Lecture 9/30 - E2 Flashcards
(18 cards)
What is the Manhattan Plot?
A plot used to show where SNIPs are above a certain threshold to provide evidence for being associated with disease genes in this region
________ ______ ______ generate individual genetic profiles using labratory analysis of carefully selected markers followed by statistical evaluation.
Contemporary Forensic Methods
_____ _____ ____ and _____ _____ _____ _____ contain repeateing DNA sequences less than 10bp or more than 10bp long can be used for genomic analysis.
Short tandem repeats (STRs)
Variable number tandem repeats (VNTRs)
Are STRs or VNTRs used in forensic analysis?
STRs because of their broad representation
What is the Combined DNA Index System (CODIS)?
The FBI’s extensive analysis culminating in selection of 13 independently assorting human STR markers
What is the CODIS Marker Criteria?
- Have known chromosome location
- Have multiple alleles (8-16) in the population examined
- Carry alleles that can be accurately amplified by PCR
- Have distinct PCR product lengths that distinguish alleles from one another
What is capillary (tube) gel electrophoresis and why is it used?
Used to automate the analysis of PCR-amplified STR fragments
Uses a florescent dye-tagged nucleotide that is incorporated during each CODIS marker PCR and the resultant DNA band can be detected
When given the DNA profile results for the CODIS STRs, what does the horizontal axis indicate?
Fragment length
When given the DNA profile results for the CODIS STRs, what do the numbers above the peaks represent?
Repeat length
When given the DNA profile results for the CODIS STRs, what do double peaks indicate?
Heterozygous genotype
When given the DNA profile results for the CODIS STRs, what do single peaks indicate?
Homozygous genotype
When using CODIS for forensic analysis, what does law enforcement usually require?
A minimum of 13 CODIS markers to be scored with at least 10 providing useful information
How are STR allele frequencies used?
To determine the probability that another person selected at random has the same genotype
What term is defined as the number of copies of the allele in a population divided by the sum of all alleles in that population?
Allele frequency
How do you calculated the probability (P) of a heterozygous individual having both alleles at a single locus?
P = 2pq
p and q are frequencies
p is from mom while q is from dad, but it can also be reversed. Therfore, multiple by 2 as well.
What is the probability (P) of a genotype in a homozygous individual with an allele frequency p?
P = p^2
How do you calculate the joint probability that a genotype will have a certain distribution at random?
Multiply all the genotype frequencies
What are some of the issues related to crime scene DNA analysis?
DNA does not necessarily mean that the accused individual is guilty of any crime, only that the person was likely present
