Punnett Squares, Pedigrees and Karyotypes

Front

What is a Punnett Square?

Back

A Punnett Square is a diagram used to predict the outcome of a genetic cross by showing the possible combinations of alleles from the parents.

Front

What does it mean for a trait to be dominant?

Back

A dominant trait is one that is expressed in the phenotype even when only one copy of the allele is present.

Front

What does it mean for a trait to be recessive?

Back

A recessive trait is one that is expressed in the phenotype only when two copies of the allele are present.

Front

How do you determine the probability of offspring traits using a Punnett Square?

Back

By filling in the Punnett Square with the alleles from each parent and counting the combinations that result in each phenotype.

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.

Front

What do shaded individuals in a pedigree represent?

Back

Shaded individuals in a pedigree represent individuals that express the trait being studied, which can be either dominant or recessive.

Front

What is a karyotype?

Back

A karyotype is a visual representation of an individual's chromosomes, arranged in pairs and organized by size.

Front

What chromosomal condition is represented by Trisomy 21?

Back

Trisomy 21 is also known as Down Syndrome, a genetic disorder caused by the presence of an extra 21st chromosome.

Front

What is the expected phenotype ratio of offspring from a cross between two heterozygous parents?

Back

The expected phenotype ratio is 3:1, where 3 offspring will express the dominant trait for every 1 offspring that expresses the recessive trait.

Front

If a black sheep (BB) mates with a grey sheep (Bb), what are the expected offspring phenotypes?

Back

The expected offspring phenotypes are 50% black (BB) and 50% grey (Bb).