Multiple Alleles Genetics Unit Biology 30 Mrs. S. Pipke-Painchaud Multiple Alleles • have 3 or more alleles for the same gene (or at a single locus) • In Other Words – there are 3 or more alleles that create the different traits. • at most one individual will have 2 alleles or 1 pair (unit factors exist in pairs.) • in a species, however, many alternative forms exist Example – ABO Blood Group • this deals with the presence of antigens – These are like labels/ name tags on the blood cells. • Each individual has 1 of 4 phenotypes – Type A – Type B – Type AB – Type O – What are you? The Info You Need To Know • Gene designated is I (isoagglutinogen) – I = A antigen – I = B antigen – i = no antigen • IA IB and are both codominant • IA and IB are both dominant to I (type O) Genotype IAIA IAi IBIB IBi IAIB ii Antigen A A B B AB Neither Phenotype A A B B AB O • http://learn.genetics.utah.edu/units/basics/blood/types.cfm Website Resoures • Nobel Prize – Blood Typing Website: – http://nobelprize.org/educational_games/medicine/landsteiner/rea dmore.html – View for animations and background info on blood types. • Wikipedia – Blood Types – http://en.wikipedia.org/wiki/Blood_type – Contains a chart of blood types by nation. • Maps of the Distribution of Human Blood Types all over the World. – http://anthro.palomar.edu/vary/vary_3.htm • Sickle Cell Anemia Example: – http://www.astrographics.com/GalleryPrintsIndex/GP2146.html Did You Know? • B is the rarest allele. • 16% of the population have it. – Distribution of Blood Types • http://anthro.palomar.edu/vary/vary_3.htm http://www.uwosh.edu/med_tech/teachin g/ElementaryHemeWeb/LEARN%20AB http://www.faqs.org/health/i • Wikipedia: http://en.wikipedia.org/wiki/Image:ABO_blood_type.svg Practice • If a person with Type A (Heterozygous) blood married and had children with a person who has Type B (Heterozygous) blood, what would the genotypic and phenotypic ratios be? – I Ai X I Bi IA i IB IAIB IBi i IAi ii Genotypic Ratio: 1 IAIB : 1 IAi: 1 IBi: 1 ii Phenotypic Ratio: 1 AB: 1 A: 1 B: 1 O Practice • If you crossed a person with type 0 with heterozygous type B, what would the phenotypic ratio be? – ii X IBi – Phenotypic Ratio: • 1B:1O i i IB IBi IBi i ii ii Website Resoures • Nobel Prize – Blood Typing Website: – http://nobelprize.org/educational_games/medicine/lan dsteiner/readmore.html – View for animations and background info on blood types.