As in comics, where mutations give superheroes powers, mutations in nature can sometimes give organisms extraordinary powers of adaptation.
But what is a mutation? A mutation is an alteration or change in DNA. The DNA code has four letters or nucleotides, A, T, C and G. Just like in language, when we change a letter we can change the meaning of words (for example SIT and SAT), or suppress it (SWT, SCT, do not mean anything). In DNA, changes or mutations in a nucleotide can modify the information encoded or cancel it. For example, a change from C to T in a certain region of our DNA is the causal mutation that allows us to digest milk throughout life, and not just when we are young enough to nurse.
In addition to single-letter changes, other types of changes or mutations also occur in DNA, such as those caused by moving elements. Moving elements or jumping genes are pieces of DNA that have the ability to jump from one part of the genome to another, sometimes causing many changes.
Changes or mutations in DNA, such as changes from one nucleotide to another, or changes of DNA fragments from one place to another in the genome, are the origin of VARIABILITY.
Did you know that… unlike humans, most mammals cannot digest milk when they are adults?
Changing a C nucleotide to a T nucleotide in a region close to the lactase gene allows this gene to remain active throughout our lives. When the lactase gene is active we can digest the lactose present in milk and other dairy products, such as cottage cheese. Scientists believe that the first carriers of this change in DNA were able to survive better in colder climates, where very little could be grown in winter. These people,who carried the mutation, were able to have more children than those who did not, and this way, the mutation spread amongst the population throughout the generations. Scientists have identified up to four different changes in the DNA around the lactase gene that allow us to digest milk and its derivatives. Identifying these DNA changes has allowed us to design genetic tests that make it possible for us to diagnose whether or not a person has lactose intolerance quickly and non-invasively.
Did you know that… we can differentiate colors due to a mutation caused by a moving element?
Humans, along with some other primates, are the only mammals that have trichromatic vision (i.e. we can see three primary colors: red, green, and blue): we have three pigments called opsins that allow us to distinguish these colors. Scientists have discovered that the duplication of opsin genes is due to a mobile element.
