DNA Replication In Prokaryotes Flashcards
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In which phase of mitosis does replication occur
Synthesis
DNA replication is semi conservative. This means?
One of parents strands serves as template to form other strand. Observed from Messelson and Stahl Experiment
In Meselson and Stahl experiment, bacteria are cultured for how many generations
- In N15 first. Then N 14
In cairns experiment bacterial cells are labelled with
3-H thymidine
What is the replication fork?
Proteins and enzymes needed for DNA replication assembled at origin of replication
Replisome
:All proteins and enzymes needed for replication
Replicative helicase has how many subunits
6
Function of DNA Polymerase
Polymerizqtion of deoxyribonucleotides. Elongation of daughter stand
Helicase
Unwinds DNA
Primase
Synthesises RNA primer
Topoisomerases
Relieve overwinding ahead of replication fork and decatenate the final product
Relieves torsional strain from helicase induced winding
Single strand binding protein
Stops single strand(lagging) from folding into secondary structure
Y clamp complex loader
Loads beta sliding clamp on leading and lagging strand
B sliding clamp
increases progressivity of dNA polymerase. Without it polymerase would fall off
Ligase
Seals nick between okazaki fragment and okazaki fragment
Synthesis on lagging strand is semi discontinuous. What does this mean and why does it occur
It means does synthesis occurs in bits because synthesis occurs opposite the direction of the replication fork.
What is the byproduct of polymerase adding dntps
Piphosphate
Which ligase joins okazaki fragments
DNA ligase 1
Properties common to all DNA polymerased
Catalyse the polymerisation of deoxyribonuvleotides in the 5’ to 3’ direction
Require a template
Require a primer
What is the difference between DNA polymerase 1 and 3
DNA polymerase 1 is responsible for replacing RNA primers with DNA by nick translation
DNA polymerase III is the main replicase
What are the other subunits of the DNA polymerase holoenzyme
Y complex, B subunit, T subunit(holds two polymerase 3 cores together)
DNA Polymerase I was discovered in … by …
Late 50s, by A Kornberg
How long aree okazaki fragements
1000 to 2000 base pairs long