DNA strand is synthesized in the direction

Options

A. (a) `5' to 3'`
B. (b) `3' to 5'`
C. (c) `1' to 4'`
D. (d) `6' to 1'`

Answer

To answer the question about the direction in which DNA strands are synthesized, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the direction in which DNA strands are synthesized.

2. **Identify the Options**: The options provided are:
- A) 5 prime to 3 prime
- B) 3 prime to 5 prime
- C) 1 prime to 4 prime
- D) 6 prime to 1 prime

3. **Eliminate Incorrect Options**:
- Options C (1 prime to 4 prime) and D (6 prime to 1 prime) are not valid directions for DNA synthesis. DNA synthesis does not occur in these directions.

4. **Focus on the Remaining Options**: We are left with:
- A) 5 prime to 3 prime
- B) 3 prime to 5 prime

5. **Understand DNA Synthesis Mechanism**: DNA synthesis is facilitated by the enzyme DNA-dependent DNA polymerase. This enzyme catalyzes the addition of nucleotides to the growing DNA strand.

6. **Determine the Direction of Synthesis**:
- DNA polymerase adds nucleotides to the 3' end of the growing strand, meaning that the synthesis occurs in the 5' to 3' direction. This means that the strand starts at the 5' end and grows towards the 3' end.

7. **Select the Correct Answer**: Based on the understanding that DNA synthesis occurs in the 5' to 3' direction, the correct answer is:
- A) 5 prime to 3 prime.

### Final Answer:
The DNA strand is synthesized in the direction **5 prime to 3 prime**.

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