Pedigrees

Front

What is a pedigree?

Back

A pedigree is a diagram that shows the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors.

Front

How many alleles does a person carry for a trait?

Back

A person carries 2 alleles for a trait, one inherited from each parent.

Front

What does a filled circle represent in a pedigree chart?

Back

A filled circle represents a female who expresses the trait being studied.

Front

What does a filled square represent in a pedigree chart?

Back

A filled square represents a male who expresses the trait being studied.

Front

What is the purpose of a Punnett square?

Back

A Punnett square is used to predict the genotypes of offspring from a cross between two parents.

Front

What does it mean if an individual is heterozygous for a trait?

Back

An individual is heterozygous for a trait if they have two different alleles for that trait (e.g., Rr).

Front

What does it mean if an individual is homozygous for a trait?

Back

An individual is homozygous for a trait if they have two identical alleles for that trait (e.g., RR or rr).

Front

How can you determine the number of generations in a pedigree?

Back

Count the horizontal rows in the pedigree chart; each row represents a generation.

Front

What is the significance of the parental generation in a pedigree?

Back

The parental generation is the first generation in a pedigree, from which all subsequent generations are derived.

Front

What is a recessive trait?

Back

A recessive trait is one that is expressed only when an individual has two copies of the recessive allele (e.g., rr).