DNA Replication, the Cell Cycle and Mitosis Flashcards
Which enzyme unravels DNA?
Topoisomerase
Which enzymes separates the two strands?
DNA helicase
Which enzyme adds nucleotides to unwound DNA strands?
DNA polymerase
Does the separation of the two strands of DNA require ATP?
Yes
What two molecules are needed for DNA polymerase to do its job?
Oligonucleotide primers and dNTP’s (deoxynucleotide triphosphate)
Which direction does DNA synthesis occur?
5’ to 3’
What is the point where DNA synthesis begins called?
Origin of replication
Explain how the lagging strand is synthesised
DNA primase primes the DNA with an RNA primer that it synthesises. DNA polymerase then adds nucleotides to the 3’ end of the primer. When it meets the previous Okazaki garment the RNA primer of the previous one is removed by ribonuclease and replaced by Repair DNA polymerase then DNA ligase joins the two DNA strands.
Which enzyme synthesises the RNA primer for the lagging strand?
DNA primase
Which enzyme removes the RNA primer?
RIbonuclease
Which enzymes joins the DNA of Okazaki fragments?
DNA ligase
What makes sure the DNA polymerase is in the right place?
Sliding clamp
What prevents the single stranded DNA from locally folding?
Single stranded DNA binding protein
Which enzyme replace RNA with DNA?
Repair DNA polymerase
What is the DNA proofreading mechanism and what enzyme carries it out?
DNA polymerase checks the previous nucleotide is correct before adding another
