DNA 2 - MT2 - Part 1 Flashcards
Polymorphism
Is an inherited character from which different traits are present in a population
What are 3 examples of polymorphisms?
- Mouse fur colour
- Human eye colour
- Human blood type
Where is DNA polymorphism located?
On a specific chromosome that has appreciable variation in a population
What are genes and the expression of genes in an organism basic to? (2)
- Morphology
2. Functioning of the organism
What can DNA sequence be irrelevant in determining?
The organisms observable properties
What do many polymorphisms have nothing to do with?
Determining the characteristics of the organism that carry from one individual to another
What are 3 types of DNA polymorphism?
- SNP
- VNTRs
- STR
SNP
Single nucleotide polymorphism
Single nucleotide polymorphism
Is a site where different base pairs are found in different individuals
- the sight might be part of a gene or might be outside the gene sequences
VNTRs
Variable number of tandem repeats
STR
Short tandem repeats
What are VNTR regions?
Sites in the genome where a short DNA sequence (15-100bps long) is repeated over a distance of 1000-20,000 bp
What are STR regions?
Is similar to VNTR region, except that the repeated sequence is 2-9bp long and is repeated 7-40 times
- its a lot shorter
- the repeat number is polymorphic but the flanking sequence are not
What does each STR region have? (2)
- An unique name
2. Chromosome location
What do no 2 people have the same of?
Chromosome repeats
- expect maybe identical twins
What are 6 sources of DNA?
- Blood
- Semen
- Hair
- Bits of tissue
- Saliva
- bones
When should you use VNTR loci?
When there is a lot of source tissue and a lot of DNA is available
- DNA needs to be largely intact
- not used very much anymore
Southern blot
Is a method used in molecular biology for detection of a specific DNA sequence in DNA samples
What is souther blot a combination of? (2)
- Electrophoresis
- Hybridization
- combines transfer of electrophoresis separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization
What are the 6 steps in southern blotting?
- DNA digestion
- Gel electrophoresis
- Blotting
- Probe labeling
- Hybridization and washing
- Detection
What can restriction enzymes do?
They can cut DNA at specific sequences
- different restriction enzymes recognize and cut different sequences
- wanted the ability to move genes around
When do you use STR loci?
When a small amount of DNA is available
- the procedure involves PCR amplification of the STR region, using flanking sequences as primers and direct detection of the amplified DNA on a gel
What does 1 peak in the STR loci mean?
Homozygous
What does 2 peaks in the STR loci mean?
Heterozygous
How can you calculate the probability of a DNA match between 2 unrelated people?
Hardy Weinberg equilibrium equation
What does the Hardy Weinberg equilibrium equation describe?
What happens in one generation (with no natural selection, immigration or reproduction, etc)
- the frequencies of the genotypes in progeny can be calculated by the frequencies of the alleles in the parents generation
What 5 things can go wrong with DNA evidence?
- The DNA might be too degraded to use
- DNA from someone who is not at the crime scene
- Contaminating DNA might have been accidentally introduced during testing
- PCR is very sensitive - DNA evidence might have been planted or fabricated to fame someone who was innocent or avert suspicion from someone who is guilty
- Two of more experts might draw different conclusions from the same evidence
What enzyme digests DNA? (2)
- Nucleases
- as long as the cells have not been dried out
- they are naturally occurring enzymes
- no recognition sequence - Micro-organisms
What is a very good source for DNA? (2)
- Dried blood
- it wont degrade very fast and can last a long time - Neanderthal toe bone
What sequences can only be amplified?
Intact sequences
