Question

Chromatin material which remains condensed during interphase is called
(a) Heterochromatin
(b) Euchromatin
(c) Chromonemata
(d) Megachromatin

Answer 1

Hint: Chromatin is the condensed form of DNA. DNA is condensed by wrapping itself around histone proteins. Normally the DNA is loosely wrapped but just before cell division, it coils itself to form chromatin which further coils to form structures known as chromosomes.

Complete Step by Step Answer:
Interphase is referred to as that phase of the cell cycle in which cell division does not take place. In interphase, the cell grows in size i.e. G1 phase, synthesis, or doubles it DNA content i.e. S phase, and prepares itself for cell division i.e. G2 phase. During interphase, the cell is metabolically active and thus the DNA is in loose form to allow transcription and translation. This part of DNA that is not condensed during interphase is known as Euchromatin.
But there is also part of DNA that does not open or remains condensed during interphase and is known as Heterochromatin. It remains condensed because it does not have any genes. Hence, it does not need to take part in transcription and translation.
So, the correct option is ‘Heterochromatin’.

Additional information: Heterochromatin and euchromatin are classified on the basis of how they appear under a microscope.
Euchromatin: It stains lightly and has a transcriptionally active part of DNA.
Heterochromatin: It gets highly stained because of the dense DNA present in it. Also because it has high ribonucleic acid content. It has a high number of tandem repeats in it as well.

Note:
- Chromatin is made up of a repeating unit known as nucleosomes.
- Nucleosomes are made up by coiling a negatively charged DNA around an octamer of positively charged histone proteins.
- Each nucleosome is made up of 200 base pairs of DNA.