Inheritance of blood types?

Question

I know that there are four blood types: AB, A, B, and O, which are either positive or negative, but I want to know more about these blood types in terms of alleles and inheritance. What are the possible genotypes for blood type? Is blood type inheritance similar to the inheritance of eye colour or is it completely different?

Thank you

Answer 1

Diploid organisms (e.g. humans) have paired homologous chromosomes in their somatic cells, and these contain two copies of each gene. An organism in which the two copies of the gene are identical — that is, have the same allele — is called homozygous for that gene. An organism which has two different alleles of the gene is called heterozygous. Phenotypes (the expressed characteristics) associated with a certain allele can sometimes be dominant or recessive, but often they are neither. A dominant phenotype will be expressed when at least one allele of its associated type is present, whereas a recessive phenotype will only be expressed when both alleles are of its associated type.

However, there are exceptions to the way heterozygotes express themselves in the phenotype. One exception is incomplete dominance (sometimes called blending inheritance) when alleles blend their traits in the phenotype. An example of this would be seen if, when crossing Antirrhinums — flowers with incompletely dominant "red" and "white" alleles for petal color — the resulting offspring had pink petals. Another exception is co-dominance, where both alleles are active and both traits are expressed at the same time; for example, both red and white petals in the same bloom or red and white flowers on the same plant. Codominance is also apparent in human blood types. A person with one "A" blood type allele and one "B" blood type allele would have a blood type of "AB".

Answer 2

Here are some links that address these concepts...

http://en.wikipedia.org/wiki/ABO_blood_g...

http://mistupid.com/health/bloodinherit....

http://www.biology.arizona.edu/Human_Bio...