Alleles and Genes

What is the chemical compound known as PTC?

• A type of sugar molecule

• A protein found in taste buds

• Phenylthiocarbamide

• A common food additive

Why is PTC paper commonly used in genetics classes?

• It helps students identify different types of paper.

• It demonstrates how taste buds function.

• The ability to taste PTC is a genetically determined trait.

• It is a safe and inexpensive chemical for experiments.

What is the definition of a gene in the context of genetics?

• A type of protein that builds cells.

• A condensed unit of DNA and protein.

• A portion of DNA that codes for a characteristic or trait.

• A structure found only in taste buds.

Which of the following best describes an allele?

• A specific location on a chromosome.

• A variant or form of a gene.

• A type of chromosome inherited from a parent.

• A protein that determines taste sensitivity.

What determines whether an individual can taste PTC or not?

• The type of food they eat.

• The two alleles inherited for the PTC taste sensitivity gene.

• The number of taste buds on their tongue.

• Their exposure to PTC during childhood.

In Mendelian inheritance, what does a capital letter typically represent for an allele, and when is its associated trait expressed?

• A recessive allele; expressed only if two copies are present.

• A dominant allele; expressed if at least one copy is present.

• A recessive allele; expressed if at least one copy is present.

• A dominant allele; expressed only if two copies are present.

Which genotypes would result in an individual being a PTC taster, given that PTC tasting is a dominant trait?

• Only TT

• Only tt

• TT and Tt

• Tt and tt

If a child is a non-PTC taster (genotype tt), but both of their parents are PTC tasters, what must be the genotypes of the parents?

• Both parents are TT.

• One parent is TT and the other is Tt.

• Both parents are Tt.

• One parent is Tt and the other is tt.