Human DNA Analysis
Deoxyribonucleic acid (DNA) is the structure in the cells that contain the genes for protein synthesis. DNA holds the code that is necessary for life. All cells contain DNA. Some viruses contain DNA as well. These molecules are comprised of a sugar, phosphate and a base. Humans have 23 pairs of chromosomes that contain the DNA molecules.
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Base
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The central component in DNA that hydrogen bonds the double helix is the base. There are four bases in DNA: adenine, guanine, cytosine, and thymine. Each of these bases is abbreviated in DNA models as A, G, C and T. These bases are a part of the genes that are transcribed to RNA. Nitrogenous bases in a certain sequence make up the gene. If these bases are in the wrong order, the gene is mutated and the RNA and protein transcribed from the DNA may not function properly.
Sugar
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Part of the backbone of the DNA molecule is a five carbon sugar. A five carbon sugar is termed "ribose." The ribose only has 3 oxygens on the carbons, which is why DNA is termed "deoxyribose." Additionally, the carbons are numbered 1-5. The numbering of the carbons helps determine where the base will bond. It also determines where the phosphate bonds, which is also a part of the DNA backbone.
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Phosphate
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The final part of the backbone is the phosphate group that binds to the sugar. The phosphates bond the the 3 and 5 carbons. These phosphates connect the sugars and hold the DNA strand together. The phosphates are bonded using an ester bond. An ester bond with a phosphate is termed a "phosphodiester" bond. The phosphates on the backbone are what make DNA a negatively charged molecule.
Anti-parallel
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The two strands of DNA are anti-parallel. What this means is that one strand is placed with the trailing phosphate at one end and the other strand is placed with the trailing phosphate at the other end of the DNA molecule. This creates a complementary structure where each DNA strand hydrogen bonds together to form the helix.
Complimentary
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The strands of the DNA are said to be complimentary. The nitrogenous bases that make up the center of the DNA strands hydrogen bond with specific bases. The adenine only bonds to a thymine. The cytosine only bonds to a guanine. There are three hydrogen bonds between a guanine and a cytosine. Conversely, there are only two hydrogen bonds between a thymine and an adenine.
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