An organism is a result of its genetic makeup and environmental factors. We all know that genes are the basic unit or structure of life. The study of genes is genetics.
If you look at genetics in the simplest form, it is all about the genotype or the genes inside the body and the phenotype of the traits or characters the genes gave you.
Read through this article to understand better the differences between genotype and phenotype.
What is a Genotype
In biology class, you learned that the person’s trait is encoded in the gene, which is a part of the DNA. The gene can exist in various forms (alleles).
A locus is the exact position of the gene on the chromosome. A genotype is homozygous at the locus if an individual inherits two identical alleles.
On the other hand, if the individual inherits two different alleles, then the classification is heterozygous for that locus.
To make it simple, the genotype is the subsequent combination of alleles that an organism possesses a particular gene. It was Wilhelm Johannsen, a Danish botanist, and geneticist who coined the term genotype. (1, 2, 3, and 4)
Examples of Genotype
It involves all genetic traits that can or cannot be passed onto the next generation such as:
- TT – height’s homozygous allele
- TT – height’s heterozygous allele
- BB for a homozygous allele for the color of the eyes.
What is a Phenotype?
It pertains to the organism’s observable traits and characteristics as a consequence of the genetic material and environmental factors.
It is different from that of genotype because the phenotype is not always inherited from the parents. Phenotype is influenced by genotype and other factors such as the lifestyle, environment, and epigenetic modifications.
Unlike the genotype, the phenotype can change throughout the lifetime. (3, 4)
Examples of phenotype
- The color of the eyes
- Texture of the hair
- Blood group
- Beak of the bird
- The size of the shoe
- Sound or pitch of voice
- Color of the leaves
Refer to the table below for a detailed comparison between genotype and phenotype.
|Basis for comparison||Genotype||Phenotype|
|Meaning/definition||It pertains to the genes in the DNA responsible for a specific trait.||It pertains to the organism’s traits and characteristics that can be observed.|
|Process of determining||Genotyping methods like WGS, PCR, DNA sequence||Can be characterized by simply looking at the organism’s outward features.|
|Inherited||Genotypes are inherited traits. (4)||Phenotypes aren’t inherited. However, can be partly inherited from one of the two alleles during sexual reproduction. (4)|
|Depends on||The organism’s gene sequence.||It depends on the genotype and other factors like environment and epigenetics.|
|Information it carries||Full hereditary information is determined by the genes passed on by the parents during conception. (5)||It carries expressed genes, which can change according to which genes are expressed and the effects of the environment on them. (5, 6)|
|Etymology||It comes from the German word genotypus meaning offspring.||It is derived from the German word phaenotypus which means the sum total of the observable traits.|
|Visibility||Cannot be visualized using the naked eyes.||Can be visualized using the naked eyes.|
|Scope||It encompasses all genetic traits that can be passed on by parents to offspring. (6, 7)||It encompasses all observable traits such as height, color, physical form, structure, morphology, development, and behavior. (7)|
|Variation||It is affected by several factors such as gene mutation and the DNA sequence structure.||It is observed within an individual due to factors like physiological, morphological, and environmental changes relevant to age. It forms the basis of natural selection. (7, 8)|
|Susceptibility to change||It remains the same throughout the life of the organism provided it is affected by mutations of genes. (6, 7)||It can change throughout life such as the color of the hair and skin.|
|Ease of identification||No. Genetic testing has to be done.||Yes. All the traits are observable.|
|Affected by||It is affected by the genetic composition of an organism which is affected by sexual reproduction. (8, 9)||It is affected by environmental factors.|
|Relation||The exact genotype always leads to the same phenotype unless there is a genetic mutation. (3, 6)||The exact phenotype can or cannot be expressed from the same genotype.|
|Examples||Hereditary characteristics that can or cannot be expressed in the next generation. –
TT – height’s homozygous allele – TT – height’s heterozygous allele -BB for a homozygous allele for the color of the eyes. (3, 6)
Summary of key differences
- Genotype is all about the hereditary or genetic composition of an organism while phenotype pertains to the observable and visible traits and characteristics in relation to the expression of genes.
- Genotype remains the same throughout life while phenotype may change as an organism grows old.
- The genetic traits of the organism in genotype may or may not be passed on in the next generation. In phenotypes, the traits or characters are not inherited. Hence, the same phenotype can or cannot belong to the same genotype.
- Genotypes are the genetic composition and found at the cellular level. There are instances when a different genotype produces the same phenotype. In phenotype, a minute difference will have a different genotype and can be easily identified as they are observable physical traits. (4, 6, and 10)
- When it comes to the ability to inherit the traits, genotypes are partly inherited from the organism to the offspring as of the two alleles during the reproduction stage. Phenotypes, on the other hand, are not inherited. They are purely the expression of the parent’s genetic characteristics.
- In a particular time and environment, an organism with the same genotype will produce the same phenotype. However, an organism with the same phenotype might not belong to the same genotype.
- In phenotype, you can easily notice the physical traits by means of observation, specifically the color of the hair, the shape of the body, the color of the eyes, as well as the color of the skin. In genotype, you need to use a special tool such as the Polymerase Chain Reaction. (3, 5, 8, and 10)
Genotype and phenotype explained in a nutshell
Genotypes and phenotypes are used interchangeably but there are distinctions between the two. Phenotype is all about the organism’s physical appearance while the genotype refers to the organism’s genetic composition.
Genes are minute structures, which simply means that it is hard to distinguish genotype using only the naked eyes. Phenotypes are observable traits and are a result of the expression of the genes of an organism. (1, 5, and 8)
What does it mean? It simply denotes that with just a little difference in the organism’s genotype, there is a huge difference in the phenotype or observable traits. The phenotype traits are easier to detect than the genotypes.
You can easily check for the color of the eyes, hair, and skin, but will have a hard time looking at the genes responsible for such observable traits. You need to keep in mind that not all phenotypes are a result of the genotype.
The truth is most of the phenotypes are affected by the genotype as well as the exposure to various environmental and life elements. Your unique circumstances in life including the distinct things that happened to you can greatly affect your phenotype.
In genetics, it is referred to as nature (distinct genome you have) and nurture (environment in which you have lived your life).