Ap Bio Dbq

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. Information transfer is fundamental to all living organisms. For the three following examples, explain in detail how the transfer of information is accomplished. a. The genetic material in one eukaryotic cell is copied and distributed to two daughter cells. Eukaryotic cells go through Interphase and Mitosis. Interphase is further subdivided into 3 stages, G1 (first gap), S (synthesis of DNA), and G2 (second gap). In all 3 sub phases cell growth happens and organelles like mitochondria are replicated. DNA, however, is only synthesized during the S phase. DNA replication is started by Helicase which unwinds the double helix at replication forks. Topoisomerase is used to loosen the tension at the ends of the bubble, in order to correct for over winding ahead of the replication forks. Primase then synthesizes an RNA primer which the DNA polymerase III will use to lay down bases, synthesizing a new strand. DNA polymerase I will then remove the primer and DNA Ligase will join ends of DNA synthesized from different replication forks. Because DNA can only synthesize from 5'->3', there is a leading strand and lagging strand which creates Okazaki fragments that are later joined together by DNA Ligase. After DNA is replicated proofreading enzymes will check and repair any mistakes that occurred during replication. After S phase is the G2 phase where the cell grows even larger. G2 is followed by mitosis, which is subdivided into 5 parts: prophase, metaphase, anaphase, telophase, and cytokinesis. In prophase, chromatin condenses and the nucleoli disappears. What we know as chromosomes, which consist of two identical sister chromatids joined together at centromers, begin to appear. Mitotic spindle is formed and the centromers start moving to opposite poles, propelled by the lengthening microtubules that they shoot out. In metaphase, the longest stage of mitosis, the chromosomes line up on the metaphase plate and the centromeres have already migrated to opposite poles....
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