DNA Flashcards
What is “stutter”?
The bane of the DNA tester’s existence. It’s when a little bit of DNA breaks off during amplification and lands in real DNA’s location. This creates questions about whether the result is stutter or if it is the other guy. Way to tell you have stutter: less than 15%? It’s likely stutter.
What happened in the Sutton case?
The Sutton case was a Texas rape case. He was convicted w/ DNA evidence. The DNA test looked at 5 or 6 loci, and Sutton could not be excluded from being a contributor. Also, the V IDed him a couple days later. Turns out the Houston Crime Lab was run horribly, and Sutton was exonerated by a better DNA test.
What is a locus?
It is a specific spot on a chromosome.
What is an allele?
It is the possible genetic variations at each locus. For each locus, we look at two alleles (one from mom, one from dad).
What is CODIS?
It is the combined DNA index system used to compile people’s genetic info using 13 loci.
How many CODIS loci are there?
13.
What is the product rule?
Multiply the probability of each loci times each other; this gives DNA matches powerful statistical weight. In the example we were shown, random match probability is 1 in 837 trillion (10 to the 17th power).
What is random match probability v. database match probability?
Random match probability is how often you can expect to see a specific profile in another unrelated person chosen at random, while database match probability compares the specific profile to many profiles. Birthday problem: you would expect rmp to be 1/365, but under dmp, it is 1/30(or so b/c you multiply the database’s size times the rmp).
What is mitochondrial DNA?
Newer DNA technology. Looks at your mitochondria’s DNA (mtDNA). Used w/ Richard III’s remains. His mtDNA was matched to two maternally related descendants (1-2% of people share mtDNA).
What is Y-STR?
Male specific STRs (short tandem repeats, which is variable b/w samples). These are present only on the Y chromosome, very useful for mixtures. These were used to ID Sadaam.
What is “spit and acquit”?
In Orange County, if you’re charged w/ a misdemeanor, and you let us swab you, we’ll acquit you.
