No. of hydrogen bonds present between G and C

Options

A. 2
B. 3
C. 1
D. 0

Answer

To determine the number of hydrogen bonds present between guanine (G) and cytosine (C), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structures of Guanine and Cytosine**:
- Guanine (G) has a specific structure that includes nitrogen (N) and oxygen (O) atoms.
- Cytosine (C) also has a structure that includes nitrogen (N) and oxygen (O) atoms.

2. **Draw the Structures**:
- Draw the chemical structure of guanine, noting the positions of the nitrogen and oxygen atoms.
- Draw the chemical structure of cytosine, similarly noting the positions of the nitrogen and oxygen atoms.

3. **Analyze Hydrogen Bonding Sites**:
- Look for potential hydrogen bonding sites in both structures.
- Guanine has an NH2 group and an NH group, which can participate in hydrogen bonding.
- Cytosine has an NH group and a carbonyl (C=O) group that can also participate in hydrogen bonding.

4. **Count the Hydrogen Bonds**:
- Guanine can form two hydrogen bonds with cytosine:
- One hydrogen bond is formed between the NH group of guanine and the carbonyl oxygen (C=O) of cytosine.
- The second hydrogen bond is formed between the NH group of cytosine and the NH2 group of guanine.

5. **Conclusion**:
- Therefore, the total number of hydrogen bonds formed between guanine and cytosine is **three**.

### Final Answer:
The number of hydrogen bonds present between G (guanine) and C (cytosine) is **three**.

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