Which of the following enzymes are used to join bits of DNA

Options

A. Ligase
B. Primase
C. DNA polymerase
D. Endonuclease

Answer

To answer the question "Which of the following enzymes are used to join bits of DNA?", we will analyze each of the given enzymes:

1. **Ligase**: This enzyme is often referred to as "molecular glue" because it plays a crucial role in the process of ligation, which is the joining of DNA fragments together. Ligase facilitates the formation of phosphodiester bonds between adjacent nucleotides, effectively sealing gaps in the DNA backbone. Therefore, ligase is the enzyme that is specifically used to join bits of DNA.

2. **Primase**: This enzyme synthesizes short RNA primers that are necessary for DNA replication. Primase does not join DNA fragments; instead, it provides a starting point for DNA polymerase to begin synthesis.

3. **DNA Polymerase**: This enzyme is responsible for synthesizing new DNA strands by adding nucleotides to a growing DNA chain. While it plays a critical role in DNA replication and amplification, it does not join DNA fragments together.

4. **Endonuclease**: This enzyme cuts the DNA at specific internal sites within the DNA strand. It does not join DNA fragments; rather, it breaks the DNA chain.

Based on the analysis, the correct answer to the question is **Ligase**, as it is the enzyme specifically responsible for joining bits of DNA together.

### Summary of Steps:
1. Identify the enzymes listed in the question.
2. Analyze the function of each enzyme:
- Ligase: Joins DNA fragments.
- Primase: Synthesizes RNA primers.
- DNA Polymerase: Synthesizes new DNA strands.
- Endonuclease: Cuts DNA at internal sites.
3. Conclude that Ligase is the enzyme that joins bits of DNA.