Ch 12 DNA Replication Flashcards
What did Meselson and Stahl confirm was the correct replication model?
semiconservative replication
What experiment did Meson and Stahl complete to confirm their theory?
They used density labeling to distinguish parental and daughter strands. The parent N14—– to N14/N15 I the 1st generation—— then half n14/N15 and half N14/N14
How is the leading strand synthesized?
Continuously in the 5’ to 3’ direction
How is the lagging strand synthesized?
In small pieces called Okazaki fragments with multiple primers
strand replication process
Dna is unwound and operated creating a fork, an RNA primer (that is complementary to the DNA template) is added at the 5’ end of the parental strand, DNA polymerase add nucleotides off of the primer
How to Okazaki fragments join together?
The RNA primer is extended by DNA polymerase then removed and the primer is replaced with DNA from a different DNA polymerase and the fragments are then joined by DNA ligase
What is topoisomerase
Relieves DNA unwinding stress by cutting dna, unwinding, then rejoining the two strands
What does Telomerase do?
adds telomere sequences to ends of DNA to protect and prolong division. It contains an RNA sequence that acts as a template. Without it the strand would get smaller and smaller until there was no more DNA.
Where is PCR performed?
In the laboratory to amplify segments of DNA
What are the three steps of PCR?
- Denaturation by Heat
- Primers are annealed to the DNA strands
- DNA is elongated by TAQ polymerase which does not denature in heat.
What is the point in gel electrophoresis?
The separate DNA by size
How does gel electrophoresis work?
Dna fragments are run through a gel, then an electric field is applied that negatively charged fragments move towards the positive end.
What are restriction enzymes?
enzymes that cleave DNA at specific sequences which create restriction sites. They are the same sequence reversed.
What is southern blotting?
DNA fragments are added into gel electrophoresis, then transferred or blotted onto filter paper, probed with complementary base pairs that will light up if they find their match
Snager method
The template strand is unknown so they elongate the daughter stand then separate it by size and tag it with floursence
