Genotypic Variation: Definition & Example

Genotypic Variation: Definition & Example
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  • 0:01 What Is Genetic Variation?
  • 1:11 How Does It Happen?
  • 3:17 Examples of Genotypic…
  • 4:06 Lesson Summary
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Lesson Transcript
Instructor: Kelly Robson

Kelly has taught High School Science and Applied Communications. She holds an Education Specialist Degree in Ed. Leadership.

Genotypic variation is what makes us all different and lead to many diverse species and individuals. This lesson takes you through what genotypic variation is, the causes, and some of the effects.

What is Genetic Variation?

A genotype is the genetic blueprint of an individual. It's the internal code that determines how everything is formed. The physical result of the genotype is the phenotype. For example, the genotype is the genetic code that tells the eyes to be blue. The phenotype is the resulting blue color of the eyes.

There are many ways to build a building. The same is true for ways to build a species or an individual of a species. For the sake of simplicity, let's just talk about genotypic variation in humans. It's easy to see that there are many different ways to build a human. What you are looking at is the phenotype of the person. Behind the physical appearance of each person is a more complicated code telling each individual how it needs to be structured. This behind-the-scenes factor is the genotype. There are many diverse codes out there, and this causes genotypic variation.

More specifically, genotypic variation is the variation in genotypes either between individuals of the same species or between different species as a result of genetic mutation, gene flow, or something that occurred during meiosis.

How Does it Happen?

If everybody's genes are inherited, passed down from parents, then how is there so much genetic diversity in a single species? There are different causes for these variations. Three ways the variations can occur genetically are with mutations, gene flow, and meiosis.

If the genotype is the blueprint and the phenotype is the structure, then the DNA is the architect that is the master of how the species is formed. A mutation is a change in DNA. The changes may be passed down to offspring for many generations. Over time, the mutations that are inherited cause changes in the way species are built. Mutations are the reason that evolution occurs. A mutation's effect could go unnoticed, but a single mutation can also cause a lot of damage to an individual.

Sickle cell anemia is an example of a genetic mutation. It's caused by a substitution in the beta-hemoglobin gene. This substitution alters only one amino acid in the protein. Basically just a little glitch in the genes causes a person's red blood cells to form incorrectly. Instead of their red blood cells being all squishy and disc-shaped, they become stiffer, sticky, and crescent shaped. Sickle cell anemia is a very painful disorder that is caused by a single mutation in a person's genetic makeup.

Another cause for genetic variation is gene flow. Gene flow occurs when individuals add their genetic make-up to other populations. This addition causes the affected population to expand their gene pools. Basically, the genes are flowing from one pool to another. This allows for mixing things up and expanding the different combinations of available genotypes.

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