Number of hydrogen bond formed between adenine and thymine to connect each other is/are ______

2

The correct answer is option 2. 2.

In DNA, the nitrogenous bases form pairs through hydrogen bonding, which is crucial for the stability of the DNA double helix. These base pairs follow specific rules known as complementary base pairing:

Adenine (A) pairs with Thymine (T) in DNA.

Guanine (G) pairs with Cytosine (C).

Let us focus on the adenine (A) and thymine (T) pair.

Structure of Adenine and Thymine:

Adenine is a purine base, which consists of a double-ring structure.

Thymine is a pyrimidine base, which has a single-ring structure.

Hydrogen Bonding Between Adenine and Thymine:

Hydrogen bonds form between specific atoms in adenine and thymine, where partially positive hydrogen atoms interact with electronegative atoms such as nitrogen or oxygen. The number of hydrogen bonds between adenine and thymine is two, and they occur as follows

First hydrogen bond:

The NH group (donor) of adenine (attached to the 6th carbon atom in adenine’s ring) forms a hydrogen bond with the carbonyl oxygen (C=O) (acceptor) at the 4th carbon atom of thymine.

Second hydrogen bond:

The NH group (donor) of thymine (attached to the 3rd carbon atom in thymine’s ring) forms a hydrogen bond with the nitrogen atom (N) at the 1st position in adenine (acceptor).

Visualization of the Hydrogen Bonds:

The interaction involves one oxygen atom and one nitrogen atom from thymine, forming hydrogen bonds with two hydrogen atoms on adenine.

Summary of Hydrogen Bond Formation:

Adenine and thymine form two hydrogen bonds to pair with each other in the DNA structure.

These hydrogen bonds stabilize the double helix and contribute to the specific pairing between purine (adenine) and pyrimidine (thymine) bases.

The reason only two hydrogen bonds are formed between adenine and thymine (compared to three hydrogen bonds between guanine and cytosine) is due to the specific positioning of hydrogen donors and acceptors on the adenine and thymine molecules.

Conclusion:

The number of hydrogen bonds between adenine and thymine in DNA is 2. This specific pairing ensures the stability and correct structure of the DNA double helix.

Thus, the correct answer is: 2. 2.