Intro To Molecular Biology 2 Flashcards
How are DNA strands copied?
Semi-conservative model
1st gen = 1 parental strand
2nd gen = 50% have 1 parental strand
How is DNA replication sped up?
Replication takes place at many different sites simultaneously
In what direction is DNA replicated?
5’ to 3’
What is the replication fork?
Structure formed in DNA replication
DNA helical pulls two strands of DNA apart - each strand template for replication
Asymmetrical
What’s the leading strand?
DNA synthesised same direction as growing replication fork
5’ to 3’
What’s the lagging strand?
DNA synthesised opposite direction to replication fork
Forms Okazaki fragments - joined by DNA ligase
What does DNA polymerase do at the lagging strand?
Adds RNA primer to start new Okazaki fragment
DNA polymerase finishes DNA fragment
Old RNA fragment erased + replaced by DNA
Differences between template strand and newly synthesised lagging strand:
Template strand = repetitive telomere sequences
Newly synthesised lagging strand = incomplete
What happens at DNA end to complete the lagging strand?
Telomerase adds additional repeats to template strands
Allows for completion of lagging strand’s synthesis by DNA polymerase and ligase
When can mutation be adjusted?
During synthesis
Post-replication
WHat’s PCR?
Polymerase chain reaction - allows replication of DNA to make large amounts
What happens during PCR?
DNA is heated - separates strands and primers
Polymerases added to synthesise new SNA
What’s the PCR useful for?
To identify presence of infectious agents
To identify inheritance patterns
How is presence of infectious agents identified using PCR?
Blood sample
Cells removed by centrifugion
DNA extracted and undergoes PCR
Gel electrophoreis used to compare blood
