DNA Replication Flashcards
What is DNA replication?
The synthesis of new DNA.
What does DNA replication allow? (2)
organisms to grow, tissue to regenerate
What are the 3 models of DNA replication?
Semiconservative, conservative and dispersive
What occurs in the semiconservative model?
The two parental DNA strands split to form 2 daughter DNA strands. New DNA is synthesised for both strands
What occurs in the conservative model?
Similar to a photocopy, the parent DNA remains ‘as is’, daughter DNA is a completely new copy.
What occurs in the dispersive model?
After replication both strands contain segments of parental and daughter DNA
What are the 3 requirements for DNA replication?
A template strand, raw materials (primer, nucleotides) and enzymes and other proteins.
Which direction is DNA synthesised in?
3’-5’
What does DNA helicase do?
Breaks down the H-bonds between two strands
What does DNA gyrase do?
controls supercoiling and reduces the torque built up by the replication fork
What makes RNA
Primase
What does DNA Polymerase III do?
The bulk of DNA replication. 5’-3’: adds nucleotides to the growing 3’ end. 3’-5’: removes wrong bases.
What does DNA Polymerase I do?
removes ribonucleotides (DNA Primer)
What are breaks in the DNA chain sealed by?
DNA ligase
Which method of DNA replication is used in all organisms?
Semiconservative
