IMED2004 Final: IMED2004_ Notes Codominance
Document Summary
Heterozygous phenotype is not intermediate between those of the homozygotes. But simultaneously expresses phenotypes of both homozygotes. In abo blood group, the 3 major alleles are i, ia & ib, These determine presence of sugar molecules on rbc. A person has 2 alleles which interact to give the 4 blood groups (phenotypes) Create a greater variety of genotypes & phenotypes. Some loci have more than 2 alleles present. Antigens = short ch2o chains on rbc membrane. I. e. a result of interactions between genes at the same locus. Dominance doesn"t alter how genes are inherited. But does influence the way genes are expressed as a phenotype. So dominance"s allelic interaction is between the products of the genes. Classification of dominance depends on the level at which the phenotype is examined. Many of a person"s characteristics are determined. By an interaction between genes & the environment. Which can play a role in some genetic disorders. Several genes work together to determine height.
