Question

The approximate size of a nucleus in a typical mammalian cell is about ______ meter and the length of DNA molecule is about ______ meters respectively.

• A. \(10^{-9}\) and 4.8
• B. \(10^{-6}\) and 3.8
• C. \(10^{-6}\) and 2.2
• D. \(10^{-2}\) and 1.2

Hint:

Multiply the number of base pairs in a diploid human cell by the distance between adjacent base pairs.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept
A typical mammalian nucleus is a few micrometres across, so its size is of the order of \(10^{-6}\) m.

Step 2: Calculation of DNA length
A diploid human cell has about \(6.6\times 10^{9}\) base pairs, and adjacent base pairs are \(0.34\) nm apart.

Step 3: Length
Length \(= 6.6\times 10^{9}\times 0.34\times 10^{-9}\) m \(\approx 2.2\) m.

Step 4: Result
So a DNA of about 2.2 m is packed inside a nucleus of about \(10^{-6}\) m, which needs histone based packaging.

Final Answer:
The nucleus is about 10^-6 m and the DNA is about 2.2 m long. \[ \boxed{\text{(C) }10^{-6}\text{ and }2.2} \]