Biology Science

Difference between Homozygous and Heterozygous

Main Difference

The internal structure of humans may well be the most complex chain that we know but some structures within them show even more sophisticated ratings and therefore knowing about them becomes essential. The two terms getting discussed in this article are the ones as follows. Homozygous gets defined as the particular gene inside the human cell that has alleles matching each other in an identical manner on the homologous chromosome. On the other hand, heterozygous gets defined as the particular gene inside the human cell that has alleles present with each other in a unique manner on the homologous chromosome.

Comparison Chart

Basis of DistinctionHomozygousHeterozygous
DefinitionThe particular gene inside the human cell that has alleles matching each other in an identical manner on the homologous chromosome.The particular gene inside the human cell that has alleles present with each other in a unique manner on the homologous chromosome.
ExpressionWe use the capital letters and write XX.We use the capital letters and write XY.
AlleleA person may only have either the dominant or the recessive alleles.A person may keep both the dominant and the recessive alleles.
ReproductionEnds up reproducing the same types of offspring.Gives rise to either same or different family.
GametesAlways one.Always more than two.

Homozygous

Homozygous gets defined as the particular gene inside the human cell that has alleles matching each other in an identical manner on the homologous chromosome. The way of expressing is different from others when we talk about the dominant trait within the structures we use the capital letters and write XX. But when we speak of the less dominant character we use, the smaller letters and write xx. It gets known that a diploid organism has two sets of alleles and humans fall in the same category. A complete human being structure includes 23 sets of chromosomes expressed as X and Y whereas 22 others. All of them have identical copies, and therefore it becomes possible that any of them may have similar or different actions. When a person has various forms of the same genes, then it gets known as alleles, and when the same type of alleles exists within the cell, then we call it the homozygous structure. These can either become dominant or recessive; then the dominant one takes the precedence over the less dominant. Let us say that a human eye has the dominant trait of brown color and the recessive trait of black color, then the eye will always show as brown but with few variations of black since the brown color gets known as dominant and the black color or any other color becomes recessive in nature.

Heterozygous

Heterozygous gets defined as the particular gene inside the human cell that has alleles present with each other in a unique manner on the homologous chromosome. However, when we discuss the less supreme quality, we utilize, the littler letters and compose xx. It gets realized that a diploid creature has two arrangements of alleles. The way of expressing is different from others when we talk about the dominant trait within the structures we use the capital letters and write XY. But when we speak of the less dominant character we use, the smaller letters and write xy. The example of such a structure become similar to the one given for the homozygous. Let us take a human eye, if it has an allele that shows the brown color and another allele that shows black color and neither of them is dominant or recessive but just different from each other, then, anyone of them takes precedence. Since a human has two copies of the DNA within them, one from their dad and one from their mother. Either one of them exists at the same time, in that case, we say that a person is heterozygous. If brown color takes over the black color, then eventually the first one becomes dominant, and the latter one becomes recessive. Some traits within this category fall into other patterns that get known as codominant, that means if a heterozygous has a phenotype that is different from a homozygous then we neither call it dominant nor recessive.

Key Differences

  • Homozygous gets defined as the particular gene inside the human cell that has alleles matching each other in an identical manner on the homologous chromosome. Whereas, heterozygous gets defined as the particular gene inside the human cell that has alleles present with each other in a unique way on the homologous chromosome.
  • The blood type of a person having homozygous allele may become AA, BB or OO depending on the arrangement whereas the blood type of a person having heterozygous may have AO, BO or AB genotype.
  • When we talk about the dominant trait in homozygous within the structures, we use the capital letters and write XX. But when we speak of the prevailing feature within the structures of heterozygous we use the capital letters and write XY.
  • A person having homozygous traits may only have either the dominant or the recessive alleles, on the other hand, a person having heterozygous trait may keep both the dominant and the recessive alleles.
  • A homozygous individual ends up reproducing the same types of offspring whereas a person with heterozygous traits gives rise to either same or different family.
  • The number of gametes produced by a homozygous always stays at one, whereas the number of gametes produced by a heterozygous always stays at two.

Video Explanation

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