DNA replication Flashcards
what process does DNA replication need to occur for
DNA replication has to occur before cell division , so that daughter cells have full compliment of genome
what is meant when it is said DNA replication is semi-conservative
the two strands remain intact, separate and are both copied individually
what enzyme catalyses DNA replication and what are its limitations/requirements
DNA polymerase, can only add to existing nucleic acid, cant start DNA synthesis themselves, require RNA primer to start
what is meant by the term origins of replication
this refers to the fact that replication starts simultaneously at several points along the genome and so there are several points of origin. this is bidirectional and ensures replication is done in reasonable time
why is DNA replication discontinuous
because nucleotides can only be added to a free 3’ end, so one of the strands has to be replicated in fragments(lagging strand)
describe DNA replication of both the leading and lagging strand
leading strand, always has a free 3’ end so replicates continuously
lagging strand, has to use short RNA primers and replicate DNA in short fragments(okazaki) because there is not always a free 3’ end
what enzyme is needed to unwind the DNA helix and stop in rewinding during replication
helicase
what shape is the DNA helix changed to during replication
a replication fork with the leading and lagging strand getting further away from each other
what can go wrong during DNA replication and how is it repaired
if a wrong nucleotide is incorporated it can cause a mutation, DNA polymerase removes incorrect nucleotides along with other repair systems
