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

What does it mean if a disorder is recessive?

Back

A recessive disorder means that an individual must have two copies of the recessive allele (hh) to express the disorder.

Front

How many alleles does a person carry for a trait?

Back

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

Front

What is a carrier in genetics?

Back

A carrier is an individual who has one copy of a recessive allele and one copy of a dominant allele (Hh) but does not express the recessive trait.

Front

What does homozygous mean?

Back

Homozygous refers to having two identical alleles for a particular gene (e.g., HH or hh).

Front

What does heterozygous mean?

Back

Heterozygous refers to having two different alleles for a particular gene (e.g., Hh).

Front

What is the significance of dominant alleles?

Back

Dominant alleles can mask the effect of recessive alleles, meaning that only one copy of a dominant allele is needed for the trait to be expressed.

Front

In a pedigree, how can you identify a carrier?

Back

A carrier can often be identified if they have offspring that express a recessive trait, while they do not express it themselves.

Front

What is the purpose of a pedigree chart?

Back

The purpose of a pedigree chart is to track the inheritance of traits and genetic disorders through generations of a family.

Front

What does it mean if an individual is homozygous dominant?

Back

An individual is homozygous dominant if they have two copies of the dominant allele (e.g., HH) and will express the dominant trait.