Ch 4 Extensions of Mendelian Genetics

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Week 3 Learning Outcomes

• Discuss allelic variants from wild-type to mutated forms and their influence on phenotype from normal function to loss or gain of function.

• Practice solving the genotypic and phenotypic ratios of non-Mendelian traits that show incomplete dominance, codominance (MN blood group), and multiple alleles (ABO blood group).

• Compare the effect of dominant and recessive lethal genes on survival of offspring.

• Practice solving the offspring ratio from two gene pair combinations using the forked-line method.

• Demonstrate how phenotypes influenced by multiple genes as in epistasis modify the normal predicted dihybrid ratio of 9:3:3:1.

• Discuss the usefulness of complementation.

• Relate single gene with multiple phenotypic effects, pleiotropy.

• Practice solving the ratios produced by sex linked traits crosses.

• Recognize how alterations in phenotypic expression result from differences in genetic background and environmental factors (penetrance and expressivity).