Which one is a nucleotide ?

Options

A. Adenylic acid and guanosine mono- phosphate
B. Cytidylic acid and uridine
C. Uridylic acid and cytosine
D. All of the above

Answer

To determine which of the given options is a nucleotide, we first need to understand what a nucleotide is and its components.

### Step-by-Step Solution:

1. **Definition of a Nucleotide**:
A nucleotide is an organic molecule that serves as the building block of nucleic acids, such as DNA and RNA. It consists of three main components:
- A phosphate group
- A five-carbon sugar (ribose in RNA and deoxyribose in DNA)
- A nitrogenous base (which can be adenine, guanine, cytosine, thymine, or uracil)

2. **Analyzing the Options**:
We need to evaluate each option provided to see if it meets the criteria of a nucleotide.

- **Option 1: Adenylic Acid and Guanosine Monophosphate**
- **Adenylic Acid**: This consists of an adenosine molecule (which is a nitrogenous base) bonded to one phosphate group and a ribose sugar. Thus, it has all three components of a nucleotide.
- **Guanosine Monophosphate (GMP)**: This is also a nucleotide, consisting of guanosine (a nitrogenous base), a phosphate group, and a ribose sugar. Therefore, both adenylic acid and guanosine monophosphate are nucleotides.

- **Option 2: Cytidilic Acid and Uridine**
- **Cytidilic Acid**: This is a nucleotide composed of cytidine (a nitrogenous base), a phosphate group, and a ribose sugar. Thus, it is a nucleotide.
- **Uridine**: This is a nucleoside, which means it contains a nitrogenous base (uracil) and a sugar but lacks a phosphate group. Therefore, uridine is not a nucleotide.

- **Option 3: Uridylic Acid and Cytosine**
- **Uridylic Acid**: This is a nucleotide composed of uridine (a nitrogenous base), a phosphate group, and a ribose sugar. Thus, it is a nucleotide.
- **Cytosine**: This is a nitrogenous base and not a nucleotide.

- **Option 4: All of the Above**: Since not all options consist of nucleotides (as explained above), this option is incorrect.

3. **Conclusion**:
The correct answer is **Option 1: Adenylic Acid and Guanosine Monophosphate**, as both are nucleotides.