The association of histone H1 with a nucleosome indicates :
- DNA replication is occurring
- Transcription is occurring
- The DNA is condensed into a Chromatin Fibre
- The DNA double helix is exposed
Answer
(3) The DNA is condensed into a Chromatin Fibre
Solution
A nucleosome = histone octamer (2 each of H2A, H2B, H3, H4) wrapped by about 200 bp of DNA.
⇒ Histone H1 binds the linker DNA where DNA enters and leaves the nucleosome and helps in coiling nucleosomes into the 30 nm chromatin fibre.
⇒ Such condensed DNA is not accessible for replication or transcription.
∴ Association of H1 indicates that DNA is condensed into a chromatin fibre.
Answer: (3)