DNA Replication
DNA replication is a biological process of producing two
identical replicas of DNA from one original DNA molecule.
DNA is a double helix that is made up of two complementary
strands.During this process of replication these 2 strands are
separated.
The main basic 3 steps of DNA replication are
initiation,elongation and termination.
- There is an enzyme called DNA helicase , this
enzyme helps in the unzipping of the double stranded DNA .
- The DNA helicase enzyme breaks the hydrogen bonds so that the
strands are separated into two individual strands.
- This separation is aided by another enzyme called
topoisemerase , this enzyme holds the 2 DNA
strands apart while the DNA helicase does its job.
- When the 2 strands are separated another enyzme called
DNA polymerase starts to attach free DNA
nucleotides from the 5' end to the 3'end.
- The DNA Replication always takes place in the 5' end to
3'end.
- Nucleotides are added by complementary base pairing i.e,
Adenine only binds to thymine and cytosine only binds to
guanine.
- In one strand the addition of nucleotides is continuous and
this strand is called leading strand while in the other strand the
addition of nucleotide is fragmented and this strand is called
lagging strand.
- The lagging strand is done in short fragments called
Okazaki Fragments.
- After the DNA polymerase has added fragments to the lagging
strand then these fragments are joined together by DNA ligase to
create a complete strand.
- DNA replication is classified as a semi-conservative
process.
- In DNA replication the new strands are joined to the template
strands to create a complete or full DNA helix , which means that
it contains half old and half new strands.
- This process takes place in all the cells of the body.