Multiple Alleles and Blood Groups
Different forms of the same gene.
When more than two alleles control a trait these are known as multiple alleles.
The alleles controlling blood groups are a well known example of multiple alleles.
There are three alleles for blood groups within the human population
A, B and o. (A and B are equally dominant and o is recessive).
Every person will have just two of these three alleles. So the possible combinations are as follows
A man whose blood group
is A marries a woman with blood group O. Show the possible genotypes and
phenotypes of their children.
(Remember: The man can have the genotype AA or possibly Ao. The woman can only be oo
Therefore we must do out two crosses to show the possible offspring.)
|Parents:||Group A||X||Group O|
|F1 Genotype:||All Ao|
|Phenotype:||All Group A|
|Parents:||Group A||Group O|
|Phenotype:||Group A||Group O|
|Following the same
layout try the following cross:
Parents: Group AB Group O
Show how two parents who both are Group A could have a child that is Group O