DNA Fingerprinting & Forensic Analysis Flashcards
What are the TWO main types of DNA testing?
- Restriction Fragment Length Polymorphism (RFLP)
- Polymerase Chain Reaction (PCR)
What are the THREE steps in PCR?
- Heat
- Anneal
- Extend
What are Microsatallites?
A variable number of repeated nucleotides that occur in specific locations in the genome.
Short Tandem Repeats (STR)
How many STRs have the FBI chosen to test for DNA profiles in their CODIS system?
13
Who developed techniques for extracting DNA from old samples of human tissue?
Jeffries, Gill & Werrett
When is mitochondrial DNA (mDNA) used?
Used for samples that cannot be analysed by RFLP (Restriction Fragment Length Polymorphism) or STR (Short Tandem Repeats), which need nuclear DNA
How many nucleotides and pairs of chromosomes are in the human body?
3 billion nucleotides
23 pairs of chromosomes
What is the percentage of bases that differ from one person to another?
0.1%
Which polymorphic site is cleaved during Restriction Fragment Length Polymorphsim (RFLP)?
A-T
Forms 2 fragments
Which DNA testing technique is used to produce DNA fingerprints?
RFLPs
What do DNA fingerprints produced by PCR detect?
Presence of microsatallites
What are the repeated sequences created by PCR known as?
Short Tandem Repeats (STR)
What are variable tandem repeats?
Repeated sequences of between 1 and 100 bases
Why are STRs unique and what does it provide?
No one has the same STRs and it provides a scientific marker of identity (DNA Fingerprint)
What is the advantage and disadvantage of PCR?
Advantage
Not much DNA is needed
Disadvantage
Very sensitive to foreign DNA contamination
