What is the most likely reason for the conserved region of a promoter nearest the initiation point to have mostly adenines and thymines in its sequence?
A. RNA polymerases are better at incorporating uracils and thymines into RNA molecules than incorporating guanines and cytosines.
B. This is the region for separating template and non-template strands, and A-T base pairs are easier to separate than G-C base pairs.
C. Accessory proteins like sigma factors or transcription factors bind more easily to AT- rich sequences than they do to GC-rich sequences.
D. It is possible to create more unique sequences for recognition with adenines and thymines than it is with guanines and cytosines.
E. None of the above are likely reasons for the conserved region of a promoter nearest the initiation point having mostly adenines and thymines in its sequence.
Answer: B
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