DNA replication Flashcards
When does DNA replication happen in the cell cycle
Interphase - s phase
Semi conservative
DNA replication
Parent strand paired with daughter strand
Parent strand acts as template
DNA replication
Strands separate , hydrogen bonds break due to DNA helicase
Both strands acts as a template
Free nucleotides attach
Complementary base pairing
DNA polymerase joins nucleotides
H bonds reform
Semi-conservative replication
DNA helicase role
Breaking hydrogen bonds to separate strands
Strands then used as template
DNA polymerase role
Joins nucleotides via a phosphodiester bond (+ condensation reaction) to form sugar-phosphate backbone in new strand
Why is complementary base pairing important in DNA replication
Ensures new dna strand is exact copy of old DNA as it allows one strand to act as template to build new strand from
Why arrows point in different directions
DNA strands run in anti parallel
Different ends of DNA have different molecular shapes
Only one end has complementary shape to active site of DNA polymerase
To from e-s complex so new nucleotides can be joined together at that point
Explain why they used isotopes of nitrogen in their experiments
Labels nitrogenous bases in dna
By using heavy nitrogen first, labels parental dna so it can be traced through generations
By then moving to light nitrogen any new daughter strands will be traced and can be distinguished from parent strands
