Question

Select the INCORRECT statement.

• A. DNA is negatively charged molecule.
• B. Histone proteins are rich in lysine and arginine residues.
• C. The chromatin packed to form solenoid structure looks like 'beads-on-string'
• D. Non-histone chromosomal proteins are required for packaging of chromatin at higher levels.

Hint:

Structure memory: Nucleosome = beads-on-string; Solenoid = coiled fiber.

Answer 1

The Correct Option is C

Concept:
DNA packaging in eukaryotes involves multiple levels of organization from nucleosomes to higher-order structures.

Step 1: Understand basic facts.
• DNA is negatively charged due to phosphate groups \checkmark
• Histones are rich in basic amino acids (lysine and arginine) \checkmark

Step 2: Understand chromatin structure.
• Nucleosome structure → Appears as beads-on-string
• Solenoid structure → Higher-order coiling of nucleosomes (30 nm fiber), not beads-on-string Thus, statement (C) is incorrect.

Step 3: Role of non-histone proteins. They help in higher-level packaging and organization of chromatin \checkmark

Step 4: Conclusion. \[ \text{Incorrect statement = Solenoid structure looks like beads-on-string} \]