2/15 - Pedigree - Deducing Genotypes

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 autosomal dominant inheritance mean?

Back

Autosomal dominant inheritance means that only one copy of a dominant allele is needed for an individual to express the trait.

Front

What are the possible genotypes for an individual with an autosomal dominant trait?

Back

The possible genotypes are either homozygous dominant (AA) or heterozygous (Aa).

Front

What does autosomal recessive inheritance mean?

Back

Autosomal recessive inheritance means that two copies of a recessive allele are needed for an individual to express the trait.

Front

What is the probability of two carriers (Aa) having a child with an autosomal recessive trait?

Back

The probability is 25%.

Front

What is X-linked inheritance?

Back

X-linked inheritance refers to genes located on the X chromosome, where males (XY) are more likely to express recessive traits than females (XX).

Front

What does X-linked recessive inheritance mean?

Back

X-linked recessive inheritance means that a recessive allele on the X chromosome can cause the trait to be expressed in males and in females who are homozygous for the recessive allele.

Front

What is the genotype of a female carrier for an X-linked recessive trait?

Back

The genotype of a female carrier is X^A X^a.

Front

What is the genotype of a male with an X-linked dominant trait?

Back

The genotype of a male with an X-linked dominant trait is X^A Y.

Front

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

Back

If a trait is X-linked dominant, only one copy of the dominant allele on the X chromosome is needed for the trait to be expressed.