Multiple Alleles

Multiple Alleles Remember: Chromosomes occur in pairs. (homologous pairs)   the different alleles of a gene occupy the same positions on each chromosome

Multiple Alleles So far each gene we have discussed has been made of two possible alleles.   Ex. B = blue b= yellow R = red r = white

Multiple Alleles However, it is possible to have several different allele possibilities for one gene.   Multiple alleles is when there are more than two allele possibilities for a gene.

The gene for blood type has 3 possible alleles. Multiple Alleles In traits with multiple alleles, each individual can carry any two of the several possible alleles.   Ex. BLOOD TYPE The gene for blood type has 3 possible alleles. A, B, or O

Blood Type In this case both A and B are dominant to O (recessive). A and B are codominant (both expressed)   So... there are four human blood types AA, AO A blood type BB ,BO B blood type AB AB blood type or OO O blood type

Blood Type

Blood Type Practice Problems: 1. A mother is AB and a father is O. Draw the punnett square. A B O   What is the probability their offspring will have A type blood? Can they have an offspring with O blood?

Blood Type 2. A mother is AO and a father is BB. Draw the punnett square.   What is the probability their offspring will have B type blood? Can they have an offspring with O blood?

Blood Type 3. If a child has AB blood which of the following could NOT be the parents? a) OO, AB b) AO, BB c) BB, AA d) AO,BO

Blood Type