Diagram of inheritance features showing mother’s and father’s genomes, illustrating genotype influence on traits like height, skin color, eye color, hair color, and genetic disorders.

Illustration of genotype effects in inheritance, showing parental genome contributions to physical traits and genetic conditions.

Genotype

Category: General Biology Date: November 12, 2024

Definition of Genotype

A genotype is the genetic makeup of an organism, consisting of the specific alleles inherited from both parents. It determines many traits and can influence an organism’s phenotype.

Homozygous vs. Heterozygous

Homozygous and heterozygous genotypes describe different combinations of genes, or alleles, that a person inherits from their parents. Alleles are different forms of a gene, and each person gets one allele from each parent.

In a homozygous genotype, both alleles are the same. For example, if both alleles for a gene are “A” or both are “a,” the person is homozygous for that gene. Being homozygous means the person has two identical alleles for a particular trait, which could result in showing that specific trait more strongly.

In a heterozygous genotype, the alleles are different. For example, one allele could be “A” and the other “a.” Being heterozygous means the person has one of each type of allele for a trait. Often, one allele is dominant and the other is recessive. This means the dominant allele will determine the trait that shows up.

So, a homozygous genotype has matching alleles, while a heterozygous genotype has one of each. These combinations help determine how traits are passed down and what traits we show.

Examples of Genotypes

Genotypes are combinations of genes that determine specific traits. These combinations are made up of two alleles, one from each parent. Let’s look at a few examples to understand how genotypes work.

For example, let’s say the gene for eye color has two alleles: “B” for brown eyes and “b” for blue eyes. If someone has a BB genotype, they received a “B” allele from each parent. This would likely give them brown eyes because “B” is dominant. If their genotype is Bb, they also have brown eyes because the “B” allele is still dominant over “b.”

On the other hand, if a person has a bb genotype, they received a “b” allele from each parent. With no dominant “B” allele, this genotype would likely give them blue eyes.

Another example is the gene for dimples. If “D” is the allele for having dimples and “d” is for no dimples, then a DD genotype or Dd genotype would mean the person has dimples. Only a dd genotype would result in no dimples.

So, genotypes like BB, Bb, and bb show different combinations of alleles. These combinations determine traits like eye color, dimples, and many other characteristics we inherit.