Question

Which is the correct order of progressively higher levels of chromatin organization?
A. Nucleosome
B. 30 nm chromatin fibre
C. Looped domain

• A. A $\rightarrow$ B $\rightarrow$ C
• B. C $\rightarrow$ B $\rightarrow$ A
• C. C $\rightarrow$ A $\rightarrow$ B
• D. A $\rightarrow$ C $\rightarrow$ B

Hint:

Remember the order: Beads on a string (Nucleosome) $\rightarrow$ Fiber $\rightarrow$ Loops.

Answer 1

The Correct Option is A

Step 1: Concept
Chromatin organization involves the hierarchical folding of DNA to fit within the nucleus.

Step 2: Meaning
Progressively higher levels refer to the transition from simple DNA-protein complexes to more complex folded structures.

Step 3: Analysis
The first level of organization is the nucleosome (A), where DNA wraps around histone octamers. These nucleosomes then coil into a 30 nm chromatin fibre (B). Finally, these fibres fold into looped domains (C) attached to a nuclear scaffold.

Step 4: Conclusion
The correct sequence from simplest to most complex is Nucleosome $\rightarrow$ 30 nm fibre $\rightarrow$ Looped domain. Final Answer: (A)