Information encoding all the proteins of the body is recorded in cellular DNA. There are only 4 types of nucleic bases - and countless combinations of amino acids. Nature made sure that every failure was not critical and made the genetic code redundant. But sometimes the distortion still creeps in. It is called a mutation. This is a violation in the recording of DNA code.
Useful - rare
Most of these distortions (more than 99%) are negative for the body, which makes the theory of evolution untenable. The remaining one percent is not able to provide an advantage, since not every mutated organism produces offspring. Indeed, not everyone has the right to reproduce in nature. Mutation of cells more often occurs in males - and males, as you know, in nature die more often without producing offspring.
Guilty women
However, man is an exception. In our species, the mutation process is most often triggered by the irresponsible behavior of females. Smoking, alcohol, drugs, STDs - and a limited supply of eggs exposed to negative effects from early childhood. If for men a safe dose of alcohol exists, then for women even a small glass can provoke disturbances in the correct formation of eggs. While European women enjoy freedom, Arab women abstain - and give birth to healthy children.
Incorrectly recorded
Mutation is a constant change in DNA. It can affect a small area or an entire block in the chromosome. But even a minimal violation shifts the DNA code, forcing to synthesize completely different amino acids - therefore, the entire protein encoded by this site will be inoperative.
Three types
A mutation is a violation of one of the species - either an inherited one, or a de novo mutation, or a local mutation. In the first case, these are hereditary diseases. In the second - a violation at the level of the sperm or egg, as well as the consequence of exposure to hazardous factors after fertilization. Dangerous factors are not only bad habits, but also an unfavorable environmental situation (including radiation). A de novo mutation is a disorder in all cells of the body, as it arises from an abnormal source. In the third case, a local, or somatic, mutation does not occur in the early stages and does not affect all cells of the body, with a high degree of probability it is not transmitted to offspring, in contrast to the first and second types of disorders.
If problems arose in the early stages of pregnancy, then a mosaic disorder occurs. In this case, part of the cells is affected by the disease, part - not. In this form, it is highly likely that the child will be born alive. Most genetic abnormalities cannot be seen, because in this case miscarriages often occur. The mother often does not even notice pregnancy, it looks like a delayed period. If the mutation is harmless and occurs frequently, it is called polymorphism. This is how blood groups and iris colors came about. However, polymorphism can increase the likelihood of some diseases.