DNA Profiling Field Trip 411

Basics Nucleus contains 23 pairs of chromosomes. Each chromosome contains alleles or versions of traits (ex: eye color, hair color) Sequences of these alleles on each chromosome are polymorphic (many forms) Polymorphic sequences provide information on paternity, ID and genetic testing

Alec Jeffries First researcher to realize DNA polymorphisms can establish human identity. Discovered in 1984

Repeat Polymorphisms One class of polymorphism results from repeated copies of a DNA sequence that lie directly next to eachother Each sequence can have tens of different alleles Highly heterozygous (1 allele from each parents)

Common Polymorphisms STR Short tandem repeats VNTR Variable number of tandem repeats

Other Repeats Di and tri nucleotide repeats cause mutations found in Huntington disease, Alzheimer Disease and fragile X syndrome

FBI FBI uses 13 marker panel of STR’s to establish an individuals fingerprint Because of the number of independently inherited polymorphisms the probability of even the most common combination is tens of billions DNA testing can identify every person alive FBI index contains over 5 million profiles and has used over 45,000 to aid in almost 47,000 investigations

Our Experiment We will look at a VNTR on chromosome 1 called D1S80 Has a repeat unit of 16 base pairs Most individuals have between 14 and 40 copies of this repeat on each copy of chromosome 1

PCR Polymerase chain reaction PCR is used to determine the number of repeated DNA sequences within a variable region of chromosome 1 Each sequence will be compared to the group after being loaded into the wells of a DNA chip.

Electrophoresis Separates DNA fragments according to size Gel electrophoresis will be used to analyze the PCR products

Lab Expectations Take a saline solution into your mouth, swish and expel into a paper cup Use a micropipet to transfer 1ml of liquid into another tube Centrifuge for 1 minute Pour off excess Withdraw sample and add to a tube containing Chelex and shake well Boil sample for 10 minutes then cool Centrifuge for 1 minute Micropipet excess into a clean 1.5 ml tuve

DNA Amplification Micropipet buffer mix into a PCR tube Micropipet DNA from part 1 and centrifuge Label your tubes Store on ice

Chip Electrophoresis Micropipet PCR sample into DNA chip well Place the tip of the pipet directly against the bottom of the well to avoid bubbles Place DNA chip into the Bioanalyzer