DNA Replication Flashcards
Why is folic acid cycle important?
Provides essential C 1 donors for synthesis of DNA via folic acid cycle
What are formyl donors involved in?
Purine biosynthesis
What are methyl donors involved in?
Pyrimidine biosynthesis
Why is topology of DNA important?
Supercoils
Knotting
Catenation
What are topoisomerases?
Enzymes that regulate topology of DNA
What are the topoisomerases?
Topoisomerase I = cuts 1 strand
Topoisomerase II = cuts 2 strands
What does DNA helicase do?
Separate double-stranded DNA into single strands so they can be copied
What do helicases use?
Energy of ATP to break H bonds between base pairs
What happens in synthesis from 5’3 direction in leading strand?
Synthesis in all one go
What happens in synthesis in lagging strand?
Synthesis in chunks
What is primase?
Before nucleotides can be added to “unzipped” DNA a primer is added
= starting point of DNA synthesis
What are the different DNA polymerases found in eukaryotic cells?
α, β, Υ, δ and ε
What do DNA polymerases do?
Add nucleoside triphosphates to growing DNA strand in 5’ to 3’ direction
What is the fidelity of DNA replication?
Putting “wrong” base is way less favourable than “right” base
DNA polymerase also has 3’ to 5’ exonuclease activity
“Mismatch” enzyme repair system = checks helix
What can all DNA polymerase only make DNA in?
5’ to 3’ direction
