Biochemistry 2280A Lecture Notes - Lecture 15: Chromosome, Thymidine Triphosphate, Chain Termination
15 Oct 2017
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Starting from a single cell, humans must generate many billions of copies of their dna throughout their lifetimes. Dna must be copied, or replicated, with great accuracy. During replication of dna, each strand of a double helix serves as a template for synthesis of a new dna strand. The enzyme dna polymerase (movie 6. 1) makes the new strand complementary to the template, according to the watson-crick base pairing rules. For example, when a is on the template strand, t is added to the strand being synthesized (fig 6-2, p. 198). Replication of dna is said to be semi-conservative, meaning that each of the two double helices resulting from replication contains one strand from the original double helix (fig 6-3, p. 199). This was demonstrated in an elegant experiment by meselson and stahl, who labeled replicating bacterial cells with 15n and used centrifugation to. Weigh the bacteria"s double-stranded and single-stranded dna after various generations had passed (see p. 200-202).
