History of Forensic Biology & DNA

Karl Landsteiner

• He discovers ABO blood typing in 1901

  • blood is differentiates based on the proteins outside the cell

Kidd

• discovered another protein group

Secretor typing

• some people’s ABO blood typing is expressed in other bodily fluids like saliva, semen, or vaginal secretions

Enzyme Testing

• testing for polymorphic enzymes that regulate bodily functions

What does RFLP stand for

Restriction Fragment Length Polymorphism

What is RLFP

• DNA method that utilizes the restriction enzymes that cut DNA into pieces

• REs have specific sequences where they cut, and it is cut into different lengths for each person

• (very labor intensive)

Who discovered RLFP?

Sir Alec Jeffreys

What is the RLFP process?

1. cut DNA with restriction enzymes

2. separate according to size using electrophoresis

3. transfer to stable matrix

4. bind to radioactive hybrid probe (complimentary base string)

5. expose to film

6. develop to visualize

PCR Multiplex

• analysis of multiple STRs in the same reaction location

What are the differences between PCR and RFLP?

PCR Multiplex

• uses small amount of sample

• looking at small pieces if DNA

• PCR makes copies

• works on degraded samples

• faster results

• very discriminating

RFLP

• used radiation

• needed large sample

• looking at big pieces of DNA

• very slow

• not able to automate

• only looking at a few loci

STRs

• Short Tandem Repeats

• set of repeats at the end of DNA strand that don’t code for anything