Genetic Variation

Genetic Variation Genetic Variation is defined as being the differences amongst individuals in the composition of their genes or other DNA sequences. This can variation can be a wide variety of things from fur color to number of seeds or even height.

Mutations Remember that a mutation is any change the DNA of an organism. You have regions in your DNA that code for information. The coding regions of your DNA are called exons. The noncoding regions of the DNA (regions that do not code for a protein) are called introns. Most mutations that occur in human DNA are found on introns, thus they almost never affect the protein coding exons of your DNA. About 98% of your DNA is made of introns. Although introns are called “junk” DNA, it is possible that this DNA could have other functions.

Sources of Genetic Variation Forming new alleles through a mutation is one way to cause a variation. Changing one base in the DNA is called a point mutation. Altering gene number and locations on a single chromosome can cause certain traits to magnify (if the gene is duplicated). Rapid reproduction in prokaryotes can lead to more variation. Even though they have fewer genes, they have way more offspring per unit of time, thus furthering the likelihood of mutation. Sexual reproduction can also cause a larger than average rate of variation, as the offspring are a recombination of the parental DNA. This variation is caused mainly by crossing over, assortment of chromosomes, and fertilization.