DNA Profiling Flashcards
What is a genome?
-all the genes possessed by an individual or an organism
-99% the same across humans
What are exons?
-code for proteins
What are introns?
-non coding sections of DNA
-gene expression control
What is satellite DNA?
-repeated sequences in introns, centromeres + telomeres
What are the 2 types of satellite DNA?
- Mini
- Micro
What is minisatellite DNA?
-VNTR’s
-20-50 base paris repeated 50-100 times
What is microsatellite DNA?
-STR’s
-2-4 base pairs repeated 5-15 times
What is a telomere?
-repeated at the end
-where satellites are found
-diff people have diff no.of repeats = satellite patterns
What does DNA profiling help do?
-helps identify an individual + determine familial relationships
What are the 7 steps of DNA profiling?
- Extract DNA
- PCR
- Restrictive endonucleases
- Electrophoresis
- Southern blotting
- Hybridisation
- Seeing evidence
What does PCR do?
-amplify DNA sample
What is PCR?
-artificial DNA replication
-to amplify DNA fragment for further processing
What happens during restrictive endonucleases?
-cut large fragments into satellites
-they have active complementary site to the base
-in introns (satellites intact)
What happens during electrophoresis?
-agar jelly emerged in alkaline to break H bonds
-strands placed at negative end
Why are the strands placed at negative pole during electrophoresis?
-DNA has a phosphate group which = negative
-repelled from - and travels to +
What happens during southern blotting?
-blot DNA onto nylon sheet
-transfers pattern
What happens during hybridisation?
-add dye
-heat + UV light to fix pattern in place
=evidence to see
What are probes?
-fragments of DNA or RNA complementary to satellites that were selected
-can be radioactive or florescent
What are primers?
-short DNA sequences that anneal to DNA section that is wanted
What are the 3 stages of PCR?
- Denaturation
- Annealing of primers
- Extending/synthesis
What happens during denaturation?
-increase KE = vibration
-bases separation from their complementary bases
-breaks H bonds
What temperature does denaturation occur at?
95 c
What happens during the annealment of primers?
-design primers to recognise target DNA
-to be amplified
What temperature does annealing occur at?
55 c
What happens during extending/synthesis?
-free nucleotides air up with exposed bases
-tag polymerase joins up backbone in 5’ to 3’ direction
-forming phosphodiester bonds
What temperature does extending/synthesis occur at?
72 c
