DNA strands- the leading strand is made

 DNA is known as nucleic acid that bears
genetic information. Its structure was deduced as a double helix due to that DNA
carries out one of the main functions- replication, which is the process when DNA
copy itself during the cell division. Therefore, in this essay I am going to
describe bacterial DNA replication in more detail.

To begin
with, a bacteria uses one origin of replication. Thus, the enzyme helicase separate two
parental DNA strands and makes a replication fork.  This provides templates for creating a new
strand of DNA. An enzyme primase
starts the process- produce a small piece of RNA- primer, which marks a
starting point for a new structure of DNA. It follows that DNA polymerase III binds
to the primer and add DNA bases in only one direction from 5′ prime end to 3′
end. Accordingly, one of the new strands- the leading strand is made towards the replication
fork when DNA polymerase III accomplice with the DNA clamp , which encloses the double helix and
continuously synthesizes. However, the other strand- lagging can not be made in
this continuous way because it runs in opposite direction, it can be seen in
the diagram, which presented below. A primase joins RNA nucleotides into a
primer. Then DNA pol III adds DNA nucleotides to the primer, forming first Okazaki fragment .After the
DNA pol III detaches from DNA when reach the next primer on the right. Then
second fragment is primed. DNA
polymerase I removes the RNA primer and replaces it with DNA, adding to
the 3′ end of fragment 2 . When two strands are made, enzyme exonuclease removes all
the RNA primers from both strands of DNA, then another DNA pol fills in the
gaps with DNA. Finally, the enzyme DNA ligase seals up the fragments of DNA in both strands to form
a continuous double strand.

conclusion, the DNA replication continuous in both directions until the
replication forks meet on the other side in two daughter DNA molecules and is called
semi-conservative because made of one old- conserve strand and one new. There
are key proteins, which are involved into this process: helicase, primase, DNA
clamp, DNA pol III, DNA pol I, exonuclease and DNA ligase.


I'm Mary!

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