Which pairing is found in DNA?

Options

A. Adenine with thymine
B. Thymine with guanine
C. Guanine with adenine
D. Uracil with adenine

Answer

To answer the question "Which pairing is found in DNA?", we can follow these steps:

### Step 1: Identify the Nitrogenous Bases in DNA
DNA contains four nitrogenous bases:
- **Purines**: Adenine (A) and Guanine (G)
- **Pyrimidines**: Cytosine (C) and Thymine (T)

### Step 2: Understand Base Pairing Rules
According to Chargaff's rules, in DNA:
- Adenine (A) pairs with Thymine (T) through two hydrogen bonds.
- Cytosine (C) pairs with Guanine (G) through three hydrogen bonds.

### Step 3: List the Pairings
The pairings found in DNA are:
- Adenine (A) with Thymine (T)
- Cytosine (C) with Guanine (G)

### Step 4: Eliminate Incorrect Options
- Uracil (U) is not found in DNA; it is found in RNA.
- Pairing of two purines (A with G) or two pyrimidines (C with T) is incorrect as per Chargaff's rules.

### Conclusion
The correct pairings found in DNA are:
1. Adenine (A) with Thymine (T)
2. Cytosine (C) with Guanine (G)

Thus, the answer to the question is that the pairings found in DNA are A-T and C-G.

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