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DNA associates very tightly with nucleosomes because?
a. DNA can form covalent bonds with histone proteins.
b. negative charges on DNA are attracted to positive charges of the histone proteins.
c. the histone tails wrap tightly around the DNA double helix.
d. the amino acids of histone proteins are largely acidic, while DNA molecules are basic.
e. histone H1 tightens the coils of DNA that are wrapped around the nucleosome.
2 Answers
- C.W.G.KLv 41 decade agoFavorite Answer
DNA has a slightly negative charge due to the phosphates found in the sugar-phosphate backbone. Histone proteins, however, are positively charged*. Consequently, DNA tightly wraps around the histone core. The answer you want is B.
*Generally, histone proteins are positively charged. They can become neutrally charged, however, due to the action of enzymes called Histone Deacetylases (or HDACs). These enzymes remove acetyl groups from lysine residues in the histone proteins, neutralizing the positive charge. DNA no longer tightly associates with the histone core and is now readily accessible for transcription or replication. Conversely, histones can become positively charged again through the action of Histone Acetyltransferases (or HATs), which add the acetyl groups back.
