Question

Calculate the length of the 50,000 - bpDNA in a 30 - nmfiber.

Short answer

The DNA in 30 - nm fibre has a length of 405 - nm .

Step-by-step solution

Calculation of contour length.

DNA coils around nucleosome residues during chromatin synthesis. By folding in a zigzag pattern, chromatin condenses even more to a 30 - nm diameter helical fibre.

The contour length must be calculated as follows:

$50,000-bp\times 3.4A=170,000A$

Determine the length of the DNA.

The initial coiling of the DNA around the histone cuts the length in half, and the creation of the 30 - nm fibre cuts the length in half again. As a result, the packing ratio of the 30 - nm fibre is as follows:$7\times 6=42$.

The DNA in 30 - nm fibre has the following length:

$\frac{170,000}{42}=4047A$which is equal to 405 - nm.