Lect 19 - extensions of mendelian genetics

Flashcards on extensions of Mendelian genetics, including dihybrid crosses, probability, polymorphism, incomplete dominance, co-dominance, polygenic traits, and environmental effects on phenotype.

What is a dihybrid cross?

A genetic cross between two individuals that examines the inheritance of two different traits, each controlled by a different gene.

What is the probability of getting ssyy from SsYy x SsYy?

0.0625

In determining the probability of getting ssyy from SsYy x SsYy, what are the probabilities of each parent supplying 's' and 'y'?

Parent 1 supplies s = 0.5, Parent 2 supplies s = 0.5, Parent 1 supplies y = 0.5, Parent 2 supplies y = 0.5

What rule applies for independent events in genetics?

Product rule

What does polymorphic mean in genetics?

One gene can have many alleles, but each individual can only have two alleles, one on each homologous chromosome.

What is incomplete dominance?

When F1 has an intermediate phenotype.

What observation in the F2 generation rejects blending inheritance?

The appearance of parental phenotypes in F2 generations after incomplete dominance.

What is co-dominance?

When both parental phenotypes are present in F1 (e.g., blood antigen system: AB blood).

What are polygenic traits?

Phenotype controlled by many genes that have an additive effect; characters appear continuous or quantitative.

What distribution is typical of a polygenic trait in a population?

A normal distribution.

How does the number of genes involved affect the number of phenotypic classes in polygenic traits?

The more genes involved, the higher the number of phenotypic classes.

How does the environment affect phenotype?

Environment acts as a phenotype (e.g., hydrangea is pink in alkaline soils but blue in acidic soils).

How does the environment influence the expression of phenotypes?

Environment smooths differences among phenotypes