1.3.4 - DNA Replication

Question 1

What is the first stage of DNA replication?

Answer 1

DNA helicase attaches to the DNA. Beaks hydrogen bonds between bases so polynucleotide strands separate from each other.

Question 2

What happens after polynucleotide strands separate?

Answer 2

Free nucleotides line up with their complementary bases.
These free nucleotides are called activated nucleotides - 3 phosphates

Question 3

What forms phosphodiester bonds between activated nucleotides and DNA bases?

Answer 3

DNA polymerase
in a condensation reaction

Question 4

What happens to activated nucleotides after phosphodiester bonds are formed?

Answer 4

They lose 2 phosphate groups providing energy for the reaction

Question 5

What type of DNA replication is this?

Answer 5

Semi conservative replication

Question 6

Why and when is DNA ligase used?

Answer 6

DNA polymerase can only build a new strand from the 5’ to 3’ end.
So on the lagging strand, DNA polymerase forms a strand of DNA in a series of shorter strands joined by DNA ligase.

Question 7

What’s the role of DNA helicase?

Answer 7

Separates strands of DNA by breaking bonds in the 5’ to 3’ direction

Question 8

What’s the role of DNA primase?

Answer 8

Allows the function of DNA polymerase through RNA primers.