Anucleosome forms hydrogen bonds with what part of the dna?
a) only with bases via the minor groove
b) with the phosphodiester backbone and with bases via the major groove
c) only with bases via the major groove
d) with the phosphodiester backbone and with bases via the minor groove

D) with the phosphodiester backbone and with bases via the minor groove

Explanation:

The double helix is a fairly rigid and viscous molecule of immense length and a small diameter. In this molecule a major groove and a minor groove can be observed.

The major groove is deep and wide, the minor groove is shallow and narrow.

DNA-protein interactions are essential processes in cell life (activation or repression of transcription, DNA replication and repair).

Proteins bind to the inner part of the DNA grooves, through specific junctions: hydrogen bonds, and non-specific junctions: van der Waals interactions, and other general electrostatic interactions.

The proteins recognize donors and acceptors of hydrogen bonds, methyl groups (hydrophobic), the latter exclusive of the major groove; There are four possible patterns of recognition in the major groove, and only two in the minor groove (see figures).

Some proteins bind to DNA through the major groove, some others through the minor groove, and some need to bind to both, but the nucleosome form hydrogen bonds via the minor groove with the phophodiester backbone.

c is the correct answer!