DNA 1 - MT2 - Part 2 Flashcards
How can a DNA molecule by copied?
By means of DNA polymerization reactions that are catalyzed by enzymes
Semiconservative
Relating to or denoting replication of a nucleic acid in which one complete strand of each double helix is directly derived from the parent molecule
- mix of old and new strands
Conservative
During replication, the 2 original strands of the DNA template stay together in a double helix and would produce a copy consumed of 2 new strands
- 2 different strands
What is the name of the enzyme responsible for DNA replication?
DNA polymerase
What can DNA polymerase do?
It can add nucleotides to the end of a pre-existing polynucleotide strand
- as long as another strand is there to serve as a template
What are the 3 steps in replication?
- Initiation
- Elongation
- Termination
What is a source of mutations?
Errors in DNA replication
What is the ultimate source of variation?
Mutation
What 3 things can you add into a test tube to get a replication outside of a cell?
- DNA polymerase
- Free nucleotides
- DNA
Ethidium bromide
Is a flat fluorescent molecule that can slide between the stacked base pairs of DNA
What happens when UV light is shone on ethidium bromide?
It absorbs the light and re-emits some of the energy as green light, telling you where the DNA is
What happens when a current is applied to a solution containing DNA?
The DNA molecules will be drawn to the positive pole
- electrophoresis
Why does DNA get drawn to the positive poles?
Because DNA has many negative charges on its backbone
Charge density
The electric charge per unit area of a surface or per unit volume of a field or body
What is separation speed through a gel based on? (3)
- Shape
- Charge density
- Length size
- shape and charge density will have the same results so the size is the only thing that will differ
What size of segments move faster?
Smaller ones
- compared to larger ones
Electrophoresis
Separation of molecules in an electric field, according to size
PCR
Polymerase chain reaction
What does PCR do?
It amplifies specific DNA segments
What does PCR depend upon?
DNA replication reactions
- which in turn depend on the phenomenon of specific base pairing
Who invented PCR?
Kelly Mullis
What year was PCR invented?
1984
What kind of reaction is PCR?
Cyclic reaction
- each cycle takes a few mins
What 5 things do you need for a PCR reaction?
- DNA template
- contains DNA molecule you want to amplify - Short DNA primers with sequences that flank the sequence you want to amplify
- this gives it specificity - Free nucleotides
- Taq polymerase
- Thermal cycler
What is an example of a DNA template?
Blood from a crime scene
Taq polymerase
A DNA polymerase, from a heat resistant bacterium, that can be heated without being destroyed
Thermal cycler
A small unit for your reaction tubes that can heat up quickly and cool down quickly
What does DNA replication need to begin the new strand?
A primer
- the process cant just begin anywhere
What happens in the PCR cycle? (4)
- The thermal cycler heats up and the DNA is denatured to 2 separate polynucleotide strands
- The thermal cycler is cooled, the single stranded primers anneal to their complementary sequence on the target gene
- The taq polymerase extends the primers, making a new DNA strand that is complementary to one of the target strands
- The thermal cycler is heated again, the DNA double helixes melt and a new cycle begins
What happens to the amount of DNA after every cycle?
It gets doubled
