Detecting Variation
Variation can be at the phenotypic level through to the molecular level.
look for visible differences in the phenotype
chromosome differences eg., length of long arm of Y
immunological markers eg., blood groups
protein gel electrophoresis eg., esterases in Drosophila
SSLPs (Simple sequence length polymorphisms) or VNTR (variable number of tandem repeats)
STR or (short tandem repeats)
Single nucleotide polymorphisms (SNP)
Discontinuous Variation
mid digital hair present or absent
blue or green budgerigar
black or brown dog
Variable regions often in non-coding regions
Minisatellites 15 -100b (eg., tandem repeat of 18 bases) total length from 1-5kb.
Microsatellite short tandem repeats (STR): 2 - 9 bases – can have several alleles according to how many repeats
Single nucleotide polymorphism (SNP) 1 base – can only have two alleles at a locus
VNTR (variable number of tandem repeats) Minisatellites
In non coding regions of the genome
Repeat sequence between 15bp -100bp long
But number of repeats varies from person to person so VNTR can be from 1 - 20kbs in length
Multilocus probe (found in more than one location)
– minisatellites – eg., tandem repeat of 18 bases total length from 1-5kb.
Single locus probe – minisatellites (as above) – microsatellite - short tandem repeats (STR) - 2 - 4 bases
Application Identification
Paternity
Forensic analysis – Crime
Matching after a disaster
