Question

The nuclear genome of a single human cell (i.e., the entire diploid complement) contains about 6.6 billion (6.6 × 109) base pairs of DNA. If synthesis at each replication fork occurs at an average rate of 50 nucleotides per second, all the DNA is replicated in 5 minutes. Assume that replication is initiated simultaneously at all origins. How many origins of replication exist in a human diploid genome?

a) 100
b) 500
c) 1000
d) 2000

Answer 1

The human diploid genome contains about 6.6 billion base pairs of DNA and can have up to 100,000 origins of replication. Based on the given replication rate, there are approximately 2,200 origins of replication in a human diploid genome.

Step-by-step explanation:

The human diploid genome contains about 6.6 billion base pairs of DNA. There are multiple origins of replication on each eukaryotic chromosome, and humans can have up to 100,000 origins of replication across the genome.

Based on the information given, replication occurs at an average rate of 50 nucleotides per second. If all the DNA is replicated in 5 minutes, we can calculate the number of origins of replication as follows:

6.6 billion base pairs / (50 nucleotides/second x 60 seconds/minute x 5 minutes) = 2,200 origins of replication.

Therefore, the correct answer is d) 2000.