Replication of the E. coli chromosome starts at a particular point, the origin of chromosomal replication...

Replication of the E. coli chromosome starts at a particular point, the origin of chromosomal replication (oriC) and proceeds bidirectionally around the circular chromosome.

A. Describe how the strands at oriC are separated to allow replication of the chromosome.

B. Once the replication is initiated the process of bidirectional semi-discontinuous DNA replication occurs. Describe this process.

Expert Solution

A. Once the site of replication is recognised then certain proteins acts and form two Y shaped replication forks which together forms the replication bubble.

The enzyme called helicase binds here and its main function is to move the replication fork forward and it does so by breaking the hydrogen bonds and thus unwinding the dna strands.

Then some single strand binding proteins comes into play and binds to these single strands and it prevents there re winding.

B. The process is called semi discontinous because the DNA polymerase 3 enzyme used in replication in E.coli can replicate the strand which has direction as 3'-5' so but it cannot replicate the other strand called lagging and if it do so the two newly formed strands will bind thus here other enzyme called primase comes into play

Primase makes primers which attach from 3 to 5 end .primese are 5 to 10 nucleotide strands which will be then elingated by DNA polymerase 1 .

So as the leading strand (3'-5') is replicated continously and the lagging strand discontinously ,hence it is called semi continous.

gladiator answered 1 year ago

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