General Biology

Question

you want to discover how much a heat a DNA strand can withstand before denaturing. Youdecide to heat DNA in a beaker and measure the amount of DNA content throughout. At the beginning the DNA begins to break down and find fragments of strands with both A-T and GC content. Towards the end of the experiment you measure the content again, what do you expect to find if you are expected to find some sort of DNA fragments?

Answer 1

I believe this question is trying to address the structure of DNA as it pertains to the bond strength between the various nucleotides, specifically A-T and G-C. Guanine (G) and Cytosine (C) form a bond consisting of three hydrogen bonds, whereas the pairing between adenine (A) and thymine (T) consists of only two hydrogen bonds. Therefore, the bond between G-C is stronger than A-T and more resistant to denaturation. In the case of the experiment outlined in your question, we would expect more fragments of DNA in the beaker that have not denatured to be those with a higher G-C content as more G-C conveys a stronger overall bond between the two DNA strands. In contrast, we would expect more denatured fragments that have a higher A-T content since those bonds are weaker.