Question

Nucleosomes are formed when DNA wraps __________ times around the histone octamer in a __________ coil.

a. 2.0; right-handed
b. 2.5; left-handed
c. 1.7; left-handed
d. 1.3; right-handed

Answer 1

DNA wraps 1.7 times around the histone octamer in a left-handed coil, forming the nucleosome complex involved in DNA packaging. The correct option is (c) 1.7; left-handed.

Step-by-step explanation:

Nucleosomes are critical for compacting the long eukaryotic DNA molecules into a space-efficient form within the cell nucleus. DNA wraps around a core of histone proteins to form the nucleosome complex, helping to organize and condense the DNA. The correct answer to the question is: DNA wraps 1.7 times around the histone octamer in a left-handed coil, making the correct option (c) 1.7; left-handed. This wraps the negatively charged DNA around the positively charged histone core, consisting of eight histone proteins (two copies each of H2A, H2B, H3, and H4), and allowing about 146 base pairs of DNA to loop around this octamer.