Question

A circular molecule of DNA contains 1 million base pairs. If the rate of DNA synthesis at a replication fork is 100,000 nucleotides per minute, how much time will replication of this circular chromosome take by rolling-circle replication? Ignore replication of the displaced strand in rolling-circle replication.

Answer 1

It will take 10 minutes to replicate a circular DNA molecule containing 1 million base pairs at a rate of 100,000 nucleotides per minute by rolling-circle replication, assuming only the replication of the leading strand.

Step-by-step explanation:

To calculate the time it will take to replicate a circular chromosome by rolling-circle replication, we use the given values: the chromosome has 1 million base pairs, and replication occurs at a rate of 100,000 nucleotides per minute. Since rolling-circle replication only involves one replication fork, we can directly divide the total number of nucleotides to be replicated by the rate of replication.

The total time required for replication would be:

• Total base pairs: 1,000,000 base pairs
• Rate of synthesis: 100,000 nucleotides per minute
• Time for replication = Total base pairs / Rate of synthesis
• Time for replication = 1,000,000 base pairs / 100,000 nucleotides per minute = 10 minutes

It will take 10 minutes for the circular DNA molecule to replicate completely using rolling-circle replication, not considering the replication of the displaced strand.