DNA Structure and Replication

ID #1684

Given the hypothetical GC content of the organisms listed below, determine which source of DNA would denature at the lowest temperature. Incorrect: Neurospora crassa 100% Incorrect: Pseudomonas aeruginosa 46% Correct: Rat- 5% Incorrect: Baker's Yeast 94% Incorrect: Escherichia coli 92% Why is it so?

The key to understanding this question is knowing the significance of increased GC content in an organism's DNA. The more GC base pairs there are, the more hydrogen bonds there are holding the strands together, which means the more heat will be necessary to separate the strands. So the organism with the lowest GC content will be the one whose DNA will separate the easiest and denature at the lowest temperature. In your particular version of the question, that would be the 5% instead of the higher percentages.

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