RNA primer is required for

Options

A. transcription or synthesis of RNA over DNA
B. translation or polypeptide synthesis with RNA help
C. DNA repair
D. DNAreplication

Answer

To answer the question "RNA primer is required for," we need to understand the role of RNA primers in the context of DNA replication. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding DNA Structure**:
- DNA is a double helical structure composed of two strands that run in opposite directions (antiparallel).
- Each strand has a 5' (five prime) end and a 3' (three prime) end.

**Hint**: Recall that DNA strands are antiparallel, meaning one runs from 5' to 3' and the other from 3' to 5'.

2. **DNA Replication Process**:
- During DNA replication, the double helix unwinds, creating a replication fork where the two strands separate.
- DNA polymerase is the enzyme responsible for synthesizing new DNA strands.

**Hint**: Remember that the replication fork is where the DNA strands are separated for replication.

3. **Direction of DNA Polymerase Activity**:
- DNA polymerase can only add nucleotides in the 5' to 3' direction.
- This means it reads the template strand from 3' to 5'.

**Hint**: Focus on the directionality of DNA synthesis and how it affects the replication process.

4. **Need for RNA Primer**:
- For DNA polymerase to start synthesizing a new strand, it requires a free 3' hydroxyl (OH) group.
- The RNA primer provides this 3' OH group, allowing DNA polymerase to initiate replication.

**Hint**: Consider why DNA polymerase cannot start a new strand without an existing 3' end.

5. **Leading and Lagging Strands**:
- The leading strand is synthesized continuously in the direction of the replication fork.
- The lagging strand is synthesized in short segments called Okazaki fragments, which are initiated by RNA primers.

**Hint**: Distinguish between the leading and lagging strands based on how they are synthesized.

6. **Conclusion**:
- Therefore, the RNA primer is essential for DNA replication as it provides the necessary starting point for DNA polymerase to synthesize new DNA strands.

**Hint**: Summarize the role of RNA primers in the context of DNA replication to solidify your understanding.

### Final Answer:
RNA primer is required for **DNA replication**.