The function of nucleases is to:

Options

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

Answer

**Step-by-Step Solution:**

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

2. **Identifying the Bonds**: The primary function of nucleases is to break the phosphodiester bonds. These bonds link the nucleotides together in a polynucleotide chain (DNA or RNA).

3. **Fragmentation of DNA**: When nucleases act on nucleic acids, they cleave the phosphodiester bonds, leading to the fragmentation of the DNA or RNA molecule. This is essential for various biological processes, including DNA repair, replication, and degradation.

4. **Evaluating Options**:
- The first option mentions breaking the polynucleotide chain by targeting terminal nucleotides, which is not the primary action of nucleases.
- The second option correctly states that nucleases break the phosphodiester bonds, leading to the fragmentation of the nucleic acid.
- The third option discusses peptide bonds, which are not related to nucleases but to proteases.
- The fourth option mentions ester bonds, which are broken down by lipases, not nucleases.

5. **Conclusion**: Based on the analysis, the correct function of nucleases is to break the phosphodiester bonds, resulting in the fragmentation of nucleic acids.

**Final Answer**: The function of nucleases is to break the phosphodiester bonds in nucleic acids, leading to their fragmentation.

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