Lectrure 3 Flashcards
What is DNA replication
It’s a molecular process in which genomic DNA is copied in cells before it divides
What is complementary
The matching base pair bonds
Dose the strand separate fully
No
What is lost is the replication reaction
2 phosphate
What is semi conservative
2 newly copied daughter DNA molecules will have 1 old parent strand and 1 newly made strand
Where dose replication begin
Original of replication sites (Ori)
What are ori sites usually marked by
A particular sequence of nucleotides usually AT rich
Why is the ori sites usually AT rich
There is only 2 binds to be broken so they are weaker
How many ori sites in a bacterial genome
1 cause they are small
How many ori sites in the human genome
10000 cause there is a lot of replication occurring
What is the opening of the 2 strands called
The replication bubble
What at the end of each bubble
Replication forks
What is a replication fork
A y shaped region where the new strands are elongating
What direction is DNA replication
Bidirectional
What dose elongating of the new strands of DNA involve
Incorporating a new nucleotide into the strand using nucleotides that match their partner on the template stands
Where dose elongation occur
At the replication fork where enzymes called DNA polymerase catalyse the addition of the new nucleotides to the new strand at the 3’ end
What dose the DNA polymerase catalyse
The addition of the nucleotides at the 3’ end by forming a new phosphodiester bind between 3’ OH end of the last nucleotide into the strand and 5’ phosphate group of the incoming nucleotide
What happens to the nucleotide mono phosphates
It is added to the strand
What happens to the pyrophosphate
It is realised and hydrolysed to 2 inorganic phosphate molecules
What DNA polymerase are used for bacterial replication
DNA polymerase 1 and 3
What is the main DNA polymerase used in eukaryotic DNA replication
Delta
What direction can DNA replicate
5’ to 3’ direction
What is the leading strand
The strand synthesising in the 5’ to 3’ continuously
What is the lagging strand
The strand that synthesising in the 5’ to 3’ direction discontinuously
How is the lagging strand synthesised
In series of fragments
What are the fragments of the lagging strand called
Okazaki fragments
What dose DNA ligase do
Joins the sugar phosphate backbone of the Okazaki fragments together
Is the replication fork asymmetrical
Yes
