Question

Explain how DNA is replicated.Be sure to include the enzymes involved in the process.

Answer 1

DNA replication is the process by which new DNA are synthesis during the process of cell division and it happens in a semi conservative manner.(The newly synthesized DNA consists of one new strand and one parent strand).This happens in the following steps:

Unwinding of the DNA where the hydrogen bonds between adenine and thymine,cytosine and uracil are unzipped to form two strands which is carried out by the enzyme DNA helicase.

The separates strands then forms a replication fork which is the unit of replication and since the separate strands tend to unite they are held on by single stranded binding proteins (SSBPs) which stabilize the strands .

The replication fork so formed consisted of strand with polarity of 5’-3’ and one from 3’-5’ .The replication happens in a continuous fashion in the parent strand having polarity 3’-5’ and this is called the leading strand and the other is called the lagging strand

Initiation : Small fragments of RNA called the primers bind to the separated strands which is facilitated by the process of enzyme RNA primate.This serves as the starting step and initiated the replication.

Elongation : In this step the DNA polymerase III carries out the elongation of chains by adding the base pairs following the complementarity and the polumerizastion happens in the 5’-3’ direction .This leads to a continuous synthesis where leading strand is the template and discontinuous synthesis where lagging strand is the template called the Okazaki fragments.

Termination : Once elongation is done the proofreading takes place by the exonuvlease where the appropriate bases are incorporated.Finally the strands are joined by the enzyme DNA ligase