Pedigree Practice

Front

What is a pedigree chart?

Back

A pedigree chart is a diagram that shows the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors, used to analyze the inheritance of traits.

Front

What does it mean if a trait is X-linked recessive?

Back

An X-linked recessive trait is one that is carried on the X chromosome and typically manifests in males, as they have only one X chromosome. Females can be carriers without showing the trait.

Front

How can you identify a dominant trait in a pedigree?

Back

A dominant trait typically appears in every generation of a pedigree, meaning that at least one parent must have the trait for the offspring to inherit it.

Front

What does the genotype X^A X^a represent?

Back

The genotype X^A X^a represents a female who is a carrier for an X-linked recessive trait, where X^A is the dominant allele and X^a is the recessive allele.

Front

How many females in a pedigree can have a recessive trait?

Back

In a pedigree, females can have a recessive trait if they inherit two copies of the recessive allele (one from each parent).

Front

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

Back

A skipped generation in a pedigree often indicates that the trait is recessive, as it may not appear in every generation.

Front

What does it mean if a male has the genotype X^a Y?

Back

A male with the genotype X^a Y is affected by an X-linked recessive trait, as he has only one X chromosome carrying the recessive allele.

Front

How do you determine the number of individuals in a specific generation of a pedigree?

Back

To determine the number of individuals in a specific generation of a pedigree, count the symbols (circles for females and squares for males) in that generation.

Front

What is the difference between a carrier and an affected individual?

Back

A carrier has one copy of a recessive allele and does not show the trait, while an affected individual has two copies of the recessive allele and expresses the trait.

Front

What does it mean if a trait is autosomal dominant?

Back

An autosomal dominant trait is one that can be expressed in individuals who have just one copy of the dominant allele, appearing in every generation.