Modules 1 & 2 Flashcards
(92 cards)
What did frederick griffith do
Catalogued bacteria
2 viral strains - Griffiths
Rough small = Avirulent
Smooth large = Virulent
Transforming principle
Observation that an element of dead bacterial cells can transform avirulent bacterial cells into virulent
Griffith experiment
Treated rough strain with heat killed smooth strain, the new strain was now virulent
Avery-Mccarty-Mcleod experiment
Proved that DNA was the transforming component in the strain through adding enzymes such as DNAse to see which survived
Franklin & Wilkins
Used X-ray diffraction to identify a double helix structure
Chargraff
determined that base pairings had equal amounts of corresponding nucleotides
Conservative replication
Replication results in a molecule containing parental dna and a new strand
Semi conservative replication
Original DNA is split into 2 where one acts as a template for a new strand
Dispersive replication
Original DNA is chopped up and dispersed in a strand
Components of replication fork
- Helicase
- Pol E
- PCNA
- Pol A
- Pol D
- RPA
- RFC
Helicase function
Unwinds parental DNA using ATP
Pol E function
Replicative polymerase that extends leading strand
Pol D function
Replicative polymerase that extends the lagging strand, associates with PCNA
PCNA function
Acts as a clamp holding Pol E and D, stabilises them
Pol A function
Makes a complex with primase to synthesise primers for the lagging strand
RFC function
Clamp loader which opens the PCNA ring to enclose the DNA synthesised by Pol A
RPA function
binds to ss DNA to extend it , orientate it and protect it
Prokaryote replication
Has one point of origin, DNA unwinding site rich in AT
Eukaryote origin replication complex
Made of 6 proteins and loads CD factors, defines the orgins (pre-licensing)
What are replicons
Made of 2 replication forks which initiates synthesis
What is the initiation of DNA replication synchronised with
Cell cycle
What controls the cell cycle
Cyclins and cyclin dependant kinases
Cyclins and their roles
- B = block DNA synthesis
- D = activate G1/S cyclins
- E = restriction point
- A = Activates helicase