How are chromosomes formed from chromatin?
GeneralClass 12AllAnswered 27 Mar 2026
Answer
Chromatin condensation process:
- Interphase chromatin: Extended, loosely packed
- Composition: DNA + histone proteins (H1, H2A, H2B, H3, H4) + non-histone proteins + RNA
- Nucleosome formation: DNA (147 bp) wraps around histone octamer (2 copies each of H2A, H2B, H3, H4)
- "Beads-on-string" structure (10 nm fiber)
- Higher-order packing:
- Solenoid structure (30 nm fiber): Nucleosomes coil with H1 histone
- Looped domains: 30 nm fiber forms loops (300 nm fiber)
- Condensed chromatin: Further coiling during prophase
- Metaphase chromosome: Maximum condensation
- Coiling and supercoiling of chromatin
- 1400-fold compaction from extended DNA
- Visible as distinct, rod-shaped structures
Proteins involved: Condensins, topoisomerases, cohesin
Suggested Q&A
General · Class 12- GeneralClass 12Electric Field at Centre of Ring with Non-Uniform Charge Distribution. Four quadrants carry linear charge densities: +2λ, −2λ, +λ, −λ. Find electric field at centre.
- GeneralClass 12P°(hexane) = 408 Torr, P°(heptane) = 141 Torr. x(hexane) = 0.300. Find Y₆ and Y₇.
- GeneralClass 122N₂O₅(g) → 4NO₂(g) + O₂(g). Initial P = 50 mmHg; P at 30 min = 87.5 mmHg. Find P at 60 min.
- GeneralClass 12What is the difference between psychosis and neurosis?
- GeneralClass 12What is the difference between prism and a pyramid?
- GeneralClass 12What is the difference between phrase and clause?