Which type has DNA tightly wrapped around histone proteins?

• A. Eukaryotic
• B. Prokaryotic
• C. Both
• D. Neither

Answer: (A)

In eukaryotes, DNA is wrapped around histone proteins to form nucleosomes. This arrangement compactly organizes long DNA molecules inside the nucleus and provides a way to regulate access for transcription, replication, and repair. The core histone octamer (two copies each of H2A, H2B, H3, and H4) serves as the spool, around which about 146 base pairs of DNA wind, with a linker histone H1 helping pack nucleosomes into higher-order fibers.

Prokaryotes, on the other hand, do not use this histone-based packaging. Their DNA is typically supercoiled and organized by other DNA-binding proteins rather than being wrapped around histones. Some archaea have histone-like proteins, but the classic tightly wrapped nucleosome structure is a feature of eukaryotes.

So, the type that has DNA tightly wrapped around histone proteins is eukaryotic.