Question

Bent DNA: A. occurs only in the presence of external agents like the antitumor drugs. B. may be a fundamental element in the interaction between DNA sequences and proteins. C. occurs primarily in the presence of triple-stranded DNA. D. requires the presence of inverted repeats. E. occurs only in DNA that is in the Z form.

Short answer

Answer: Bent DNA may be a fundamental element in the interaction between DNA sequences and proteins.

Step-by-step solution

Understanding Bent DNA

Bent DNA refers to DNA with an altered or modified structure, usually involving a change in the normal helical conformation. These structural changes can be caused by various factors such as protein binding, inverted repeats or superhelical tension. The altered structure of bent DNA can play a crucial role in various biological processes, such as gene regulation, DNA replication, and DNA repair.

Evaluating Statement A

"occurs only in the presence of external agents like the antitumor drugs." This statement is not true. Bent DNA can occur naturally due to various factors like the presence of certain proteins or inverted repeats, not just due to external agents, such as antitumor drugs.

Evaluating Statement B

"may be a fundamental element in the interaction between DNA sequences and proteins." This statement is true. Bent DNA can significantly affect the interaction between DNA sequences and proteins, as the altered structure can create new recognition sites for the binding of proteins. These interactions can play a critical role in biological processes mentioned above.

Evaluating Statement C

"occurs primarily in the presence of triple-stranded DNA." This statement is not true. Bent DNA is not specifically associated with triple-stranded DNA. It can occur in both double-stranded and triple-stranded DNA due to various factors mentioned earlier.

Evaluating Statement D

"requires the presence of inverted repeats." This statement is not true. Although the presence of inverted repeats can contribute to bent DNA formation, it is not an essential requirement. There are other factors, such as protein binding, that can also cause bent DNA.

Evaluating Statement E

"occurs only in DNA that is in the Z form." This statement is not true. Bent DNA can occur in both B and Z form DNA structures. The association of bent DNA with Z form DNA is due to the fact that Z form DNA can exhibit a higher degree of bending compared to B form DNA; however, bent DNA is not exclusive to the Z form.

Selecting the Correct Statement

As we have gone through each statement and found only statement B to be true, the correct answer is: B. may be a fundamental element in the interaction between DNA sequences and proteins.