24. A bacterium has a genome of size 6 million base pairs. If the average rate of DNA synthesis is 1000 base pairs/second, the time taken (in minutes) for replication of the genome will be _________.
Bacterial genome replication time hinges on genome size and DNA synthesis rate. For a 6 million base pair genome at an average rate of 1000 base pairs per second, replication completes in 100 minutes.
Calculation Breakdown
Genome size stands at 6,000,000 base pairs. DNA synthesis rate measures 1000 base pairs per second. Time calculation divides genome length by synthesis speed:
6,000,000 ÷ 1000 = 6000 seconds
Convert seconds to minutes:
6000 ÷ 60 = 100 minutes
Why This Approach Works
Bacterial chromosomes replicate bidirectionally from a single origin, forming two replication forks. Combined fork rates often equal about 2000 bp/s in species like E. coli.
However, the question specifies “average rate of DNA synthesis is 1000 bp/s”, implying this is an effective whole-genome speed used directly for calculation.
Thus, full genome division is correct, yielding 100 minutes.
Common Pitfalls
Students sometimes divide by fork number and mistakenly get 50 minutes. This applies only when rates are stated per fork.
Here, the phrasing refers to overall synthesis rate.
Reference Values
- Typical bacterial rate: ~1000 bp/sec
- Eukaryotic rate: ~50 bp/sec
- E. coli example: 4.6 Mb replicated in ~40 min at ~2000 bp/sec total
Relevance to Biotechnology
Understanding replication kinetics supports:
- Bioreactor growth phase modeling
- Gene knock-in timing predictions
- Metabolic engineering and synthetic biology workflows
Final Answer
Total time required = 100 minutes.
