Activator or repressor proteins which bind DNA to regulate the transcription of genes do so mainly by: A. Covalent interactions between the protein and specific bases in the major groove of DNA B. Covalent interactions of Zn2 atoms with the phosphodiester backbone C. Non-covalent interactions between the protein and specific bases in the major groove of DNA D. Covalent interactions with nearby nucleosomes E. Answers B and D are correct

C. Non-covalent interactions between the protein and specific bases in the major groove of DNA

Explanation:

Activator or repressor proteins are proteins with specific DNA-binding domains that have affinity by one or two DNA strands. In general, these proteins interact with the major groove of the B-DNA structure since this structure exposes more functional groups for binding. Non-covalent interactions are a type of interaction that does not involve the sharing of electrons. The interaction between proteins and DNA is due to the combination of different non-covalent interactions, which can be classified into four major types: van der Waals, hydrophobic, hydrogen and ionic interactions.

oxygen +1 most likely