Which one is correct base pairing for DNA molecule ?

Options

A. Cytosine-Uracil
B. Thymine - Guanine
C. Adenine - Thymine
D. Thymine - Uracil.

Answer

To determine the correct base pairing for a DNA molecule, we need to understand the structure of DNA and the rules of base pairing.

### Step-by-Step Solution:

1. **Identify the Components of DNA**:
- DNA is composed of nucleotides, which consist of a sugar (deoxyribose), a phosphate group, and a nitrogenous base.

2. **Know the Types of Nitrogenous Bases**:
- There are two categories of nitrogenous bases in DNA:
- **Purines**: Adenine (A) and Guanine (G)
- **Pyrimidines**: Thymine (T) and Cytosine (C)

3. **Understand Base Pairing Rules**:
- In DNA, the base pairing occurs as follows:
- Adenine (A) pairs with Thymine (T) through two hydrogen bonds.
- Guanine (G) pairs with Cytosine (C) through three hydrogen bonds.

4. **Identify the Correct Pairings**:
- The correct base pairs in DNA are:
- A-T (Adenine-Thymine)
- G-C (Guanine-Cytosine)

5. **Conclusion**:
- Therefore, the correct base pairing for a DNA molecule is:
- Adenine pairs with Thymine (A-T)
- Guanine pairs with Cytosine (G-C)

### Final Answer:
The correct base pairing for a DNA molecule is Adenine (A) with Thymine (T) and Guanine (G) with Cytosine (C).

---