chapter 12 part 2 review

Describe the steps of PCR.

(polymerase chain reaction) denaturation of the template into single strands annealing of the primers to each original strand for new strand synthesis extension of the new DNA strands from the primers

Compare STR to RFLP.

- RFLP analysis requires a fairly large sample of DNA that hasn't been contaminated - STR analysis examines how often base pairs repeat in specific loci, on a DNA strand.

What is RFLP? How are restriction enzymes used?

- RFLP: (restriction fragment length polymorphism) a difference in homologous DNA sequences that can be detected by the presence of fragments of different lengths after digestion of the DNA samples - each enzyme recognizes one or a few target sequences and cuts DNA at or near those sequences

As the number of STRs that are compared increases, what happens to the certainty an individual is guilty?

- the certainty increases - with the help of STR's that increase, they can prove more likely if a person is guilty or not

What is CODIS?

- the combined DNA index system - describes the FBI's program of support for criminal justice DNA databases as well as the software used to run the databases.

What is the purpose of a primer? A polymerase?

- the polymerase can only attach to new DNA nucleotides to an existing strand of nucleotides - they need the primer to lay a foundation for DNA synthesis

How many STRs does CODIS use for comparison?

CODIS uses 13 STR's

What are the steps to electrophoresis?

DNA is added to the gel gel is submerged in tank of buffer solution power pack is attached to the tank and an electrical current is applied after a specific time, the gel would have spread fragments measurements of the fragments can determine DNA length compared to a DNA standard and identifying DNA through matching bands

green river killer

gary ridgeway murdered 48 women in washington after confessing he did not kill any of them. the DNA results came back positive showing that he did kill them all

What is meant by the term loci? alleles?

loci: the physical location of a gene on a chromosome alleles: one of two or more alternative forms of a gene

Why do some DNA fragments travel farther than others?

molecules migrate towards the opposite charge. the smaller the DNA fragment, the faster it moves through the gel. The bigger the fragment, the slower it moves and the shorter the distance through the gel.

What is the difference between the offender index and the forensic index for DNA?

offender index: contains the DNA profiles of those convicted of a crime forensic index: the DNA profile from the evidence is also searched against the state's database of crime scene DNA profiles

What are STRs?

short tandem repeats the area we focus on when we compare DNA

colin pitchfork:

the first person to be convicted of murder based on DNA fingerprinting created by sir alex jeffryes, was also the first to be caught as a result of mass DNA screening (two murder rape charges)

What are the possible outcomes of DNA analysis?

you can find possible suspects you can narrow down your field find family members