What Is The Difference between Homozygous and Heterozygous?

What is the difference between homozygous and heterozygous? Homozygous refers to an individual having two identical alleles for a particular gene at the corresponding loci on homologous chromosomes while Heterozygous refers to an individual having two different alleles for a particular gene at the corresponding loci on homologous chromosomes.

The terms “homozygous” and “heterozygous” refer to the genetic makeup of an individual with respect to a particular gene or trait. The key distinction lies in the similarity or dissimilarity of the alleles at a specific gene locus. Take the time to read the entire post for better understanding.

Difference Between Homozygous and Heterozygous (With Table)

Basic Terms Homozygous Heterozygous
Meaning Occurs when the diploid organism carry identical alleles Occur when the diploid organism carry different alleles
Result Pure traits such as RR or rr Dissimilar traits such as Rr
Carries Identical alleles Different alleles
Type of alleles Either dominant or recessive One dominant and the other recessive
Gametes produced One type Two different types
Vigour Does not exhibit extra vigor Exhibit extra vigor such as hybrid vigor
Self-breeding Same trait over generations Combination of different traits
Examples Human blood type O Human blood type AB

What Is Homozygous?

“Homozygous” refers to a genetic condition where an individual has two identical alleles for a specific gene located at the same position (locus) on homologous chromosomes.

There are two types of homozygosity:

  1. Homozy

  2. gous Dominant (HH): In this case, both alleles are dominant. If a gene for a certain trait has a dominant allele represented by a capital letter (e.g., ‘H’ for brown eyes), a homozygous dominant individual would have two dominant alleles (HH) for that trait.

  3. Homozygous Recessive (hh): In this case, both alleles are recessive. If a gene for a certain trait has a recessive allele represented by a lowercase letter (e.g., ‘h’ for blue eyes), a homozygous recessive individual would have two recessive alleles (hh) for that trait.

What Is Heterozygous?

“Heterozygous” refers to a genetic condition where an individual has two different alleles for a specific gene located at the same position (locus) on homologous chromosomes.

The two types of alleles may be represented by different letters or symbols. The dominant allele is usually represented by a capital letter, while the recessive allele is represented by a lowercase letter.

For example, if a gene for eye color has a dominant allele for brown eyes (B) and a recessive allele for blue eyes (b), a heterozygous individual would have one dominant allele and one recessive allele (e.g., Bb).

This genetic diversity can lead to a range of phenotypic expressions, as the dominant allele often determines the observable trait while the recessive allele is masked in the presence of a dominant allele.

Main Difference between Homozygous and Heterozygous

  1. Homozygous results in similar individuals with pure traits while heterozygous results in dissimilar individuals with different traits.
  2. Homozygous have identical alleles while heterozygous have different alleles
  3. Homozygous is either dominant or recessive while heterozygous have one dominant and one recessive.
  4. Only one gamete is used in homozygous while heterozygous two types of gametes are used.
  5. Homozygous do not exhibit extra vigor while heterozygous exhibit hybrid vigor

Similarities between Homozygous and Heterozygous

  1. Both used in the description of genotype
  2. Both present on the same locus of homologous chromosomes.
  3. Both involve alleles, which are different forms of a gene.
  4. Both conditions involve alleles located on homologous chromosomes.
  5. Both represent the genetic information for a particular trait or gene
  6. Both conditions are applicable to diploid organisms with pairs of homologous chromosomes.

You May Also Like:

Subscribe To My Channel

Conclusion

The difference between homozygous and heterozygous lies in the genetic makeup at specific gene loci. Homozygous individuals possess two identical alleles—either both dominant or both recessive—resulting in a uniform expression of a particular trait.

On the other hand, heterozygous individuals harbor two different alleles, with one being dominant and the other recessive, contributing to genetic diversity and varied phenotypic expressions. This fundamental contrast in genetic composition underscores the intricate interplay of alleles in shaping the observable characteristics of organisms.

More Sources and References

Leave a Comment