Question

Approximately how many Okazaki fragments are synthesized in the replication of the E. colichromosome?

Short answer

Approximately $2300$to $4600$ Okazaki fragments are synthesized in the replication of the E. coli chromosome.

Step-by-step solution

Okazaki fragments.

In a double-stranded DNA molecule, the strands are antiparallel to each other and replicate simultaneously at the advancing replication fork. DNA polymerase enzymes help the replication in $5\text{'}$ $\to$ $3\text{'}$ direction only. One strand can be synthesized continuously while the other is replicated by creating Okazaki fragments.

Okazaki fragments in E. coli.

In E.coli, one strand of newly synthesized DNA contains 1000-2000 nucleotides long Okazaki fragments. The genome length of Escherichia coli is about $4.6\times {10}^6$base pairs.

For the entire replication of the E. coli genome, the number of Okazaki fragments required is:

No. of Okazaki fragments = Total length of the genome of the E.coli

Length of each Okazaki fragment

When the length of the Okazaki fragment is 1000 base pairs,

No. of Okazaki fragments = $4.6\times {10}^6$base pairs$=$$4600$

$1000$ base pairs

When the length of the Okazaki fragment is 2000 base pairs,

No. of Okazaki fragments =$4.6\times {10}^6$base pairs $=$ 2300

$2000$ base pairs