Genetics: Alleles and Traits

This podcast explores advanced genetic concepts beyond Mendelian genetics, including co-dominance, incomplete dominance, multiple alleles, pleiotropy, and polygenic traits. It begins with a review of Mendel's principles of dominance and segregation, then delves into examples like carnations and cows for co-dominance, rabbit fur for multiple alleles, PKU for pleiotropy, and skin and eye color for polygenic traits.

What is the principle of dominance as described by Mendel?

• A recessive allele masks the effect of a dominant allele.

• A gene that is always expressed in the phenotype.

• A gene that is never expressed in the phenotype.

• A dominant allele masks the effect of a recessive allele.

In the context of incomplete dominance, what is the expected phenotype when a red carnation is crossed with a white carnation?

• Red carnation

• White carnation

• Pink carnation

• Spotted carnation

Which of the following best describes co-dominance?

• One allele is completely dominant over the other.

• Both alleles contribute equally to the phenotype.

• Neither allele is expressed in the phenotype.

• The phenotype is a blend of both alleles.

What is a characteristic of multiple alleles?

• All alleles are expressed equally in the phenotype.

• A gene can have more than two alleles in a population.

• Only two alleles exist for each gene in a population.

• An individual can have more than two alleles for a gene.

How do multiple alleles contribute to genetic diversity?

• By ensuring all individuals have the same phenotype.

• By allowing for a wide range of phenotypes in a population.

• By limiting the number of possible phenotypes.

• By reducing the number of alleles in a population.

What is pleiotropy?

• A single gene affecting multiple traits.

• Multiple genes affecting a single trait.

• A gene that does not affect any trait.

• A gene that only affects one trait.

Which disorder is used as an example of pleiotropy in the podcast?

• Huntington's disease

• Phenylketonuria (PKU)

• Sickle cell anemia

• Cystic fibrosis

What defines a polygenic trait?

• A trait controlled by a single gene.

• A trait controlled by multiple genes.

• A trait that is only influenced by environmental factors.

• A trait that is not influenced by genes.

Which of the following is an example of a polygenic trait?

• Blood type

• Eye color

• Widow's peak

• Tongue rolling

How do polygenic traits contribute to variation in a population?

• By reducing genetic diversity.

• By limiting the number of possible phenotypes.

• By creating a wide range of phenotypes.

• By ensuring all individuals have the same phenotype.