Question

histone proteins have many lysines and arginines in their primary sequences. these amino acids carry full positive charges. each phosphate group in dnas sugar-phosphate backbone carries a full negative charge. which of the following is the correct connection between these observations? choose the single best answer.

the histones and dna in a nucleosome stick together via covalent bonding.

the histones and dna in a nucleosome stick together via electrical (+/-) interactions.

the lysines and arginines in the histones attract each other, forming the ball-like structure.

Explanation:

• Covalent bonding involves sharing of electrons. Here, the interaction is due to charges (positive from lysines/arginines in histones and negative from phosphate groups in DNA), not electron - sharing.
• Electrical (+/-) interactions occur between oppositely charged species. Histones have positively charged amino acids (lysines and arginines) and DNA has negatively charged phosphate groups. Opposite charges attract each other.
• Lysines and arginines in histones are positively charged. Like charges repel each other, so they cannot attract each other to form a ball - like structure.

Answer:

The histones and DNA in a nucleosome stick together via electrical (+/-) interactions.