Dna Definition and 386 Threads

Deoxyribonucleic acid ( (listen); DNA) is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.
The two DNA strands are known as polynucleotides as they are composed of simpler monomeric units called nucleotides. Each nucleotide is composed of one of four nitrogen-containing nucleobases (cytosine [C], guanine [G], adenine [A] or thymine [T]), a sugar called deoxyribose, and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds (known as the phospho-diester linkage) between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. The nitrogenous bases of the two separate polynucleotide strands are bound together, according to base pairing rules (A with T and C with G), with hydrogen bonds to make double-stranded DNA. The complementary nitrogenous bases are divided into two groups, pyrimidines and purines. In DNA, the pyrimidines are thymine and cytosine; the purines are adenine and guanine.
Both strands of double-stranded DNA store the same biological information. This information is replicated as and when the two strands separate. A large part of DNA (more than 98% for humans) is non-coding, meaning that these sections do not serve as patterns for protein sequences. The two strands of DNA run in opposite directions to each other and are thus antiparallel. Attached to each sugar is one of four types of nucleobases (or bases). It is the sequence of these four nucleobases along the backbone that encodes genetic information. RNA strands are created using DNA strands as a template in a process called transcription, where DNA bases are exchanged for their corresponding bases except in the case of thymine (T), for which RNA substitutes uracil (U). Under the genetic code, these RNA strands specify the sequence of amino acids within proteins in a process called translation.
Within eukaryotic cells, DNA is organized into long structures called chromosomes. Before typical cell division, these chromosomes are duplicated in the process of DNA replication, providing a complete set of chromosomes for each daughter cell. Eukaryotic organisms (animals, plants, fungi and protists) store most of their DNA inside the cell nucleus as nuclear DNA, and some in the mitochondria as mitochondrial DNA or in chloroplasts as chloroplast DNA. In contrast, prokaryotes (bacteria and archaea) store their DNA only in the cytoplasm, in circular chromosomes. Within eukaryotic chromosomes, chromatin proteins, such as histones, compact and organize DNA. These compacting structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.

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  1. K

    How to Create Tetramers or Hexamers from a 96-Base Long DNA Sequence?

    I have a DNA sequence of 96 bases long. I want to make a tetramer/hexamer of this sequence. Is there any standard protocol available for this?
  2. T

    Exploring the Endosymbiont Hypothesis: Beyond DNA Resemblance

    In Bio II AP our teacher assigned us an assignment to read about the Endosymbiont Hypothesis. Very interesting indeed. Now I know the basic facts...prokaryotes being engulfed by larger prokaryotes forming organelles such as the power houses, mitochondrian, and cholorplasts. But besides DNA...
  3. J

    New Dna Discovery,what Do You Think

    http://www.luisprada.com/Protected/russian_dna_discoveries.htm russian scientist discovered that affirmations directly affect dna and some more info about hypercommunication, which explains telepathy and other esp phenomenon.
  4. N

    DNA & Heredity: Can DNA Change?

    i thought i got some refused thing.can DNA change?if they cannot change, why we don't like as a cave dweller or like a monkey?i mean the body .
  5. C

    Modifying Human DNA: Is It Possible?

    Is it possible to modify human dna to get more sturdier humans?
  6. agro

    The Mechanism of DNA Replication

    I once read a 1997 physics book. At the end of the 'static electricity' chapter, it explains the mechanism of DNA replication and protein synthesis (in which static electrical force plays a critical role). However, it says something like 'this model has not been seen in action. It is consistent...
  7. R

    What is the relationship between chromosomes, genes, and DNA?

    Way back in the dark ages when I went to high school, we where taught that humans had 32(?) chromosomes and that each chromosome contained individual genes which was what actually passed on characteristics and traits like eye color etc. So now there is DNA and the humane genome is billions of...
  8. wolram

    The Secrets of Regeneration: DNA and Re-Growth

    When cut in half they can regrow the severed part, but how? is the information that enables this re growth encoded in the DNA, what mechanism initiates this re growth.
  9. M

    Evidence for DNA Panspermia Theory?

    What would we be looking for in terms of chemical evidence when this craft returns in 2006 with samples? Anyone know, and what field of science would know best, chemistry? Biology?
  10. O

    Chromosomes in DNA: Structure unclear

    DNA in Chromosomes: Structure unclear I am a little unclear on the structure of chromosomes and the DNA within, and thought maybe you could point me in the right direction. It's a little difficult to word this, so I hope it makes sense. This site and most other sites basically state...
  11. Loren Booda

    Exploring DNA Rings: Complete Structures and Their Occurrence

    Does DNA ever occur as a complete uniform ring, rather than a(n approximate) strand?
  12. D

    Electric Forces and Electric Fields in DNA

    I need help with the following, I don’t even know how to start A molecule of DNA ( deoxyribonucleic acid) is 2.17μm long. The ends of the molecule become singly ionized – negative on one end, positive on the other. The helical molecule acts as a spring and compresses 1.00 % on becoming...
  13. P

    DNA structures and its siblings

    I would like to ask a question about PNA and Morpholino... I am sorry, I look at their structure images but I still couldn't see anything that can be called similarities. The Morpholino has ring structure which is the same as DNA but PNA has no rings at all... Would you please explain a...
  14. I

    Can Pollution Cause Genetic Mutations in Future Generations?

    a new study at McMasters University in Toronto has discovered that polution can alter your DNA, the research were done on mice, three categories, the first category lived in the middle of an industrial zone brething in heavily poluted air, the second lived on a farm with clean air, and the third...
  15. iansmith

    Does Mitochondrial DNA Recombine?

    http://www.biomedcentral.com/news/20040514/01
  16. A

    DNA in Eukaryotes: Open Ended Strings vs Closed Loops

    Why is the DNA in eukaryotes an open ended string rather than a closed loop?
  17. A

    Mouse born without male's DNA

    Mouse "born" without male's DNA! Just kidding :)
  18. A

    Twins: Same DNA? Maternal Connection?

    Do twins, that split from the same egg (is this maternal?) have the exact same DNA?
  19. A

    How Does DNA Code for Proteins to Form Complex Shapes Like Viruses?

    Ok, so how does DNA build things? Say, even something as simple as a virus. The virus inserts its DNA or RNA or whatever, and it's coded into proteins. So how does the protein make a shape? Like in that T4 virus that looks like the lunar lander thing, how do the proteins assemble into the...
  20. T

    Body's kundalini spiral bands are DNA of The Universe

    http://www.Givnology.com/wholy.htm Sure, that's simple. Focus on bringing in lunar nose, then solar nose, and be the DNA microcosm of the universe, surrounded by spiraling energy bands (not snakes!), and finally consumated in the crown where they're "making out." Well at least there is a...
  21. M

    What is the problem with a model of parallel evolution?

    In my less than deep undestanding of the biological sciences I understand there is an Axiom that say that the mechainsim of DNA goes in one direction. The DNA will evolve and change and impose itself on the organism, but the process does not work in reverse. Of course thee was the retrovirus...
  22. Jeebus

    Are Nucleotide Sequences in DNA Linked to Gene Mutations and Inheritance?

    How does the sequence of nucleotides in DNA relate to the chemical nature of genes, mutations, and the way genes are inherited?
  23. T

    DNA: What Are the Key Differences Between Prokaryotes and Eukaryotes?

    I would like to know what DNA really is. How is it formed or at what stage in cellular development does it come about. Is it contained within a Gene or is it separate? Is it the determini9ng factor as to a Humans' physical and mental traits? Thanks for helping if possible.
  24. O

    DNA used to create self-assembling nano transistor

    DNA nano-technology is rapidly coming to a point in which applications for mankind will have enormous implications. It now becomes evident that mankind can manipulate DNA that will eventually change the way we live, our health and the world around us...
  25. Dal

    DNA - How Different Genes Coexist in Our Bodies

    So,... this strands of DNA is what makes everyone of us unique and they're in every organs, tissues, blood...etc right? When there is an organ transplant, the part(or organ) that you're accepting has its own genetic stature so doesn't the body reject the new part? Once you acquired a new...
  26. S

    Toy DNA Sequencer: What's the Future of Tech?

    What is the World Coming To?
  27. R

    What is the best way to handle PCR fragments without damaging them?

    I ran a PCR last week but did not get around to running the AGE until this week, so the PCR product sat for a roughly a week at -4*C. What are the odds that all my DNA is at the bottom or stuck to the sides? A friend of mine just suggested this to me, or I would have vortexed it before running...
  28. eagleone

    Exploring Bio and DNA Computers: Current Research & Progress

    I’m interested in current state and progress_point of research in field of using DNA and other Bio materials in developing informational systems (or applying it in some areas/ researches of IT). There’s lot’s of talking going on involving this subject, but no real information. Using google to...
  29. STAii

    How do enzymes locate missing nucleotides during DNA replication correction?

    Greetings. I just have a small question about DNA replication correction. My textbook states (might contain errors of translation): Now my question is about locating the place of the DNA error. Locating the place of a wrong nucleotide might seem logical, but how can the enzyme locate the...
  30. R

    How Does Non-locality Influence Our Perception of Remote Sensing Images?

    Metrics, Dimensions, DNA In order to understand the images processed and viewed in remote sensing it is important to understand where these images are located, as products, and what the scaling for these domains actually constitutes in the multidimensional time-series. Non-locality theory...
  31. Ivan Seeking

    DNA computer unbeaten at tic tac toe: Nature.com

    http://www.nature.com/nsu/030818/030818-9.html
  32. Greg Bernhardt

    What is considered the native form of DNA?

    What is considered the native form of DNA?
  33. T

    98.75% positive = negative? DNA paternity testing

    I'm trying to prove that my daughter is my daughter. We just did DNA testing, but either me or my daughter has a mutation in our DNA and the lab is having a hard time coming up with an answer. They said that they are 98.75% sure that I'mno the father, but they won't say I'm the father unless...
  34. W

    Can DNA testing reveal a person's ethnic origin?

    Is this possible? If so, must the person being tested have a significant percentage to be identified? I am unsure about one of my great-great grandparents lineage, and would like to know, since census records cannot be found. I have heard about something like this, I believe, something to do...
  35. Another God

    Can DNA Be Supercoiled While Wrapped Around Histones?

    Can DNA be supercoiled while it is wrapped around Histones? We are often shown in Biology classes electron Photographs of Supercoiled DNA. Would this DNA in the picture be completely free of Histones? Or could the DNA visualised in the picture be supercoiled DNA already in its condensed...
  36. Monique

    DNA Methylation: MetC to T Transition Mechanism

    I heard that a methylated cytosine converts into a thymine by the following mechanism: The metC during the replication of DNA is place w/ an A opposite, and after the second replication you get what looks like a C to T transition. But isn't the metC to T transition caused by the...
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