Question

Read the following statements and choose the set of correct statements:

1. Euchromatin is loosely packed chromatin
2. Heterochromatin is transcriptionally active
3. Histone octamer is wrapped by negatively charged DNA in nucleosome
4. Histones are rich in lysine and arginine
5. A typical nucleosome contains 400 bp of DNA helix

Choose the correct answer from the options given below:

• A. (b), (d), (e) Only
• B. (a), (c), (d) Only
• C. (b), (e) Only
• D. (a), (c), (e) Only

Answer 1

The Correct Option is B

To determine the correct set of statements, we must evaluate each statement's accuracy based on knowledge of chromatin structure and composition:

1. Euchromatin is loosely packed chromatin: This statement is correct. Euchromatin is the less condensed form of chromatin, allowing for transcriptional activities due to its loose packing.
2. Heterochromatin is transcriptionally active: This statement is incorrect. Heterochromatin is tightly packed and generally transcriptionally inactive.
3. Histone octamer is wrapped by negatively charged DNA in nucleosome: This statement is correct. DNA, which is negatively charged, wraps around a histone octamer to form a nucleosome.
4. Histones are rich in lysine and arginine: This statement is correct. Histones contain high amounts of the positively charged amino acids lysine and arginine, facilitating their interaction with the negatively charged DNA.
5. A typical nucleosome contains 400 bp of DNA helix: This statement is incorrect. A typical nucleosome contains approximately 147 base pairs of DNA wrapped around the histone core.

Evaluating these statements, the correct combination of statements is (a), (c), and (d) only.