Chapter 12 - DNA replication Flashcards
What is DNA replication?
process of duplication of DNA molecule
How does DNA replication work?
the parental strands separate and new partners are made, parental strand is a template strand for synthesis of daughter strand by complimentary base pairing
What is semiconservative replication?
in resultant DNA there is one original (parent strand) and one whole new strand (daughter strand)
What was the theory of conservative replication?
the resultant DNA the original remained the same and new DNA helix was both daughter strands
Who found out that DNA replicates semiconservatively?
Matthew Meselsohn and Franklin Stahl
How did Meselsohn and Stahl’s experiment work?
Isotopes of nitrogen with an extra neutron 15N was cultivated and transferred into solution of 14N nitrogen. After 1 round cell replication halted. and density of solution measured in a centrifuge
What was the result of meselsohn’s and stahls experiment?
Centrifuge separated one band of 15N and one of 14N suggesting that it was semiconservative
What is the replication fork?
where parental strands separate
What way do DNA polymerase synthesise?
5’ to 3’ direction, nucleotides added to 3’ end
What is DNA polymerase?
enzyme that synthesises a new DNA strand from an existing template
catalyses polymerisation reaction - nucleotide triphosphate is added to growing DNA strand
Which strand of DNA can be synthesised as one long continuous polymer?
leading strand
Which strand of DNA is synthesised in short pieces?
lagging strand
What are the short pieces in the lagging strand called?
Ohazaki fragments
What is a primer?
a short stretch of RNA that allows for start of synthesis of DNA strand
what is topoisomerase II?
enzyme that works at or near replication fork. it relieves the stress on double helix that results from unwinding
