The association of histone H1 with a nucleosome indicates:
1. DNA replication is occurring
2. The DNA is condensed into a chromatin fibre
3. The DNA double helix is exposed
4. Transcription is occurring
With respect to nucleosome, which of the following statements is incorrect ?
| 1. | Nucleosome contains 120 bp of DNA helix. |
| 2. | Nucleosomes are seen as 'beads' on string' under Electron Microscope. |
| 3. | DNA is wrapped around positively charged histone octamer to form nucleosome. |
| 4. | Nucleosome is the repeating unit of chromatin. |
| (a) | Euchromatin is loosely packed chromatin. |
| (b) | Heterochromatin is transcriptionally active. |
| (c) | Histone octomer is wrapped by negatively charged DNA in nucleosome. |
| (d) | Histones are rich in lysine and arginine. |
| (e) | A typical nucleosome contains 400 bp of DNA helix. |
| 1. | (a), (c), (e) only | 2. | (b), (d), (e) only |
| 3. | (a), (c), (d) only | 4. | (b), (e) only |
| Assertion (A): | Euchromatin is said to be transcriptionally inactive chromatin. |
| Reason (R): | In a typical nucleus, euchromatin is the region of chromatin that is loosely packed and stains light. |
| 1. | Both (A) and (R) are True but (R) does not correctly explain (A). |
| 2. | (A) is False but (R) is True. |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are True and (R) correctly explains (A). |