co.

Campbell, Neil A., Lawrence G. Mitchell, Jane B. Reece. 1999. Biology, 5th Ed. Benjamin/Cummings Publ. Co., Inc. Menlo Park, CA. (plus earlier editions)

Campbell, Neil A., Lawrence G. Mitchell, Jane B. Reece. 1999. Biology: Concepts and Connections, 3rd Ed. Benjamin/Cummings Publ. Co., Inc. Menlo Park, CA. (plus earlier editions)

Marchuk, William N. 1992. A Life Science Lexicon. Wm. C. Brown Publishers, Dubuque, IA.

There are many Web pages with information relating to the Watson-Crick-Franklin-Wilkins story. Here is a small sample of the many that were found via a search:

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DNA Structure and Function

DNA is extracted from human cells for a variety of reasons. With a pure sample of DNA you can test a newborn for a genetic disease, analyze forensic evidence, or study a gene involved in cancer. Try this virtual laboratory to perform a cheek swab and extract DNA from human cells.

Javascript is required to view this content.

Supported by a Science Education Partnership Award (SEPA) Grant No. R25RR016291 from the National Center for Research Resources, a component of the NIH. The contents provided here are solely the responsibility of the authors and do not necessarily represent the official views of NIH.

APA format: Genetic Science Learning Center (2014, June 22) DNA Extraction. Learn.Genetics. Retrieved September 17, 2015, from http://learn.genetics.utah.edu/content/labs/extraction/ MLA format: Genetic Science Learning Center. "DNA Extraction." Learn.Genetics 17 September 2015 <http://learn.genetics.utah.edu/content/labs/extraction/> Chicago format: Genetic Science Learning Center, "DNA Extraction," Learn.Genetics, 22 June 2014, <http://learn.genetics.utah.edu/content/labs/extraction/> (17 September 2015)

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DNA Extraction - Learn Genetics

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The aim of the project, which also includes the use of health and lifestyle questionnaires, is to match the data collected to diseases that develop over the course of the lives of the volunteers.... Astaxanthin found to reduce oxidation, DNA damage and liver cancer formation 11/12/2013 - Scientific evidence continues to mount showing that astaxanthin is one of the most potent antioxidants yet discovered. A study conducted by researchers from India's National Institute of Pharmaceutical Education and Research found that astaxanthin not only can reduce oxidation of the liver but can actually... Confirmed by science: You really can change your DNA - and here's how 9/21/2013 - If you believe that you are at the mercy of your genetic code, great news, you're not. According to the science of epigenetics (the study of how environmental factors outside of DNA influence changes in gene expression), stem cells and even DNA can be altered through magnetic fields, heart coherence,... Supreme Court rules cops can collect your DNA if they arrest you 6/29/2013 - Your constitutional right to not be searched or detained by law enforcement officials without reasonable suspicion or probable cause has been further eroded by a recent Supreme Court ruling, which now allows police officers to freely collect DNA samples from individuals they arrest in connection with... Monsanto: The worst of the worst 5/30/2013 - Monsanto lies about everything and will commit any atrocity against the people to ensure profits. Recently, the Cornucopia Institute reported about the French farmer that was poisoned by one of Monsanto's "safe" pesticides. Read it for your self. A French farmer who can no longer perform his routine... Junk DNA suspected to be behind destructive neurological diseases 4/24/2013 - Scientists from UC San Francisco have recently bared findings that some DNA that used to be considered as junk, have a crucial role in brain development, and could be linked to a number of devastating neurological ailments. The efforts to finally determine the particular roles of the long-ignored DNA... Vitamin D compound may help skin lotions reduce DNA damage by up to 80 percent 2/9/2013 - Though the mainstream sunscreen and skin care industries have a rather long way to go in correcting certain misinformation propaganda of decades gone by, the market may soon experience at least a slight shift in direction. Initial reports out of Australia indicate that researchers there say a new vitamin... DNA doesn't lie: Happy children become healthy adults 1/19/2013 - It sounds like science fiction but it is a scientific fact. A happy childhood leads to a healthy adult life. This is what scientists found when they examined the effects of childhood adversities to DNA. They found that the tiny protective caps of our chromosomes, which are called telomeres, shorten... Micronutrient deficiencies can cause DNA damage 9/14/2012 - All of us, identical twins excepted, are genetically unique. Of course, everyone's genes encode all the proteins needed for life, but the sum total of all our biochemical processes varies considerably from person to person. One of the consequences of this genetically determined biochemical individuality... 'Junk' DNA found to play crucial role in health or disease 9/13/2012 - Human biology is a mysterious thing, which is why perplexing diseases like high blood pressure, diabetes and psychiatric disorders are so hard to predict and, as is often the case, to treat as well. Another complexity involves understanding how and why one individual might contract a debilitating or... The invisible threat that pulls apart DNA, causing genetic disorders and cancer 6/20/2012 - We are all exposed to electromagnetic radiation constantly on a daily basis from mobile phones, Wifi hot spots, power lines and electrical appliances. The sources of this pollution are many and varied, each having its own range of wavelength, frequency and intensity. How does the artificial electromagnetic... Exercise boosts healthy DNA expression within just a few minutes 3/23/2012 - Exercise truly is a vital component of good health, as was once again illustrated in a recent study published in the peer-reviewed journal Cell Metabolism. Researchers from the Karolinska Institute in Stockholm, Sweden, the University of Copenhagen in Denmark, and Dublin City University in Ireland found... Just a few minutes of daily exercise alters DNA to help prevent chronic disease 3/16/2012 - Many people think the genes they inherited at birth are static and predetermine their fate for the remainder of their life. Extensive research into the science of epigenetics is providing startling evidence that this thought process is grossly outdated, and our individual DNA is dynamic and continually... Study: Roundup diluted by 99.8 percent still destroys human DNA 2/23/2012 - A new study published in the journal Archives of Toxicology proves once again that there really is no safe level of exposure to Monsanto's Roundup (glyphosate) herbicide formula for genetically-modified organisms (GMOs). According to the new findings, Roundup, which is applied by the tens of thousands... Grape seed extract targets cancer cells by damaging DNA repair pathway 2/7/2012 - Researchers from the Colorado Cancer Center reporting in the prestigious journal Carcinogenesis explain the unique mechanism exerted by grape seed extract to destroy cancer cells that target the head and neck. More than half a million people worldwide will fall victim to squamous cell carcinoma involving... The HPV vaccine - what do you really know about it? 10/14/2011 - If you are considering vaccinating your child with an HPV vaccine, what information have you read, and what questions have you asked?What do you KNOW about the human papillomaviruses (HPV) which the medical profession says causes cervical cancer? If you are going to vaccinate your child on the word... Genetically modified organisms inject DNA into intestinal bacteria 6/24/2011 - Food that contains genetically engineered organisms can transfer genetic material into the DNA of bacteria in the intestinal tract leading to a myriad of health consequences. Responsible scientists have been warning about the potential dangers of releasing genetically modified organisms into the food... Study: Antioxidant blend protects against radioactive DNA damage 3/31/2011 - New research presented at the 36th annual meeting of the Society of Interventional Radiology in Chicago, Ill., has revealed the incredible power of antioxidants to protect the body against the damaging effects of radiation. Researchers from the University of Toronto, Ontario, Can., department of medical... After touching your junk, TSA now wants to scan and harvest your DNA 2/28/2011 - As if it's not enough for the TSA to feel you up at the airport, now they're experimenting with rapid results DNA scanners that can scan and analyze your DNA using just a drop of saliva. Spit at the TSA agent who is molesting you, in other words, and they can use that saliva to scan your DNA and then... Man-caused changes to our DNA threaten our present health and future survival 1/17/2011 - Thanks to toxins, radiation, poor diet, genetically modified food and unhealthy lifestyles, human DNA and gene expression are being changed in unnatural and unhealthy ways. Besides threatening our present health, the changes are also threatening our future viability as a species. Scientists are increasingly... Invisible DNA body spray technology may soon be installed at a business near you 10/22/2010 - A U.K. company has developed a technology that it says will help deter thieves from robbing local businesses. SelectaDNA Spray, as it is called, coats robbers with an invisible DNA mist that cannot be washed off and remains present on skin and hair for weeks, allowing authorities to better link culprits... Bovine DNA found on chicken meat 8/26/2010 - Tests carried out in Ireland have found traces of cow and pig DNA in chicken products being sold in grocery stores, raising concerns over unlabeled cross-species ingredients. The issue first came to light in December, when the United Kingdom's Food Standards Agency (FSA) found traces of pork proteins... Dead cow carcasses "resurrected" to produce cloned beef 8/16/2010 - We already know that cloned beef has entered the food supply both in the United States (http://www.naturalnews.com/023718_food_beef_cloned.html) and the UK (http://www.naturalnews.com/029411_cloned_beef_food.html). Now, thanks to revelations from JR Simplot, a U.S. company specializing in the cloning... Understand DNA Damage and Repair 5/7/2010 - Most people today are consistently exposed to substances that are known to damage our DNA. Radiation, plastics, cigarette smoke, chemicals in soft drinks, pesticides, and many more common substances have all been found to damage our DNA. It's unfortunate because when our DNA is damaged, we subject ourselves... The government has your baby's DNA! 4/25/2010 - According to Brad Therrell, director of the National Newborn Screening & Genetics Resource Center, all babies born in the United States are required to be screened for a host of genetic diseases. The government has mandated that all newborns be evaluated genetically to see whether or not they might... Vitamin and Mineral Shortages Cause Degenerative Diseases 4/1/2010 - When micronutrients like vitamins and minerals are in short supply they are temporarily reserved for the most essential organs, at the expense of less pressing tasks. This is a survival mechanism, an example of physiological triage (1). Neglecting less essential functions on occasion may do no harm... Stunning Research Shows High Potential for DNA Damage from Nanoparticles 3/27/2010 - Nanoparticles may be able to damage the DNA of cells without ever coming into contact with it, according to a study conducted by researchers from the Bristol Implant Research Center and published in the journal Nature Nanotechnology. Nanoparticles are particles so small that they have fundamentally... Two High School Students Find Epidemic of Mislabeled Foods 2/10/2010 - Two high school students, Brenda Tan and Matt Cost at the Trinity School of Manhattan, gathered 151 DNA samples from foods and objects in their and neighbor`s homes as part of a science project. Of the samples, a large percentage were found to not be what their packaging said they were - they were mislabeled... Israeli Scientists Show DNA Evidence Can be Fabricated 1/29/2010 - Scientists from the Tel Aviv, Israel-based company Nucleix have demonstrated that it is possible to create fake DNA samples and plant them as evidence at a crime scene, in a paper published in the journal Forensic Science: International Genetics. "You can just engineer a crime scene," said lead researcher... Full-body scanners used on air passengers may damage human DNA 1/11/2010 - In researching the biological effects of the millimeter wave scanners used for whole body imaging at airports, NaturalNews has learned that the energy emitted by the machines may damage human DNA. Millimeter wave machines represent one of two primary technologies currently being used for the "digital... The Bill Nobody Noticed: National DNA Databank 12/18/2008 - In April of 2008, President Bush signed into law S.1858 which allows the federal government to screen the DNA of all newborn babies in the U.S. This was to be implemented within 6 months meaning that this collection is now being carried out. Congressman Ron Paul states that this bill is the first step... Magnesium: The Lamp of Life 11/18/2008 - Inside chlorophyll is the lamp of life and that lamp is magnesium. The capture of light energy from the sun is magnesium dependent. Magnesium is bound as the central atom of the porphyrin ring of the green plant pigment chlorophyll. Magnesium is the element that causes plants to be able to convert light... Curcumin Tempers Arsenic Toxicity Through DNA Repair 9/10/2008 - Curcumin, the active ingredient in the spice turmeric is effective against the harmful impact of arsenic according to a recent study reported in the Journal of Clinical Biochemistry and Nutrition. Arsenic is a poison that can be fatal to humans. The study investigated whether curcumin could counteract... New Study Indicates DNA Can Be Altered Through Diet and Exercise 9/10/2008 - A new study that was recently published sheds more evidence to what many have been saying for a long time, that DNA does not control the body or predestine you to being overweight, ill, sick, weak or anything else, but that the majority of our health and destiny lies within our own power. Here is... Natural Sweetener Stevia Loaded With Antioxidants; Protects Against DNA Damage 7/30/2008 - Extracts from the leaf of the Stevia plant have been found to be high in antioxidants that prevent the DNA damage that leads to cancer, according to a new Indian study published in the Journal of Agricultural and Food Chemistry. "These results indicate that Stevia rebaudiana may be useful as a potential... DNA: Toppling the Evolutionary 'Tree of Life' 6/22/2008 - In 1953, a once impossible achievement was accomplished, that being the unraveling and understanding of the DNA molecule, also called deoxyribonucleic acid. Two scientists, James Watson and Francis Crick, accomplished what was thought to be impossible. The discovery of the double helix code hidden within... New Legislation Calls for Government Ownership of DNA 4/29/2008 - An article published in the April 4, 2008 issue of World Net Daily outlines a plan that has state and federal governments staking claim to the ownership of every newborn's DNA in perpetuity. This Orwellian like plan is advancing under the radar of most privacy rights activists, as well as that of most... DNA and Mitochondrial Time Bombs: Uranium and Mercury 3/3/2008 - Hyperinsulinemia may promote mammary carcinogenesis. Insulin resistance has been linked to an increased risk of breast cancer and is also characteristic of type 2 diabetes. Diabetes and cancer are both expanding almost exponentially in the world today and can in part be traced to the increasing radiation... U.S. authorities to start massive DNA gathering from population 2/15/2007 - The federal government is finalizing rules that would encourage the collection of DNA samples from everyone arrested by federal authorities, as well as any illegal immigrant detained by federal agents for any reason. A little-noticed amendment to last month's renewal of the Violence Against Women... Genetic code of human race is deteriorating due to environmental factors 12/1/2006 - Small damages to sequences in the human genome are causing evolutionary changes in our DNA. Recent findings from a Japanese group prove that a common form of DNA damage caused by oxidation is a primary cause of mutagenesis -- damage to DNA during the genome replication process. As a result, the human... See all 161 DNA feature articles. 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Your DNA is what makes you uniquely you. It's that double helix that your genes are made of. Your DNA accounts for why you resemble your parents and it distinguishes you from your pet frog and from everybody else.

DNA stands for deoxyribonucleic acid, sometimes called "the molecule of life," as almost all organisms have their genetic material codified as DNA. Since each persons DNA is unique, "DNA typing" is a valuable tool in connecting suspects to crime scenes. You can also use the word less scientifically, as in its just not in my DNA to sit through six hours of meetings.

Definitions of DNA

1

DNA is the king of molecules

a segment of DNA containing adjacent genes including structural genes and an operator gene and a regulatory gene

single-stranded DNA that is complementary to messenger RNA or DNA that has been synthesized from messenger RNA by reverse transcriptase

DNA that is not incorporated into the genome but is replicated together with the genome (especially in bacterial cells)

sequence of a gene's DNA that transcribes into protein structures

sequence of a eukaryotic gene's DNA that is not translated into a protein

stretches of DNA that do not code for genes

genetically engineered DNA made by recombining fragments of DNA from different organisms

an end of DNA in which one strand of the double helix extends a few units beyond the other

a segment of DNA that can become integrated at many different sites along a chromosome (especially a segment of bacterial DNA that can be translocated as a whole)

cDNA copy of the RNA genome of a retrovirus; the genetic material of a virus as incorporated into and able to replicate with the genome of a host cell

double-stranded cDNA

a naturally occurring or synthetic compound consisting of large molecules made up of a linked series of repeated simple monomers

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DNA - Dictionary Definition : Vocabulary.com

The CBS drama "CSI: Crime Scene Investigation" routinely draws more than 20 million viewers per episode, making it one of television's greatest successes. The show's popularity owes a great deal to the writers and actors who bring the stories to life. But another intriguing element is the cutting-edge technology used by the Las Vegas crime lab trying to solve crimes. Collecting and analyzing DNA evidence tops the list of the lab's forensic toolkit, and its ubiquity in shows like "CSI" and "Cold Case" has increased public awareness to the point that many jurors in real-world courtrooms expect to see DNA evidence presented -- whether a case calls for it or not.

It's hard to believe that DNA evidence has come so far so fast. The techniques that make it possible to identify a suspect using his or her unique genetic blueprint have only been around since 1985. That's when Alec Jeffreys and his colleagues in England first demonstrated the use of DNA in a criminal investigation. Since then, DNA evidence has played a bigger and bigger role in many nations' criminal justice systems. It has been used to prove that suspects were involved in crimes and to free people who were wrongly convicted. And, in the United States, it has been integral to several high-profile criminal cases.

At the heart of DNA evidence is the biological molecule itself, which serves as an instruction manual and blueprint for everything in your body (see How Cells Work for details). A DNA molecule is a long, twisting chain known as a double helix. DNA looks pretty complex, but it's really made of only four nucleotides:

These nucleotides exist as base pairs that link together like the rungs in a ladder. Adenine and thymine always bond together as a pair, and cytosine and guanine bond together as a pair. While the majority of DNA doesn't differ from human to human, some 3 million base pairs of DNA (about 0.10 percent of your entire genome) vary from person to person.

In human cells, DNA is tightly wrapped into 23 pairs of chromosomes. One member of each chromosomal pair comes from your mother, and the other comes from your father. In other words, your DNA is a combination of your mother's and your father's DNA. Unless you have an identical twin, your DNA is unique to you.

This is what makes DNA evidence so valuable in investigations -- it's almost impossible for someone else to have DNA that is identical to yours. But catching a criminal using DNA evidence is not quite as easy as "CSI" makes it seem, as this article will demonstrate. Our first step in exploring DNA evidence is the crime scene -- and the biological evidence gathered there by detectives.

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How DNA Evidence Works - HowStuffWorks

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Find out what percent of your DNA comes from populations around the world, ranging from East Asia, Sub-Saharan Africa, Europe, and more. Break European ancestry down into distinct regions such as the British Isles, Scandinavia and Italy. People with mixed ancestry, African Americans, Latinos, and Native Americans will also get a detailed breakdown.

What will your Ancestry Composition look like?

Your personalized 23andMe web account provides secure and easy access to your information, with multiple levels of encryption and security protocols protecting your personal information. See our Privacy Policy for more information.

The Genetic Information Nondiscrimination Act (GINA) is U.S. federal legislation that protects Americans from discrimination (in health insurance and employment decisions) on the basis of genetic information. Click here to learn about how GINA protects your genetic privacy.

23andMe is a DNA analysis service providing information and tools for individuals to learn about and explore their DNA. We use the Illumina HumanOmniExpress-24 format chip (shown here). Our chip consists of a fully custom panel of probes for detecting genetic variations. The selection was made to maximize the number of ancestry features available to customers as well as offer flexibility for future research.

All of the laboratory testing for 23andMe is done in a CLIA-certified, CAP-accredited laboratory in the United States.

We're changing the way the world sees genetics. Read how the media is talking about 23andMe.

January 2015

We have the ability to do research broadly.

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January 2015

Conducted the first genome-wide association study on motion sickness in almost 80,500 people in its database.

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January 2015

23andMe data may help drug companies better target their trials toward patients whose genetics make them more likely to do well on a drug, or less likely to suffer adverse reactions.

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December 2014

Now for the first time, a large-scale study published using genetic data voluntarily submitted to biotechnology company 23andMe sheds light into the ancestry of three groups.

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December 2014

A team of scientists published the biggest genetic profile of the United States to date, based on a study of 160,000 people.

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