WHAT ARE GENOTYPIC VARIATIONS? TYPES AND EXAMPLES - BIOLOGY - 2024

The genotypic variations are variations in genotypes among individuals of the same species or between different species as a result of genetic mutation, gene flow or something that happened during meiosis.

Genotypic variations between individuals of the same or different species are the result of genetic mutation, gene flow, or some event that occurred during meiosis.

The genotype is the genetic blueprint of an individual. It is the code that determines how everything will be formed. On the other hand, the phenotype is the physical result of the genotype or the physical expression of the genes.

For example, the genotype is the genetic code that determines that the eyes are blue and the phenotype is the blue color of the eyes resulting from this event.

What is seen with the naked eye is the phenotype, however behind the phenotype there is a complex process of gene codes or genotypes that determine how something will be.

Types of genotypic variations and examples

- Continuous variations

Continuous variations are those that are determined by the environment and by genes. These variations can be seen between several individuals of the same species.

Continuous variations tend to be gradual and small. Examples of these types of variations include body weight, height, hair color, and skin.

Skin color

The color of human skin ranges from the darkest brown to the lightest shades. The pigmentation of the skin of each individual varies according to their genetics, being the product of the genetic makeup of their parents.

In evolution, human skin pigmentation evolved through a process of natural selection, primarily to regulate the amount of ultraviolet radiation that penetrated the skin, controlling biochemical effects.

The substance that determines the color of the skin is called melanin. Individuals who are located in populations near the equator or who receive high amounts of UVR tend to have darker skin colors.

Skin color can also vary based on sun exposure, resulting in tanned or darker skin.

The genetic mechanism behind skin color is largely regulated by the enzyme tyrosine, which creates the color of skin, eyes, and hair.

Differences in skin color can also be attributed to differences in the size and distribution of melanomas on the skin.

There are several genes that can determine an individual's skin color. The MC1R gene determines what melanin the body makes; the KITLG and ASIP genes also have mutations associated with lighter skin color.

Just like these, there are many other gene combinations that play a role in melanin production and skin color.

Hair color

Hair color is the pigmentation of the hair follicles thanks to two types of melanin: eumelanin and pheomelanin.

Generally, if there is more eumelanin present, the hair color will be darker; if there is less eumelanin present, the hair will be lighter.

Melanin levels in hair can vary over time, causing hair color to change. A person can also have different colors of follicles on their body.

The darker a person's hair, the more individual hair follicles they will have on their scalp.

The scale that differentiates hair tones is called the Fischer-Saller scale and uses these designations: A (very light), B to E (light blonde), F to L (blonde), M to O (dark blonde), P a T (light brown to brown), U to Y (dark brown to black); Roman numerals I to IV determine red and V to VI the reddish blond.

It is not yet clear all the elements that determine hair color. At least two different pairs of genes are believed to determine hair color.

However, this model does not take into account the different shades between colors or explain why hair sometimes darkens as a person ages.

Height

Height is the distance from the feet to the head of the human body. When populations share the same genetic base and environmental factors, average height is a frequent characteristic of the group. Genetics are a big factor in determining the height of individuals.

Exceptional variation, such as more than 20% within a population, can sometimes be caused by factors such as dwarfism or gigantism. These medical conditions are caused by specific genes or abnormalities in the endocrine system.

The genetic potential and a number of hormones, discounting any disease, are basic determinants to determine the height of a person. Other factors include the genetic response to external factors such as diet, exercise, environment, and life circumstances.

One particular male genetic profile called Y-haplotype I-M170 is related to height. Ecological information shows that the more the frequency of this genetic profile increases in the population, the more the average male height increases in that place.

- Discontinuous variations

Discontinuous variations influence genes specifically and only. It can be said that a variation is discontinuous when the element is clearly expressed as different and is only genetically determined.

Additionally, they cannot be altered throughout an individual's life. Many inherited diseases such as albinism or dwarfism, in addition to blood type, fall into this category.

Blood type

Blood type is a classification of blood based on the presence or absence of antibodies and antigenic substances. The blood type is inherited from the parents.

If a pregnant woman carries a baby with an antibody opposite to hers, for example that she is factor + and the baby is -, she will need to undergo special treatment to carry the pregnancy to term.

Dwarfism

This disease occurs when an individual is unusually small in stature. The most common cause is achondroplasty, a disorder that is caused by the presence of a failed allele in the genome.

This condition is a mutation in the growth receptor; causes the FGFR3 gene to inhibit bone growth.

Recent studies suggest that this defect is inherited specifically from the father and becomes more common if the father reproduces after the age of 35.

References

1. Human height. Recovered from wikipedia.org.
2. Genotypic variation: definition and example. Recovered from study.com.
3. Blood type. Recovered from wikipedia.org.
4. Recovered from wikipedia.org.
5. Continuous and discontinuous variations. (2015) Recovered from slideshare.com.
6. Human skin color. Recovered from wikipedia.org.
7. Genetic and phenotypic variation. Recovered from studentreader.com.
8. Human hair color. Recovered from wikipedia.org.