Why aging occurs and what reasons of irreversible age-related violations? On the one hand, the answer lies on the surface. Many scientists have a the

Theories of aging

Why aging occurs and what reasons of irreversible age-related violations? On the one hand, the answer lies on the surface. Many scientists have a theory of aging assuming that the aging of the human body is like a machinery wear. However, on the other hand, the body, in contrast to, for example, the vehicle, is a self-regulating and self-healing system; therefore it is wrong to equal the aging process just to irreversible deterioration of certain organs — the body parts.

Scientists often explain aging by processes occurring at the molecular level of the organization. This is, particularly, accumulation of unwanted active substances — chemical radicals. They interact with proteins and nucleic acids, causing damages that impair their function. So radicals interact with DNA leads to point mutations, which are the result of violations of the protein structure. It is necessary to add that mutations in the cells can be caused by other factors. Mutations tend to accumulate over a lifetime, and that’s why in the old cells a lot of “wrong” protein is being synthesized.

There are other theories of aging. It was found that human cells can divide at most 50 times, after which the die. It turned out that the cause of their programmed death is that after each cell division special enzymes kind of “bite off” small pieces from the end, a specially structured chromosome region, called a telomere (from Greek “telos” — “end” and “meros” — “part”) (diagram 94). After 50 divisions, all the telomere becomes “eaten”, and the cell dies. Researches have shown that organisms whose cells are capable of an infinite number of divisions (unicellular organisms, multicellular plants and animals that can reproduce vegetatively), there is a special enzyme telomerase, which regenerates the lost areas. Taken from http://worldofschool.org

Diagram 94. Telomeric regions of chromosomes, the presence of which allows human cells share no more than 50 times

That is why many scientists believe that the maximum human life span can be extended only by means of genetic engineering. Integrating into human cells a gene, encoding telomerase, you can provide them with an infinite number of divisions, opening the way to immortality.

Questions:
  • Why does aging occur?

  • What are the theories of aging?