What is the structure formed when DNA is coiled around bundles of eight to nine histone proteins?

What is the structure formed when DNA is coiled around bundles of eight to nine histone proteins?

• A. Nucleosome
• B. Chromatid
• C. Chromosome
• D. Beads on a String

Answer: (A)

DNA packaging into chromatin starts with nucleosomes, the basic repeating unit where DNA wraps around a histone core. A nucleosome forms when about 146 base pairs of DNA coil around an octamer of histone proteins (two each of H2A, H2B, H3, and H4). This wrapping creates one “bead” in the beads-on-a-string appearance, and a linker histone H1 helps stabilize and compact the structure further into higher-order fibers. The other terms describe different levels of chromatin or condensed chromosomes, not the basic unit formed by DNA wrapping around histones. So the structure formed when DNA is coiled around bundles of eight histone proteins is a nucleosome.

DNA packaging into chromatin starts with nucleosomes, the basic repeating unit where DNA wraps around a histone core. A nucleosome forms when about 146 base pairs of DNA coil around an octamer of histone proteins (two each of H2A, H2B, H3, and H4). This wrapping creates one “bead” in the beads-on-a-string appearance, and a linker histone H1 helps stabilize and compact the structure further into higher-order fibers. The other terms describe different levels of chromatin or condensed chromosomes, not the basic unit formed by DNA wrapping around histones. So the structure formed when DNA is coiled around bundles of eight histone proteins is a nucleosome.