Question

DNA in a 1 cm long chromatin contains \(5 \times 10^{9}\) base pairs. The fold compaction of this DNA within the chromatin is _______ (in integer).

Hint:

For DNA compaction problems: multiply base pairs by 0.34 nm to get contour length, then divide by observed chromatin length to get fold compaction.

Answer 1

Step 1: Length of B-DNA per base pair. 
Each base pair in B-DNA = 0.34 nm. 
Step 2: Total contour length of DNA. 
\[ L = (5 \times 10^9) \times 0.34 \times 10^{-9}\ \text{m} = 1.7\ \text{m}. \] Step 3: Length of chromatin. 
Given = 1 cm = 0.01 m. 
Step 4: Fold compaction. 
\[ \text{Fold compaction} = \frac{1.7}{0.01} = 170. \]