5.2 Variations of Heredity Pages

Incomplete Dominance Occurs when neither allele dominates the other and both have an influence on the individual. Incomplete dominance results in partial expression of both traits.

Incomplete dominance in impatiens

Incomplete Dominance in Animals Rex rabbit (short fur)crossed with angora rabbit (long fur)

Punnett Square

Codominance Occurs when both alleles are expressed fully to produce offspring with a third phenotype.

Codominance in short horn cattle

Blood types There are 3 alleles for bloodtype: I A, I B, i

Blood

Alleles Each allele codes for a different enzyme that places different types of sugars on the surface of a red blood cell.

There are four types of blood Type A Type B Type AB Type O

Genotypes and Phenotypes I A I A blood type A I B I B blood type B I A I B blood type AB I A iblood type A I B i blood type B iiblood type O

Antigens Type A blood has anti-B antigens. If a person with A-type blood receives B-type blood or AB-type blood, it will clot.

Blood types

Blood type O The universal donor because people with every blood type can receive O-type blood without a danger of it clotting.

Blood Type AB The universal recipient because people with AB blood can receive any type of blood