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• Prokaryotic Initiation of Replication: formation of replication forks and star

ID: 193114 • Letter: #

Question

• Prokaryotic Initiation of Replication: formation of replication forks and start of polymerization

o What are the names of the binding sites contained in the replication origin and what proteins do they bind?

o What role does the enzyme Dam methylase play in the initiating replication?

o Describe the roles of DnaA, DnaB, DnaC•ATP, and Hu proteins in the initiation of prokaryotic replication.

o What is the DUE region in the replication origin and what role does it play in initiation of prokaryotic replication?

o Is primase (DnaG) required for the initiation of replication?

What role does primase play in replication? Is that role necessary for replication to begin?

o What is the function of DNA Gyrase?

o Put all of the above together and tell the story of the initiation of prokaryotic replication.

• Describe the function of ORC, Cdc/Cdt complex, MCM, and Cdc45 protein complexes in the initiation of eukaryotic replication.

• Elongation of the DNA polymer: prokaryotic replication

o What is the primary function of DnaG during elongation? Why is this necessary?

o Tell the story of the actions of DNA Pol I and III during elongation.

o What is the function of single strand binding proteins (SSB)?

Are SSB found primarily on the leading or lagging strand?

o Where is helicase found in the replisome?

o Does the subunit of DNA Pol III remain bound to both strands of DNA during replication? Why?

Explanation / Answer

DnaA helps to unwound the ori and thus replication to proceed.

DnaB-opens the replication fork during replication, it is a helicase.

DnaC.ATP-it is the loading factor of helicase DnaB

Hu protein-resembles the eukaryotic Histone H2B, inser negative supercoiling along with the topoisomers

DUE (DNA unwinding element)region- it is the region where initiation of DNA unwinding happens at the ori.

DnaG- without it DNA replication won't happen.DNA polymerase requires a 2'OH for initiating the olymerisation reaction.dnaG are the DNA primase which add short RNA strands (which has 2'OH).