Genotype and Phenotype Difference


Genotype Definition

Genotype accounts for the genetic constitution of an individual, that is it refers to the actual set of genes present in the organism. For sexually reproducing organisms, the genetic material comprises DNA, which are contributed to it from the egg and sperm of the respective parents. Precise molecular mechanisms control the transfer of genes from parents to the offspring. Organisms possessing genes that differ in even one locus are known to have different genotypes. In asexually reproducing organisms, the genetic material is an exact copy of the DNA of its parent, because there is no fusion of egg and sperm. One genotype example would be Tt, which are the alleles for tallness. Capital T and small t stand for the dominant and recessive genes respectively, which form the genetic makeup. Read more on dominant and recessive traits in humans.

Phenotype Definition

Phenotype refers to the observed traits or anatomical features of an individual, such as structure, physiology and behavior. Physical and behavioral characteristics such as size, shape, color, metabolic activities, etc. all come under phenotype of an organism. These physical attributes and behavioral characteristics determine the organism’s ability to survive and reproduce in the environment. The genotype of an organism determines the phenotype of an organism to a large extent. A phenotype example would be Tt, which will appear as a tall person. The dominant capital T, will result in the physical characteristic of tallness, in the person, which is visibly seen.

Genotype and Phenotype Difference

The genotype of an organism determines majority of its phenotype. Thus, phenotypes depend on the genes they inherit. However, genes are not the only factor. The phenotype of an organism is determined by three factors: the genetic make up, received from parents; the environment and development noise. Let’s take the example of hair. Presence of hair on the head is determined by the genes of an individual, however, the time period for which the hair will remain on the head will depend on environmental factors like chemicals used on the head, excess sunlight, stress, poor diet, etc. This itself shows that the environment influence plays a role in the phenotype.

There are several organisms which have similar genetic makeup, that may differ in their phenotypes. The best example to explain this point is by considering the case of identical twins. Identical twins look alike and have the same genetic make up. (Fertilized egg splits into two, to form identical twin zygotes that grow to form two identical babies). However, they have different phenotypes. How? Well, they do have some differences, although they seem identical. Their parents and close ones can always tell one twin from another. Then again, their fingerprints also differ. Thus, organisms or individuals can have same genotype, but have different phenotypes.

“In simple sense, the genotype defines the phenotype, although not completely.”