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Describe replication and the purpose of replication.
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Replication is the process by which a double-stranded DNA molecule is copied or duplicated forming two identical molecules of DNA. DNA is the chemical compound found in the chromosomes of living things. By first copying DNA during interphase in the cell cycle, when mitotic division occurs later, each new daughter cell will have the full complement of DNA it needs to carry out its life processes. Replication allows the species number of chromosomes to remain constant from generation to generation. Picture DNA like a zipper that is closed. When the zipper is unzipped, each side is open and the teeth of the zipper are exposed. DNA unwinds due to enzymatic action and each side of the double helix is exposed. Its nitrogenous bases which were held together in the center(like teeth in a zipper) are now separated. Each subunit of DNA is called a nucleotide containing a phosphate and sugar group which make up the backbone of the DNA and with one of four nitrogenous bases--adenine, thymine, cytosine and guanine. Since its the bases that join in the center of either side of this double helix, they pair according to base pairing rules--adenine pairs with thymine(and visa versa) and cytosine pairs with guanine(and visa versa). Once the DNA double helix is unwound(like opening a zipper) free nucleotides in the cell will join to exposed nucleotides in the original DNA molecule, on both sides of the template. When the process of replication is complete, two identical DNA molecules will be the end result. These can be enclosed in the two daughter cells that form after mitotic division and these new cells can carry out their life processes according to the DNA blueprint. The link below has an excellent visual of DNA replication.
Posted by trophyhunter1 on July 18, 2012 at 12:14 PM (Answer #1)
Middle School Teacher
Replication is the process by which genetic amterial produces new genetic material. DNA, which stands for deoxyribonucleic acid, is housed in eukaryotic cells in a structure called the nucleus. These strands of DNA are very long, and very complex. The DNA resembles a twisted ladder formation, sometimes referred to as a double-helix, with two side rails and rungs, or steps in the middle. The DNA strand is formed by a series of nucleotides, which have a sugar, a phosphate, and one of four alternating bases. In the process of replication, the DNA strand splits, at what is called a point of origin, down the middle, separating the union of the two bases that form the rungs. Each half of the DNA strand is now used as a template to assemble new DNA, by having appropriate nucleotides drawn in to match to the existing template. The four bases are guanine, cytosine, adenine, and thymine. They pair to each other in that order, guanine to cytosine, and ademine to thymine. So, the purpose is to generate to strands of DNA identical to the preexisting DNA, and the process is as described above.
Posted by bandmanjoe on July 18, 2012 at 4:21 PM (Answer #2)
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