LEC DNA REPLICATION

dna replication

takes place by separation of the strands of the double helix and synthesis of two daughter strands complementary to two parental templates

semiconservative

when new parental strands separate and form new dna complementary strand

dna polymerase

responsible for the synthesis of new dna strands from dna templates

5’ to 3’ direction

which direction does polymerization occur

3’ hydroxyl terminus

provided by the dna polymerase primer

dna polymerase 3

multi subunit complex

semiconservative, requires primer, semidiscontinuous, bidirectional, ordered, sequential and highly accurate

general features of dna replication

leading strand

replicated continuously in the direction of the replication fork

lagging strand

replicated discontinuously as okazaki fragments in the opposite direction

origin site

where does replication start?

replication fork

points where a pair of replicating segments come together and join non replicated segments

oriC

origin of replication of e coli

dnaa

binding site for protein in ecoli replication fork

dnab and single stranded dna binding proteins

proteins that unwind the parental duplex and separate the two stands

primase and helicase

forms primosome which progressively moves along the lagging strand template

dna gyrase

relieves the tension by changing the dna into a negatively supercoiled dna

unwinding process

when is tension built up?

positively supercoiled

the dna becomes _____ when the unwinding process begins

atp hydrolysis

what is used when dna tension is being relieved?

replisome

consists of holoenzyme, helicase, ssbs and primase