A) binding of histone proteins
B) binding of acidic proteins
C) binding of RNA molecules
D) binding of glycoproteins
Correct Answer: B
Solution :
Twin helical strands form the DNA backbone. Another double helix may be found tracing the spacer, or grooves, between the strands. These voids are adjacent to the base pairs and may provide a binding site. As the strands are not symmetrically located with respect to each other, the grooves are unequally sized. One groove, the major groove, is \[22\text{ }\overset{{}^\circ }{\mathop{A}}\,\] wide and the other the minor groove, is \[12\text{ }\overset{{}^\circ }{\mathop{A}}\,\] wide. The narrowness of the minor groove means that the edges of the bases are more accessible in the major groove. As a result, proteins like transcription factors that can bind to specific sequences in double-stranded DNA usually make contacts to the sides of the bases exposed in the major grooves. This situation varies in on usual conformations of DNA within the cell, but the major and minor grooves are always named to reflect the differences in size that would be seen if the DNA is twisted back into the ordinary B form.
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