Lecture 4 Flashcards
What is the polymerisation activity
It’s the catalyses addition of nts to free 3’ OH on growing DNA strand. Nts enter reaction as nucleoside triphophates. Breakage of phosphoanhydride bond in incoming nucleoside triphosphate releases large amount of free triphosphate releases large amount of free energy and provides energy for reaction
What is proofreading
The way DNA corrects itself due to the mistakes it makes
How many DNA polymerase are in prokaryotes
5
How many DNA polymerase in eukaryotes
14
What is the main DNA polymerase in bacterial replication
DNA polymerase III
What is the 2 activity’s that DNA polymerase carry’s out in bacterial replication
A forward DNA polymerase activity requiring a 3’ primer site and template strand
A reverse exonuclease activity that mediates proofreading
What dose DNA polymerase I do
Replaces RNA in primer with DNA and possesses three enzymic activitys
What are the 3 enzymic activity of DNA polymerase I
A forward DNA polymerase activity requiring a 3’ primer site and a template strand
A reverse exonuclease activity that mediates proof reading
A forward exonuclease activity mediating nick translation during RNA repair
What do DNA polymerase reply on to make new DNA
Short lengths of RNA primers
Can DNA polymerase start a new strand of DNA by itself
No it needs something to advance
What do an enzyme do in rDNA replication
It dose not synthesise DNA DNA but makes short lengths of RNA using DNA as a template
How many primers are in the leading strand
1 at ori site
How many primers are in the lagging strand
Many they are needed continuously
What dose Nuclease do
Breaks apart the RNA primer
What dose DNA polymerase I in bacteria do
Replaces RNA with DNA
What dose DNA ligase do
Joins 5’ phosphate end of one new DNA fragment to 3’ OH end of the next
What dose DNA ligase require to work
ATP
What dose helicase do
It’s an enzyme that uses energy of ATP hydrolysis to speed along DNA and separate strands of parental DNA double helix ahead of the polymerase (breaks the H bonds between base pairs)
What is a sliding clamp
It keeps DNA pol attached to DNA template. On the lagging strand the sliding clamp releases polymerase from DNA each time an Okazaki fragments is completed
What do single binding proteins do
They bind to separated single stranded SNA exposed by helicase which prevents it from reforming base pairs which provides access for primate and polymerase
