11.14 A C0t curve represents the fraction of DNA remaining single stranded in a renaturation reaction, plotted as a function of DNA concentration x time (C0t). This graph is a typical C0t curve for a prokaryotic organism.

there are five students in the class named Scott, this name will appear on ten cards; so the chance of drawing out two cards at random bearing the name Scott is fairly high. On the other hand, if there is only one Susan in the class, this name will appear on only two cards, and the chance of drawing out two cards with the name Susan is low. The cards with Scott match up more quickly than the cards with Susan, because there are more copies with the name Scott. Similarly, in a renaturation reaction, if some sequences of DNA are present in multiple copies, they will renature more quickly.


When double-stranded DNA is heated, it denatures, separating into single-stranded molecules. On cooling, these single-stranded molecules pair and re-form double-stranded DNA, a process called renaturation. A C0t curve is a plot of a renaturation reaction.

Types of DNA Sequences in Eukaryotes

For most eukaryotic organisms, C0t curves similar to the one presented in FIGURE 11.15 are produced and indicate that eukaryotic DNA consists of at least three types of sequences. Slowly renaturing DNA consists of sequences that are present only once, or at most a few times, in the genome. This nonrepetitive, unique-sequence DNA includes sequences that code for proteins, as well as a great deal of DNA whose function is unknown. The more rapidly renaturing DNA represents two kinds of repetitive DNA—



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