Question

What is the significance of chromatin packaging?

• A. To accommodate long chromosome fibre and decrease length of its DNA for accommodation in nucleus
• B. To stabilize the gene
• C. To make DNA replication easy
• D. To make the process of transcription easy

Answer 1

The correct option is A To accommodate long chromosome fibre and decrease length of its DNA for accommodation in nucleus

Chromosomal DNA is packaged with assistance of histones which are positively-charged proteins and strongly adhere to negatively-charged DNA thereby, forming complexes known as nucleosomes. Each bead of nuclesome has 200 bp of DNA which is wound 1.65 times around histone octamer. Nucleosomes are coiled to form a 30-nanometer chromatin fiber, which forms 300 nm long loops. These 300 nm fibres are again folded to produce a 250 nm fibre that is tightly coiled into the chromatid of a chromosome. The whole event allow microscopic nucleus to accommodate a DNA as long as 2 meters having around 3 billion base pairs; correct option is A. The chromatin is unpacked during replication and transcription, which rule out the possibility of role of chromatin packaging in replication and transcription.

Thus, the correct answer is option A.