DNA

The polymer that makes you you!

Deoxyribonucleic acid polynucleotide

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http://www.ncbi.nlm.nih.gov/About/primer/genetics_genome.html


FUN DNA GAME! play! http://nobelprize.org/educational_games/medicine/dna_double_helix/dnahelix.html</span>

DNA is a natural polymer that plays a huge role in all plants and animals. DNA can be found in the nucleus of every human cell. It determines all of the physical characterisics through genes. Genes are a sequence of nucleotides that tell how a specific protein is to be made. The proteins then carry out all of the functions of living organisms.

The monomers of DNA are called nucleotides. Each nucleotide consists of a 5-carbon sugar (deoxyribose), a base (either a purine or a pyramidine), and a phosphate. There are four bases: Adenine, Thymine, Cytosine, and Guanine. The purines, Adenine and Guanine, have 5 carbons and the pyrimidines, Thymine and Cytosine, have 3 carbons. Purines are nitrogen containing bases consisting of two rings and Pyrimidines are nitrogen containing bases with just one ring consisting of carbon and nitrogen.

One of the four bases is attached to the sugar and phosphate. The nucleotides are linked covalently between the 3' carbon atom and the 5' carbon atom. Covalent bonding occurs between the sugar of one nucleotide to the phosphate in the backbone of the next. Each nucleotide is then paired up with their corresponding base (A to T and C to G). A weak hydrogen bond is the only thing that holds the two base pairs together, which makes DNA very easy to split and replicate. The linked nucleotides become a polynucleotide, the polymer of DNA.
DNA.gif
DNA Structure: http://www.chemistry.nmsu.edu/studntres/chem435/Lab4/intro.html
Actg4.gif
Nucleotides: http://www.ncbi.nlm.nih.gov/About/primer/genetics_genome.html

Hydrogen bonds hold the nucleotide bases together. The bonds are formed by a weak polar charge, which is an area of attraction between the positive and negative areas of two molecules. There is no sharing or trade of electrons, which is why a hydrogen bond has only 5% of the strength of a covalent bond.

DNA is shaped like a twisted ladder, called a double helix. The double helix form allows DNA to replicate itself. The helix splits in half, and each remaining half becomes a template for a new string of DNA. The A matches to the T (and C to G), just as before, therefore producing an exact replica of the original double helix.

After an expirement
led by Gregor Mendel in 1857, there was a great increase in the study of genetics. In 1953, James Watson and Francis Crick were the first two scientists to put together a model of the DNA molecule.

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Double Helix: http://ghr.nlm.nih.gov/handbook/illustrations/dnastructure.jpg



Citations
"Deoxyribonucleic Acid". National Human Genome Research Institute. 12 May 2008 <[[http://www.genome.gov/25520880%3C/span%3E%3Cspan|http://www.genome.gov/25520880<span]] style="FONT-FAMILY: Georgia, serif">>.


"What is a Genome?". National Center for Biotechnology. 13 May 2008 <http://www.ncbi.nlm.nih.gov/About/primer/genetics_genome.html</span>

"What is DNA?". U.S. National Library of Medicine. 12 May 2008 <[[http://ghr.nlm.nih.gov/handbook/basics/dna%3C/span%3E%3C/span|http://ghr.nlm.nih.gov/handbook/basics/dna</span]]>


Hallick, Richard. "Introduction to DNA Structure". 14 May 2008 <[[http://www.blc.arizona.edu/Molecular_Graphics/DNA_Structure/DNA_Tutorial.HTML%3C/span%3E%3Cspan|http://www.blc.arizona.edu/Molecular_Graphics/DNA_Structure/DNA_Tutorial.HTML<span]] style="COLOR: #072cb6; FONT-FAMILY: Georgia, serif">>.

Freudenrich, Ph.D., Craig. "How DNA Works." 20 March 2007. HowStuffWorks.com. <[[http://science.howstuffworks.com/dna.htm%3C/span%3E%3Cspan|http://science.howstuffworks.com/dna.htm<span]] style="COLOR: #072cb6; FONT-FAMILY: Georgia, serif">> 14 May 2008.

"Nucleotide." ISCID Encyclopedia of Science and Philosophy. 2008. International Society for Complexity, Information, and Design. 14 May 2008 <[[http://www.iscid.org/encyclopedia/Nucleotide%3C/span%3E%3Cspan|http://www.iscid.org/encyclopedia/Nucleotide<span]] style="COLOR: #072cb6; FONT-FAMILY: Georgia, serif">>

"DNA History". 14 May 2008 <[[http://library.thinkquest.org/20830/Textbook/HistoryofDNAResearch.htm%3C/span%3E%3Cspan|http://library.thinkquest.org/20830/Textbook/HistoryofDNAResearch.htm<span]] style="COLOR: #072cb6; FONT-FAMILY: Georgia, serif">>.