Exploring Non-Mendelian Genetics: Codominance and Incomplete Dominance

The video explores non-Mendelian genetics, including incomplete dominance, codominance, linked genes, polygenic traits, pleiotropy, sex-linked traits, and non-nuclear inheritance. It explains how these genetic patterns differ from Mendel's laws and their implications for inheritance and phenotypic ratios. The video also highlights the importance of understanding these concepts for the AP Biology exam.

Why are you considered to be more closely related to your mother?

• Because the Y chromosome carries fewer genes than the X chromosome.

• Due to the dominant traits inherited from the mother.

• Due to the mitochondrial DNA inherited exclusively from the mother.

• Because of the larger number of genes inherited from the mother.

What is an example of incomplete dominance?

• Height in humans.

• Eye color in humans.

• Blood type AB resulting from type A and B parents.

• A pink flower resulting from a red and white flower cross.

What distinguishes codominance from incomplete dominance?

• In codominance, the traits blend together to form a new phenotype.

• In codominance, one trait completely masks the other.

• In codominance, both parental phenotypes are visible in the offspring.

• In codominance, a third, unique phenotype is produced.

How does the concept of linked genes challenge Mendel's laws?

• By showing that some alleles are dominant over others.

• By demonstrating that traits can skip generations.

• By indicating that genes on the same chromosome are inherited together.

• By proving that all traits are inherited independently.

What is a polygenic trait?

• A trait that does not follow Mendelian inheritance patterns.

• A trait controlled by multiple genes.

• A trait influenced by environmental factors only.

• A trait controlled by a single gene.

What is pleiotropy?

• The phenomenon where traits are influenced by more than one gene.

• A form of dominance where one allele masks the effect of another.

• The inheritance of traits linked to the sex chromosomes.

• When a gene affects multiple, seemingly unrelated traits.

How do lethal alleles affect phenotypic ratios?

• By having no effect on phenotypic ratios.

• By potentially eliminating one of the expected phenotypes.

• By causing certain phenotypes to appear more frequently.

• By increasing the variability of possible phenotypes.

What makes sex-linked traits unique in terms of inheritance?

• They are always dominant.

• They are controlled by genes on the sex chromosomes.

• They do not follow any recognizable pattern of inheritance.

• They are influenced by environmental factors.

Why is mitochondrial DNA considered a form of non-nuclear inheritance?

• Because it is only passed on by the father.

• Because it is inherited from both parents equally.

• Because it does not influence the phenotype of the offspring.

• Because it is inherited exclusively through the maternal line.

How can geneticists use mitochondrial DNA to trace ancestry?

• By tracking its inheritance through the paternal line.

• By analyzing mutations carried in the mitochondrial DNA.

• By comparing it to the nuclear DNA of the father.

• By observing its influence on the offspring's phenotype.