DNA Profiling
Summary of DNA Profiling and the cycle used to create a profile
- Created by: Laura Stally
- Created on: 09-01-13 11:06
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- DNA Profiling
- Why?
- Screen for a genetic condition
- Measuring genetic diversity
- Studying Evolutionary relationships
- How?
- STRs occur at the same loci on both homologous chromosomes
- Looks at the introns. WIthin introns STR are found
- Number of STRs vary between individuals
- Obtaining the DNA
- Cells from cheek swap, blood, tissue, bone marrow
- Sample broken down in detergent
- DNA extracted from cell debris by filtering or certrifuging
- Protease enzymes added to remove proteins
- Cold ethanol to precipitate out the DNA
- Creating the Fragments
- Restriction enzymes / endonucleases wil cut DNA at specific bases
- Found naturally in bacteria where they cut up viral RNA
- Same restriction enzyme is used to cut two identical DNA samples, identical STR fragments will be created
- Restriction enzymes / endonucleases wil cut DNA at specific bases
- Polymerase Chain Reaction
- DNA is copied numerous times
- DNA Primers = short sections of DNA complementary to the DNA adjacent to the STR
- DNA primers, nucleotides, DNA polymerase added to reaction tube
- Gel electrophreisis - Separating Strand
- Connected to electrodes, negatively charged DNA travels to the positive electrode
- DNA fragments add to agrose gell which is submerged into buffer solution
- Visualising the Fragments
- Technique called southern blotting, nirtocellulose membrane placed directly on the gel and a wad of dry paper is placed on top
- Single band occurs on a profile when a persons maternal and paternal chromosomes have same number of repeats at a particular locus
- Why?
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