Question

The total number of hydrogen bonds of a DNA-double Helix strand whose one strand has the following sequence of bases is _______ . $5^{\prime}-\mathrm{G}-\mathrm{G}-\mathrm{C}-\mathrm{A}-\mathrm{A}-\mathrm{A}-\mathrm{T}-\mathrm{C}-\mathrm{G}-\mathrm{G}-\mathrm{C}-\mathrm{T}-\mathrm{A}-3^{\prime}$

Hint:

Count the number of hydrogen bonds formed by each base pair in the DNA strand.

Answer 1

Correct Answer: 33

To calculate the total hydrogen bonds in a DNA double helix from a given sequence, the following base pairing rules and their associated hydrogen bonds are applied: Guanine (G) pairs with Cytosine (C) via 3 hydrogen bonds, and Adenine (A) pairs with Thymine (T) via 2 hydrogen bonds.
The sequence provided is:
5′-G-G-C-A-A-A-T-C-G-G-C-T-A-3′
The hydrogen bonds for each base pair are enumerated as follows:

• G-G: Two Guanine bases paired with Cytosine contribute 2 × 3 = 6 bonds.
• C: One Cytosine base paired with Guanine contributes 3 bonds.
• A-A-A: Three Adenine bases paired with Thymine contribute 3 × 2 = 6 bonds.
• T: One Thymine base paired with Adenine contributes 2 bonds.
• C: One Cytosine base paired with Guanine contributes 3 bonds.
• G-G: Two Guanine bases paired with Cytosine contribute 2 × 3 = 6 bonds.
• C: One Cytosine base paired with Guanine contributes 3 bonds.
• T: One Thymine base paired with Adenine contributes 2 bonds.
• A: One Adenine base paired with Thymine contributes 2 bonds.

The sum of these contributions yields the total number of hydrogen bonds: 6 + 3 + 6 + 2 + 3 + 6 + 3 + 2 + 2 = 33.
Therefore, the total number of hydrogen bonds is 33, falling within the specified range (33,33).