Punnett Squares

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 homozygous mean?

Back

Homozygous refers to having two identical alleles for a particular gene, such as AA or aa.

Front

What does heterozygous mean?

Back

Heterozygous refers to having two different alleles for a particular gene, such as Aa.

Front

What is the phenotype?

Back

The phenotype is the observable physical or biochemical characteristics of an organism, determined by its genotype.

Front

What is the genotype?

Back

The genotype is the genetic makeup of an organism, represented by the alleles it possesses.

Front

What is the difference between dominant and recessive alleles?

Back

Dominant alleles are expressed in the phenotype even if only one copy is present, while recessive alleles are only expressed if two copies are present.

Front

What offspring do you get from crossing a homozygous dominant (WW) with a homozygous recessive (ww)?

Back

All offspring will be heterozygous (Ww) and will express the dominant phenotype.

Front

What is the expected genotypic ratio from a cross between two heterozygous parents (Aa x Aa)?

Back

The expected genotypic ratio is 1 AA : 2 Aa : 1 aa.

Front

What is the expected phenotypic ratio from a cross between two heterozygous parents (Aa x Aa)?

Back

The expected phenotypic ratio is 3 dominant : 1 recessive.

Front

What does it mean if an organism is homozygous recessive?

Back

It means the organism has two identical recessive alleles for a trait, such as aa.