Genotype and phenotype are two terms used when explaining and differentiating the genetic makeup of an individual as well as the expression of traits. The genes and other factors (epigenetic and environmental factors) determine the expression of traits.
Genotype is our genetic makeup, while phenotype are the observable characteristics. The main difference between genotype and phenotype is that while genotype is the complete genetic makeup of an individual, phenotype are the observable characteristics of the expressed gene due to environmental conditions.
What is a Genotype?
Genotype is the complete set of genes in an organism. Genotype is called the “blueprint” of the cell, and carry the instruction for the genetic makeup or sequence of genome of the individual. The instructions are written with genetic code.
Genotype is inherited through progeny via reproduction, and determines our characteristics, appearance and behavior. Two individuals with the same genotype can have different observable characteristics, such as appearance and behavior. Observable characteristics can be modified by epigenetic factor and environmental factors.
The environmental factors include exposure to pollutant, diet, while epigenetic changes include DNA methylation, histone modification, and Non-coding RNA.
In a polyploid organism, like the human being, a combination of alleles determine the genotype. Alleles can be homozygous or heterozygous or the locus. They can also be dominant or recessive, depending on the phenotype. Alleles occurs in pairs.
When an individual inherits two identical alleles, it is termed homozygous at that locus. But if the inherited alleles are different, it is said to be heterozygous for that locus.
A dominant allele exhibits their effect even if there is only one copy of the allele (heterozygous). For example, the allele for brown eyes are dominant. Even though two copies of the allele can give brown eyes, one copy can also give brown eyes.
Another term is codominance, when two dominant alleles are expressed equally, for e.g., AB blood group, with two dominant A and B alleles.
Most genotypes follow the Mendelian inheritance, after his studies on peas (Pisum sativum). In the Mendel’s flower, three genotypes, BB, Bb and bb, determine the color of the flower in pea plants. The dominant phenotype is purple, and white is the recessive phenotype. B is the dominant allele, while b is the recessive allele.
We can determine a genotype through a process called genotyping. The assay include PCR, RFLP, nucleic acid hybridization, DNA sequencing or DNA microarray techniques.
Different types of genotypes are homozygous dominant (PP), homozygous recessive (pp), and heterozygous (Pp). The homozygous dominant and the heterozygous genotypes show in the same phenotypes.
What is a Phenotype?
They are the physical manifestation like observable structures, functions, and behaviors. Genotype together with epigenetic and environmental factors determine the phenotype. Phenotypic polymorphism is the incidence of more than a single phenotype for a morphological trait.
The genetic makeup of an individual can be altered by a process called natural selection.
Also, some phenotypes are not visible, but can be determined using molecular biological or biochemical techniques like Western blotting, enzymatic assays, and SDS-PAGE.
The study of phenomes (collection of traits) is called phenomics.
Differences Between Genotype and Phenotype
The main differences between genotype and phenotype are:
| Genotype | Phenotype |
| Genetic makeup of an individual, in the form of genes in the DNA | It is the observable morphology, function, and behavior of an individual. |
| It is determined by gene sequence | Determined by genes and environmental factors. |
| The same genotype produces the same phenotype | Phenotype may be related to the same genotype, or not in some cases. |
| Genotype is hereditary, i.e., from parents to the offsprings | They are not inherited |
| Genotype is determined by genotyping method such as polymerase chain reaction | By observing outward characters, we can determine the phenotype. |
| Consists of all hereditary materials, both expressed and suppressed. | Only the expressed genes |
| Examples of genotype are hair color, eye color, height | Example includes brown, blue eye colors, black, or brown or blonde hair color. |
References:
- https://www.researchgate.net/publication/313997817_Difference_Between_Genotype_and_Phenotype
- https://www.sciencelearn.org.nz/resources/1999-mendel-s-experiments
- https://www.yourgenome.org/facts/what-are-dominant-and-recessive-alleles/
