DNA profiling using PCR student notes

1. DNA Profiling using PCR
Uses these properties of DNA:
DNA contains exons and introns (non-coding areas)
Non-coding DNA has repetitive sequences
Some are short (2 – 6 base pairs ) microsatellites or STRs that can
repeat up to 100 times
Different people have different length STRs
Some STRs are more variable (polymorphic) between people than
others
Polymorphisms are shared by 5 – 20% of individuals but targeting
multiple known STRs gives unique combinations. The more loci,
the more discrimination.
NZ targets 10 STR sites (the most variable possible)
STRs are allelic – you may inherit different ones from each parent
(can be homozygous and heterozugous)
Homozygous STRs will not separate out with gel electrophoresis
because they will be the same length; heterozygous STRs will
make separate bands.