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Discontinuous synthesis of DNA occurs i...

Discontinuous synthesis of DNA occurs in one strand, because

A

DNA molecule being synthesised is very long

B

DNA dependent DNA polymerase catalyes polymerisation only in one direction (5'`to`3')

C

it is a more efficient process

D

DNA ligase has to have a role

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### Step-by-Step Solution: 1. **Understanding DNA Structure**: DNA is composed of two strands that run in opposite directions, known as antiparallel strands. One strand runs from the 5' to 3' direction, while the other runs from 3' to 5'. 2. **Role of DNA Polymerase**: The enzyme responsible for synthesizing new DNA strands is DNA-dependent DNA polymerase. This enzyme can only add nucleotides to the free 3' end of a growing DNA strand. 3. **Direction of Synthesis**: DNA polymerase synthesizes DNA in the 5' to 3' direction. This means that it can only add nucleotides to the 3' end of the new strand being formed. 4. **Continuous vs. Discontinuous Synthesis**: - The strand that runs in the 5' to 3' direction can be synthesized continuously as the replication fork opens up. - The strand that runs in the 3' to 5' direction cannot be synthesized continuously because DNA polymerase cannot add nucleotides in that direction. Therefore, this strand is synthesized in short fragments, known as Okazaki fragments, leading to discontinuous synthesis. 5. **Conclusion**: The discontinuous synthesis of DNA occurs in the strand that runs from 3' to 5' because DNA polymerase can only synthesize DNA in the 5' to 3' direction. This results in the formation of short segments of DNA on this strand. ### Final Answer: Discontinuous synthesis of DNA occurs in one strand because DNA-dependent DNA polymerase can only catalyze polymerization in the 5' to 3' direction, leading to continuous synthesis on the 5' to 3' strand and discontinuous synthesis on the 3' to 5' strand. ---

### Step-by-Step Solution: 1. **Understanding DNA Structure**: DNA is composed of two strands that run in opposite directions, known as antiparallel strands. One strand runs from the 5' to 3' direction, while the other runs from 3' to 5'. 2. **Role of DNA Polymerase**: The enzyme responsible for synthesizing new DNA strands is DNA-dependent DNA polymerase. This enzyme can only add nucleotides to the free 3' end of a growing DNA strand. 3. **Direction of Synthesis**: DNA polymerase synthesizes DNA in the 5' to 3' direction. This means that it can only add nucleotides to the 3' end of the new strand being formed. ...
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