Question

When double-stranded DNA is heated to 100°C, the two strands separate because the hydrogen bonds between the strands break. When the solution is cooled, the two strands can find each other to re-form the double helix, a process called renaturation or reannealing. For example, consider the following DNA double helix

5' - GCGCGCGCGCGCGC - 3'
3' - CGCGCGCGCGCGCG - 5'
Now, imagine that this DNA is heated to 100°C and then cooled, but the two separated strands never find each other. The local secondary structure of each single strand might assume the shape of a ___________ loop.

Answer 1

When DNA double-strands are heated to 100°C and not able to re-form after cooling, each single strand can assume the shape of a loop in its local secondary structure.

Step-by-step explanation:

When double-stranded DNA is heated to 100°C, the two strands separate because the hydrogen bonds between the strands break. When the solution is cooled, the two strands can find each other to re-form the double helix, a process called renaturation or reannealing. In the case where the two strands never find each other after being heated and cooled, each single strand can assume the shape of a loop in its local secondary structure.