Difference between homozygous and heterozygous [With Table]

Today’s topic is related to Biology but as you know Biology is one of the crucial parts of our existence, so this topic is too. You might have heard the two words “Homozygous” and “Heterozygous” but don’t know the dissimilarities between these. So we are going to depict the difference between homozygous and heterozygous.

Difference between homozygous and heterozygous

Homozygous Heterozygous
If an individual has the same alleles of a gene from the parents is known as homozygous genetic condition. If an individual has different alleles of a gene from the parents is known as homozygous genetic condition.
Phenotypes can be two types. a) Dominant b) Recessive In heterozygous condition, the phenotype is mostly due to the dominant allele.
Single type gamete. Two different type gametes.
Produce the same traits. They generate different traits.
It is represented as AA or aa. Represented as Aa.
Doesn’t show hybrid vigor. Shows hybrid vigor.
Organisms known as homozygotes. Organisms known as heterozygotes.
Seen in animals reproducing by asexual means. Seen in animals reproducing by sexual means.
Diseases related to homozygous genotypes are fibrosis, sickle cell anemia, phenylketonuria etc. Diseases related to heterozygous genotypes are Huntington’s disease, Marfan’s syndrome, familial hypercholesterolemia etc.

Homozygous Definition

If an individual has the same alleles of a gene from the parents is known as homozygous genetic condition.

Both alleles will be either dominant or recessive according to homozygous chromosomes. The recessive allele is represented by (xx). And the dominant allele is illustrated by (XX).

If both the chromosomes have a dominant gene at similar locus, then the dominant trait can only be revealed into homozygous organisms.

All traits which are held constant will be homozygous if they reproduce organisms by true breeding mechanisms.

Homozygosity can be illustrated at the specific locus where copies of the gene affect a trait present on the two reciprocal homologous chromosomes.

The other name of homozygous cells is homozygotes. So never get confused by it.

Related: Difference between Sin and Sins [with Table].

Significance of Homozygous Cells

You can notice the significance of homozygous chromosomes several times. Genes for eye color where the dominant trait is brown, is seen as BB in homozygous cells.

Homozygous genotypes are the reason for diseases like cystic fibrosis, sickle cell anemia, phenylketonuria.

Some examples of homozygous genotypes :

Eye color

It can be BB where brown is the dominant trait. It can also be bb where brown is not the dominant trait. Other colors like blue, black or green can only be seen when the genotype is bb.


Freckles are known as the skin problem of spots which is caused due to the melanin pigment.

It is also a dominant trait and are controlled by the gene named MC1R gene. People who have freckles have a homozygous genotype which is dominant. This homozygous genotype causes the expression of the dominant allele. But if the genotype is homozygous-recessive, then there will be no freckles.

Related: What’s The Difference Between Glass and Crystals [With Table].

Heterozygous Definition

If an individual has different alleles of a gene from the parents is known as homozygous genetic condition.

Homozygous genotypes are illustrated by both capital or small letters. But heterozygous genotypes contain a capital letter and a small letter. For example, Bb represents the heterozygous genotype for eye color whereas BB or bb represent the homozygous genotypes for eye color.

The two alleles are not the same in heterozygous chromosomes. They must be different.

Trait of genes coded by the dominant allele is expressed in heterozygous chromosomes. This occurs in case of complete dominance.

The phenotypic trait is seen between dominant and recessive phenotypes in incomplete dominance. Likewise, in chromosomes, the phenotypes are illustrated by individual alleles in various parts of the body.

Another name of a heterozygous cell or organism is a heterozygote.

Related: 10 Differences Between Algae and Plants (With Table).

Some examples of heterozygous genotypes 

Sickle-cell anemia

Due to the trait of sickle-cell anemia, blood cells form in a wrong way. They turn into sickle shaped and comparatively tiny. It causes lack of oxygen.

Curly hair

We often notice so many people in our surroundings with curly hair. The reason behind this is the dominant trait and the individual having homozygous recessive alleles has straight hair.

The individual who has heterozygous genotype turns the hair wavier, which is between curly and straight. This is also called incomplete dominance, where the phenotype is expressed between the dominant and recessive ones.

Diseases from heterozygous genotypes

As homozygous genotypes, heterozygous genotypes are also related to genetic conditions.

If the mutated allele is recessive, then the disease will not appear, and the organism will act as a carrier.

Heterozygous genotypes are the reason of Huntington’s disease, Marfan’s syndrome, and familial hypercholesterolemia. These diseases are seen if the mutated allele i dominant. In case of recessive mutated allele, disease won’t appear.


In this article, we have tried to share all the differences between homozygous and heterozygous and also shared the diseases caused by these two. These two things are so significant in human’s life that none can ignore them. And we are sure, after reading this writeup, all the opaqueness related to homozygous and heterozygous have got vanished.

The FAQs about Homozygous vs Heterozygous

What is the difference between homogeneous and heterogeneous?

“Hetero” – indicates difference and ” Homo” – indicates similarity. A homogeneous mixture has the same uniform appearance and composition throughout. A heterogeneous mixture consists of visibly different substances or phases.

What is a homogeneous  and heterogeneous mixture and examples?

Homogeneous mixture is the uniform mixture of two or more things. On the other hand, heterogeneous mixture is the nonuniform mixture of two or more things.

Some examples of homogenous mixtures are air, saline solution, most alloys, and bitumen. And the examples of heterogeneous mixtures are sand, oil and water, and chicken noodle soup.

Is coffee homogeneous  or heterogeneous?

Yes, coffee is an example of homogeneous mixture.

Is Salt a homogeneous mixture?

Yes, salt is a homogeneous mixture.

What are the 5 examples of homogeneous mixture?

5 examples of homogeneous mixture are sea water, wine, vinegar, steel, brass.

Is Pizza homogeneous or heterogeneous?

Pizza is a heterogeneous mixture because its components are not uniform.

Minhajul Islam

Minhajul Islam is a passionate technology writer and the founder of DifferencePlanet. He is dedicated to exploring the latest advancements in the tech industry and sharing his insights with the world. With a background in computer science and a keen interest in smart homes, Minhajul has written numerous articles on a wide range of tech topics. He believes that technology has the power to transform the way we live, work, and interact with the world around us, and is always on the lookout for the next big thing.

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