Question

Process of DNA replication involves
• DNA polymerase synthesis
• Semi conservative
• In eukaryotes occur in cytoplasm
• Require RNA primer Choose the correct answer from the options given below:

• A. A & B Only
• B. A, B & C Only
• C. B, C & D Only
• D. A, B & D Only

Hint:

DNA polymerase cannot initiate DNA synthesis on its own. It always requires an RNA primer.

Answer 1

The Correct Option is D

Concept: DNA replication is the biological process by which a cell produces an identical copy of its DNA before cell division. Important features of DNA replication:
• It is semi-conservative.
• DNA polymerase enzyme synthesizes DNA.
• RNA primers are required for initiation.
• In eukaryotes, replication occurs inside the nucleus.

Step 1: Analyze statement A: DNA polymerase synthesis. DNA polymerase is the major enzyme responsible for:
• Adding nucleotides to growing DNA strand.
• Synthesizing complementary DNA strand. Thus statement A is correct.

Step 2: Analyze statement B: Semi-conservative replication. DNA replication follows: \[ \boxed{ \text{Semi-conservative mode} } \] Meaning:
• Each newly formed DNA molecule contains:
• One parental strand
• One newly synthesized strand This was experimentally proved by: \[ \boxed{ \text{Meselson and Stahl experiment} } \] Hence statement B is correct.

Step 3: Analyze statement C carefully. Statement C says: \[ \text{In eukaryotes occur in cytoplasm} \] This is incorrect because:
• Eukaryotic DNA replication occurs in the nucleus.
• Cytoplasmic replication mainly occurs in prokaryotes due to absence of nucleus. Thus statement C is false.

Step 4: Analyze statement D: Require RNA primer. DNA polymerase cannot start synthesis independently. It requires: \[ \boxed{ \text{RNA primer} } \] The RNA primer provides:
• Free 3' OH end for DNA synthesis. Hence statement D is correct.

Step 5: Identify correct combination. Correct statements are: \[ A,\ B,\ D \] Thus: \[ \boxed{ \text{Option (4)} } \] Final Conclusion: DNA replication:
• Uses DNA polymerase
• Is semi-conservative
• Requires RNA primer Hence correct answer is: \[ \boxed{(4)\ A,\ B\ \&\ D\ Only} \]