“The capacity to blunder slightly is the real marvel of DNA. Without this special attribute, we would still be anaerobic bacteria and there would be no music.” —Lewis Thomas, Physician, author

Chapter 11 Kendall/Hunt Publishing Company1 DNA Typing/Profiling DNA typing is a method in which DNA is converted into a series of bands that ultimately distinguish each individual from one another.

Chapter 11 DNA Typing / Profiling w 99.9% of DNA found in all humans is the same Able to use the last 0.1% to distinguish identity w First person to do use DNA profiling – Alec Jeffries (1984) Kendall/Hunt Publishing Company2

Chapter 11 Kendall/Hunt Publishing Company3 DNA TYPING “Creating the Fingerprinting”  Two major processes involved: 1.PCR  Polymerase Chain Reaction 2. RFLP  Restriction Fragment Length Polymorphism

Chapter 11 Kendall/Hunt Publishing Company4 PCR Polymerase Chain Reaction PCR  a technique used for making copies of a defined segment of a DNA molecule. This can be valuable when the amount of evidence is minimal. Millions of copies of DNA can be made from a single speck of blood.

Chapter 11 Kendall/Hunt Publishing Company5 PCR The Process The Process 1.Heat the DNA strands, causing the strands to separate (unzip). 2.Cool the mixture and add a primer  a short sequence of base pairs that will add to its complementary sequence on the DNA strand. 3.Finally, add a DNA polymerase and a mixture of free nucleotides to the separated strands. 4.Repeat as needed

Chapter 11 Kendall/Hunt Publishing Company6 PCR DOUBLES Each time the PCR process is completed, the number of DNA strands DOUBLES PCR Virtual Lab

Chapter 11 Kendall/Hunt Publishing Company7 RFLP—Restriction Fragment Length Polymorphisms Restriction enzymes  used to cut DNA into smaller fragments that can then be separated and characterized for identification  Isolate—separate DNA from the cell  Cut—using restriction enzymes to make shorter base strands  Sort—by size using electrophoresis  Analyze—the specific alleles for identification

Chapter 11 Kendall/Hunt Publishing Company8 Electrophoresis  A technique used to separate DNA fragments.  An electrical current is moved through a gel substance causing molecules to sort by size.  The smaller, lighter molecules will move the furthest on the gel.  After developing, the fragments can be visualized for characterization.

Chapter 11 Kendall/Hunt Publishing Company9 DNA Fingerprint Gel

Chapter 11 Kendall/Hunt Publishing Company10 Let's use RFLP technology to determine if Jack is the father of Jill's child named Payle. In this scenario, DNA was extracted from white blood cells from all three individuals and subjected to RFLP analysis. The results are shown below:

Chapter 11 FBI’s CODIS DNA Database  Combined DNA Index System  Used for linking serial crimes and unsolved cases with repeat offenders  Launched October 1998  Links all 50 states  Requires >4 RFLP markers and/or 13 core STR markers