In which of the following synthesis of DNA strand is not involved directly?

Options

A. m RNA
B. t RNA
C. Another DNA strand
D. Protein

Answer

To determine which of the following is not directly involved in the synthesis of a DNA strand, we need to analyze each option provided: mRNA, tRNA, another DNA strand, and protein.

1. **Understanding DNA Synthesis**:
- The process of synthesizing a new DNA strand from an existing DNA template is known as **replication**. During replication, the existing DNA strands serve as templates to create new complementary strands.

2. **Analyzing Each Option**:
- **mRNA (messenger RNA)**: This is synthesized from DNA during the process called **transcription**. While mRNA is derived from DNA, it is not involved in the direct synthesis of a DNA strand.
- **tRNA (transfer RNA)**: Similar to mRNA, tRNA is also synthesized from DNA during transcription. It plays a role in protein synthesis but does not directly contribute to DNA strand synthesis.
- **Another DNA strand**: This is directly involved in the synthesis of a new DNA strand during replication, as it serves as a template.
- **Protein**: Proteins are synthesized from mRNA through the process of **translation**. Proteins do not play a direct role in the synthesis of DNA strands.

3. **Conclusion**:
- Among the options, **protein** is the one that is not directly involved in the synthesis of a DNA strand. Therefore, the correct answer is **option 4 (protein)**.