Facts About Genotypes That Everyone Should Be Aware Of!

A genotype typically completes a heritable genetic makeup.

In genetics, the term 'genotype' refers to a particular gene or a set of genes to define the physical traits of an individual. For example, if a person carries a genetic mutation related to specific physical characteristics, it is directly linked to the genotype, without any consideration of all the other gene variants.

A genotype is a set of instructions that is responsible for almost everything about an organism, which in this case, includes unique genetic characteristics. That is why some peas have wrinkles and others are smooth.

In a human body, the genetic makeup is responsible for the person's physical traits and diseases. For example, if a person has hemophilia, it is believed the IX factor deficiency is definitely acquired from one of the parent genes.

A genotype can be determined by biological tests.

Historical Facts

The term 'genotype' was first coined by Wilhelm Johannsen. Given its integral association within the biology community, here are some historical facts about genotypes.

Johannsen introduced the concepts of genotypes and phenotypes in his textbook on hereditary research, titled 'Elemente der exakten Ereblichkeitslehre' ('The Elements of an Exact Theory of Heredity'), in 1909. He then developed the terms fully in a 1911 paper, 'The Genotype Conception of Heredity'.

Johannsen performed pure line breeding experiments on barley and common bean plants to derive the concepts. The whole experiment was a part of Johannsen's campaign against the 'Transmission Concept of Heredity', which means the physical characteristics of an individual are transmitted directly to their offspring. One of the notable examples of the 'Transmission Concepts' included Darwin's theory of 'Pangenesis'.

Examples of Genotypes

A gene is a section of DNA to encode a trait. The precise arrangement of nucleoids in a gene can be different in two copies of the same gene.

An organism's genotype can exist in different forms, known as alleles. A diploid organism can either inherit two copies of the same allele, or one copy of two different alleles, from their parent genes. Based on this, there are three types of genotype present.

Homozygous Dominant: If an individual inherits two identical alleles from their parents, that type is known as Homozygous Dominant Genotype. For example, eye color; brown eye color is often dominant over blue eye color.

If an individual has brown eyes, they might have either two alleles for brown eyes, or one for the brown allele and one for the blue allele.

Heterozygous: Heterozygous genetic makeup refers to having inherited different forms of a particular gene from each of the parent's genes. For example, freckles; tiny brown-black spots on the skin made up of melanin, are controlled by the MC1R gene. An individual having freckles has the heterozygous genotype for the recessive version, which causes them.

Homozygous Recessive: When an individual inherits one allele for a dominant trait and another allele for a recessive trait and has the recessive trait as dominant, they have Homozygous Recessive genetic information. For example, a person heterozygous for red hair, has one allele for a dominant trait such as brown hair and one allele for red hair.

Homozygous Recessive genetic makeup is a unique genotype. If the child inherits the same allele of red hair from one of the other parents, they will be homozygous and have red hair.

Apart from physical traits, genotypes are also responsible for some diseases caused by muted alleles in an organism. If an organism is homozygous for the recessive muted gene, they have a higher probability of acquiring the disease. Some examples of this include:

Cystic Fibrosis: A person with two inherited muted copies of the CFTR gene will have this disease. Every person with Cystic Fibrosis is homozygous for this mutation.

Sickle Cell Anemia: Caused by HBB (Hemoglobin subunit Beta) gene.

Phenylketonuria: Occurs when a person is homozygous for a phenylalanine hydroxylase (PAH) mutation.

Genotype vs Phenotype

The genotype is the chemical composition of its DNA, which paves the way to the phenotype, or the observable traits, in an organism. A genotype consists of all the nucleic acid in the genome that codes for a particular trait.

The phenotype is the outward appearance, the result of the interactions of all the protein cells created. The sum of all the observable characteristics in a genome is the phenotype.

Though a phenotype is highly influenced by genotype, a genotype does not equal a phenotype. The phenotype depends on many external factors:

Environmental factors: The environment plays a major role in the phenotype of genes. Factors such as diet, temperature, oxygen levels, humidity, light cycles, and stress have an impact on the gene cells of an organism.

For example, with the PTC tasting experiment, scientists have estimated that genetics controls about 85% of the ability to taste. Environmental factors play a role in controlling the dryness of the mouth or how recently the person has eaten.

Epigenetic Modifications: Epigenetic modifications are highly dominant due to factors like genetic change, DNA methylations, histone modifications, and m1RNA changes. For example, smoking can change a person's genetics. Smokers tend to have less DNA methylation at certain parts of the AHRR gene than non-smokers.

Observing the phenotype is simple as it is the outward appearance. However, observing the genotype is a little more difficult. It is analyzed using biological assays and whole-genome sequencing.

Understanding the difference between a genotype and phenotype is extremely useful in a variety of research areas. Using animal models, such as using a mouse's influence, and modifying an organism to express specific genes are ways of studying phenotypes.

Other Miscellaneous Facts

Genotypes are represented with alphabetical letters, such as Bb, where B stands for dominant allele and b stands for the recessive allele. A phenotype is the result of the expression of these genes.

As the phenotype is influenced by various outside factors, no two individuals with an identical genotype look the same, nor do all the monozygotic twins have the same genotype.

Genotypes, like phenotypes, are not observable from the outside. Rather, tests such as genotyping have to be performed.

The term 'pheno' in 'phenotype' means 'observe' and indicates the observable traits in an organism, such as height and color.

The morphology, physical form, structure, development, behavior, and biological and physiological properties of an organism are covered by its phenotype.

The phenotype depends on two factors; the expression of the gene and its interaction with the environment.

The environmental, physiological, and morphological changes associated with age also contribute to a variation in phenotype.

Phenotype variations form the basis of natural selection. The environment favors the survival of the fittest. This phenomenon is clearly observed in the case of twins, where individuals possessing identical genotypes express different phenotypes, if they encounter a different environment.

This environmental change affects the G-C content of the genome, which causes an increase in thermal stability, which in turn allows the body to survive in high-temperature environments.

The process of determining the genotype of an individual is termed genotyping, which can be used for various purposes like PCR, DNA sequencing, and Restriction Fragment Length Polymorphism (RFLP).

Various examples of a phenotype are seen in a number of organisms, such as eye color, blood group, hair texture, genetic diseases in humans, pea pod size, the beak of birds, and the color of leaves.

Examples of genotype are seen in different animals, which include Tt for the heterozygous allele in case of height, TT as the homozygous allele for also determining height, and BB for the homozygous allele for eye color.

FAQs

What is an example of a genotype?

An example of a genotype is the presence of blue eyes in an individual. The blue allele is a homozygous recessive gene, but the genetic dominance results in blue eyes.

What makes up a genotype?

Two alleles inherited in a single gene make up a genotype.

What does a genotype do?

Genotypes typically pass on the unique genetic composition of an individual consisting of heritable genes.

What are the characteristics of genotypes?

The basic characteristics of genotypes are:

A genotype is the chemical composition of the gene of an organism, consisting of all the nucleic acids present in a DNA molecule that code for a particular trait.

There are three types of genotypes; homozygous recessive, heterozygous, and homozygous dominant.

A genotype makes the way for the phenotype, which are the observable traits of an organism.

What is a medical issue related to genotypes?

Some of the medical issues associated with genotype mutations include Sickle Cell Anemia, Cystic Fibrosis, and Phenylketonuria.

How do I know my genotype?

A genetic test will help you learn your genotype.

Which genotype has the strongest immunity?

In the human body, the AA genotype has the best immunity. People with the AA genotype have the least chance of inheriting Sickle Cell Anemia.

How many genotypes do we have?

A description of the pair of alleles in our gene is called the genotype. Since there are three different alleles, there are a total of six different genotypes at the human ABO genetic locus. The different possible genotypes are AA, AO, BB, BO, AB, and OO.

What genotype causes Sickle Cell Anemia?

Sickle Cell disease is caused by inheriting two copies (one from each parent) of an altered HBB gene, which causes the production of an abnormal form of beta (β)-globin, such as hemoglobin S (HbS).

Who discovered the genotype?

The term 'genotype' was coined by the Danish botanist, Wilhelm Johannsen, in 1903.