We always evolve together with everything around us even if sometimes we do not realize it because the changes are internal and not visible to our eyes or because they are slow, so slow that they are noticeable only if analyzed by looking at the succession of dozens and dozens of generations of individuals. In the evolution, the genetic mutations that remain something mysterious to most and are not just what one imagines, or the change of genetic characteristics over time. Let's find out better then what phenomenon is hidden behind this term, also making some examples to give a shape to this concept.
What are genetic mutations
When it comes to genetic mutations we mean a large class of phenomena that also take very different forms but which have in common the presence of a stable and heritable modification within a nucleotide sequence of a genome or more generally of unbound genetic material (both DNA and RNA) to one genetic recombination but attributable to external agents or totally random.
When you have these changes, surely the genotype of an individual is modified, the phenotype instead it could also remain unchanged, it depends a lot on its characteristics and on how it is interacting with the environment in which it lives.
Because we decided to explain what the genetic mutations going to immerse ourselves in not always trivial concepts to illustrate? Because these changes are the little big steps that allow us to evolve. Thanks to the fact that every now and then by chance or due to external causes, our genetic material changes, so that a situation of genetic variability is created. This means that differences appear between organisms for one or more characters and when genetic recombination occurs, thanks to natural selection one has the survival of favorable mutations at the expense of unfavorable or even lethal ones.
Genetic mutation experts, the so-called geneticists, divide them into different categories taking as a reference the specific scale of action of each because the single alteration may concern a single gene, portions of the genome or the entire chromosomal set. When mutations involve a somatic cell they are transmitted to all cells derived from it by mitosis and can sometimes transform the former into malignant cells. This is how cancer or congenital malformations can arise. When mutations occur in the germline cells o in gametes are inherited and may eventually cause hereditary genetic diseases.
Before going to discover some examples of genetic mutations, a curiosity. Organisms faced with unfavorable mutations, try somehow to repair the DNA from damage by putting in place internal defense mechanisms to minimize the mutation rate.
Positive examples of genetic mutations
The concept of genetic mutations it is neither positive nor negative in itself, it is something that happens and that each time can have different and unpredictable consequences.
Let's start with some examples of positive mutations that often help us to live better without our knowledge. The one that allows us to digest milk and food derived from it it is a favorable genetic mutation, it is lactose tolerance. It dates back to about 8-10 thousand years ago, it would have occurred in the Caucasus area, spreading all over the world and making a large part of the human population able to take this category of foods without having particular problems. An intolerant part of the population remained but it is a minority and is concentrated in peoples who live in areas far from the origin of the mutation, such as Asians and Africans.
Another important example of favorable mutation concerns AIDS: technically we are talking about the deletion of 32 base pairs in the human CCR5 gene but in fact the consequence is human resistance to AIDS. It is more common in those born in Europe and appears to correlate with forms of resistance to the bubonic plague. Much more local but interesting to mention the mutation that is observed in the inhabitants of Limone sul Garda, relating to their resistance to the harmful effects of “bad cholesterol. This is why they are longer-lived.
Negative examples of genetic mutations
A genetic mutation can also cause serious diseases such as phenylketonuria, disease caused by a gene mutation that slows down or blocks the ability to transform the amino acid phenylalanine into tyrosine, causing neurological damage.
Less serious but always negative examples are color blindness and albinism, and then there is another problematic disease such as sickle cell anemia which involves altering the structure and function of red blood cells.
Genetic mutations for commercial purposes
It is not always the case that causes genetic mutations and not always external factors that we cannot control. Sometimes it is precisely by the hand of the human being that they occur and with a specific commercial purpose. In short, to earn more! The processes for the selection of organisms with advantageous characteristics are planned with the geneticists. This happens in both animals and plants. Just think about when they sell us some larger fruit or comfortably seedless.