Question

Describe how DNA is replicated using the following terms: DNA helicase, single-strand binding proteins, ori, primase, primer, DNA polymerase, replication fork, leading strand, lagging strand, Okazaki fragments, DNA ligase, 3',5', sliding DNA clamp.

Answer 1

DNA is double stranded.In firsr step helicase binds at ori ( which is the site of origin of replication ) and unwinds the DNA by breaking hydrogen bonding and open replication fork and two strands are separated one is leading and other is lagging strand.Leadung strand is a continuous strand while lagging strand is discontinuous on which okazaki fragments are fomed. Synthesis always takes place in direction 5' to 3'.As the helicas starts unwinding SSB ( single stranded binding protein ) binds to single stranded DNA so that the unwind DNA cannot make helix again.After this primase binds and synthesise short RNA primers.Then DNA Polymerase binds at beta clamp which is also known as sliding clamp binds at the primer and add nucleotides to the primer and elongate dna.Okazaki fragments formation takes place at lagging strand.