Function of Nucleases :

Options

A. Break the polynucleotide chain by breaking the each terminal nucleotide
B. Breaks phosphodiester bond
C. Breaks peptide bonds
D. Breaks ester bonds

Answer

### Step-by-Step Solution:

1. **Understanding Nucleases**: Nucleases are enzymes that play a crucial role in the metabolism of nucleic acids (DNA and RNA). They are responsible for breaking down nucleic acids into smaller components.

2. **Identifying Nucleic Acids**: Nucleic acids, such as DNA and RNA, are made up of units called nucleotides. Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.

3. **Types of Bonds in Nucleic Acids**: The nucleotides in nucleic acids are connected by covalent bonds known as phosphodiester bonds. These bonds form between the 5' carbon of one nucleotide's sugar and the 3' carbon of the next nucleotide's sugar.

4. **Function of Nucleases**: The primary function of nucleases is to cleave these phosphodiester bonds. This action can lead to the breakdown of the nucleic acid chain, which is essential for various biological processes, including DNA replication and repair.

5. **Types of Nucleases**: There are two main types of nucleases:
- **Exonucleases**: These enzymes remove nucleotides from the ends of the nucleic acid chain.
- **Endonucleases**: These enzymes cut the nucleic acid chain at internal sites, breaking the phosphodiester bonds within the chain.

6. **Evaluating the Options**:
- **Break the polynucleotide chain by breaking each terminal nucleotide**: This is incorrect as only exonucleases can do this.
- **Breaks phosphodiester bond**: This is correct as it describes the primary function of nucleases.
- **Breaks peptide bonds**: This is incorrect as peptide bonds are found in proteins, not nucleic acids.
- **Breaks ester bonds**: This is also incorrect as ester bonds are not the primary focus of nucleases.

7. **Conclusion**: The correct answer is that nucleases break phosphodiester bonds.