DNA renaturation curves occasionally show three distinct phases of renaturation. In this p...

DNA renaturation curves occasionally show three distinct phases of renaturation. In this plot, DNA renaturation is plotted against “C0t” (initial concentration times time of renaturation, essentially a measure of relative renaturation time).

(a) Identify each part of this plot that corresponds to reannealing of (1) unique sequences, (2) moderately repetitive sequences, and (3) highly repetitive sequences.

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 (b) Suppose that you cloned a single-copy gene, such as the gene for dihydrofolate reductase (DHFR), and subjected this to renaturation analysis. Sketch the curve you might expect.

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 (c) Suppose that you cloned the DHFR cDNA instead of genomic DNA. Would you expect this to reanneal (1) more slowly, (2) more rapidly, or (3) at the same rate as genomic DNA? Briefly explain your answer.