M5: DNA replication

Question 1

What are the requirements for successful DNA replication?

Answer 1

• DNA has to be unwound from its spiral configuration before strands can be separated
• enzymes are required to control the large number of physical and chemical reactions
• 2 strands of DNA run anti-parallel and nucleotides can be added in one direction only
• DNA replication errors must be corrected

Question 2

what does helicase do?

Answer 2

enzyme which uses energy to unwind dna strand and breaks down weak hydrogen bonds between nucleotide bases

Question 3

what happens after dna strands are seperated?

Answer 3

• replication fork forms
• ssb bind to and stabilise newly separated DNA strands

Question 4

whats the process of adding nucleotides?

Answer 4

• primer is added (RNA)
• dna polymerase adds dna nucleotides to new strand, picking them up in the floating nucleus

Question 5

how are DNA replication errors corrected?

Answer 5

• dna polymerase I backtracks and proofread
• splices out incorrect bases and replacing
• ligase seals 2 strands together (joins okazaki fragments together as well)