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DNA is replicated by the semi-conservative model. Describe this process in eukaryotes (linear chromosomes). Include what...

DNA is replicated by the semi-conservative model. Describe this process in eukaryotes (linear chromosomes). Include what enzymes are involved and what is their role in the process? What happens at the ends of linear chromosomes?

Expert Solution

Answer=

Semiconservative replication of DNA in eukaryotes-

DNA replication in eukaryotes occur only in S-phase of cell cycle.Eukaryotic DNA has many origins of replications

Steps=

1.Initiation - The first step is formation of pre-initiation complex.It occurs in 2 stages.

-The replication begins with the binding of ORC to the origin.ORC is a hexamer of related protein and remains bounded even after DNA replication occurs.

-After binding of ORC to origin MEM complex i.e.mini chromosome maintainance is major helicase.

-Enzyme is MCM -acts as helicase.

2.Elongation -DNA polymerase delta synthesizes and adds dNTPs at 3'end of RNA primer.

THE leading and lagging strands are synthesized in the similar fashion as in prokaryotic DNA replication.

enzyme -

Replication protein A - acts as single stranded binding protein keeps the separated strands separate.

DNA polymerase alpha- acts as primase.initiates the process of replication.

DNA polymerase delta- acts as replicase,main enzyme synthesizing new DNA strands.

Topoisomerase I & II -

3.Termination -AT the end of DNA replication the RNA primer are replaced by DNA by 5'-3' exonuclease and polymerase activity of DNA polymerase .

The ends of linear chromosome is called as telomere.

Telomerase is a DNA polymerase i.e. RNA dependent DNA polymerase which adds many copies of telomere sequence at 3'-OH end of template strand.

like other polymerases,telomerase also adds deoxyribonucleotide at 3'-OH end.

gladiator answered 2 years ago

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