Inheritance through Multiple Alleles & Multiple Genes

Some human traits are controlled by a single gene with only two alleles. Others are determined by a single gene that has multiple alleles. Still others are governed by the interaction of two or more genes, which may not even be located on the same chromosome.

Polygenic traits are controlled by two or moregenes(usually by many different genes) at differentlocationson differentchromosomes. These traits DO NOT follow the inheritance patterns of Mendel. Many traits in humans are polygenic, including eye color, hair color, skin color, and height. This is why we see so much variation in these traits. Scientists are still learning a great deal about these traits in the human body, as well as in other living organisms.

Multiple Alleles

1.  Complete a punnett square to show the results of a cross between a man who is heterozygous type B and a woman who is heterozygous type A. Give the phenotype and genotype results.

2.  Complete a punnett square to show the results of a cross between a man who is type AB and a woman who is type O. Give the phenotype and genotype results.

3.  The blood type of an individual is determined by ____ alleles, but _____ alleles exist in the whole population.

4.  There are ______blood types among human beings.

Polygenic Traits

In Snarlymonsters, the number of teeth is polygenic. The recessive condition (aabbcc) results in a toothless Snarlymonster, and the dominant condition (AABBCC) results in a Snarlymonster with 6 teeth. There are 5 other possible variations.

How many teeth would a AaBbCc Snarlymonster have? ______

If the mom in the above cross was AABBCC, what what most likely dad’s genotype? ______

What would be a genotype for a 2-toothed Snarlymonster? ______