An animal needs two recessive alleles to display the recessive phenotype. In traits with complete dominance, like coat color, an animal needs only one of the dominant alleles to display the dominant phenotype.An individual with two different alleles of a gene is heterozygous. An individual with the same two alleles for a gene is homozygous.All animals have two copies of each gene and pass along one copy to their offspring.Some tips to remember when using a Punnett square: To use a Punnett square, you should know the genes involved with the trait, the genotypes of the parents, and whether certain alleles (variations of the same gene) are dominant, recessive, or somewhere in between. A Punnett square is a handy tool to predict expected progeny outcomes of simply-inherited traits from a specific mating. Coat color, horned/polled status, and many genetic conditions fall under the category of simply-inherited traits.

The alleles that offspring receives from its parents can determine what happens to its genetic line for generations to come.Simply-inherited traits are those where one or just a few genes control the phenotype. They can also protect offspring from gene mutation and possibly harmful genetic disorders.

Their offspring range in eyesight ability (ee and Ee).Īs you can see, heterozygous traits allow for greater genetic variation.

One parent has poor eyesight (ee), but the other has a dominant allele for strong eyesight (Ee).

Two flowers with ten petals but different genotypes (PP and Pp) produce seeds for flowers with the dominant allele for ten petals and flowers with the recessive allele for nine petals.

The child receives one recessive allele from each parent (dd) and neither carries nor exhibits the genetic disorder.

One parent is a carrier for a genetic mutation on a dominant allele (Dd), but the other parent only has recessive alleles for that chromosome (dd).

Some puppies have shorter legs from their mother’s recessive alleles, while others are very tall because of their father’s dominant alleles.

A litter of puppies with a Golden Retriever mother and a Great Dane father exhibit a variety of traits.

One child has type AB (AB) blood but their sibling has type A blood (Ao) because they received one dominant A allele and one recessive O allele.

One parent has two dominant alleles for type A (AA) blood, and the other parent has one dominant allele (B) and one recessive allele (o) for type B (Bo) blood.

The offspring has black hair (Bb) because they exhibit the dominant gene only.

A parent provides the dominant allele for black hair (B), and the other parent provides the recessive allele for blonde hair (b).

Here are some examples of how offspring can exhibit heterozygous traits: That’s why siblings with the same parents sometimes look very different from each other: they received different combinations of genes. Offspring who receive a dominant allele from one parent and a recessive allele from the other parent will exhibit heterozygous traits. Genetics get a bit more complicated when it comes to heterozygous, or “different genetic” traits. Check out more examples of homozygous traits with an educational article. However, if a parent has homozygous traits, it’s more likely that their offspring will resemble them. Homozygous traits don’t always mean that offspring look exactly like their parents.

Both parents pass on the recessive trait for poor eyesight (e), so the child will also have poor eyesight (ee).

Flowers that each have ten petals create seeds that will sprout flowers with ten petals each.

Parents who are carriers of genetic mutations on dominant alleles (Dd) have a stronger likelihood of having a child that exhibits a genetic disorder (DD).

A litter of purebred Golden Retriever puppies receive the same genes for leg length and fur color from each of their purebred parents.

Parents of a child with recessive type O (oo) blood each have type O blood.

Both parents have two dominant alleles for black hair (B), so their offspring receive only dominant alleles (BB) and have black hair.

You may see homozygous traits in the following situations: These alleles can either be dominant or recessive. Homozygous means “same genes received during the zygote period of development.” An individual with homozygous traits received one copy of each allele from each parent.

Examples of dominant traits