science
Telomeres and telomerase.
The secret of prolonging life?
In recent years, telomeres and telomerase have been the main
candidates influencing the aging process to create an elixir of
rejuvenation and prolongation of life.
Telomeres (from other Greek telos - the end
and meros -part) - the end sections of the DNA
chromosomes. Telomere contains special DNA
sequences that ensure accurate replication of
chromosomes.
The telomeric regions of chromosomes are characterized
by a lack of ability to connect to other chromosomes or their
fragments and perform a protective function.
The term telomer was introduced in 1930 by the American
geneticist Hermann Joseph Müller (1890-1967), a Nobel Prize
winner in physiology (1946).
Even then, scientists suggested that the telomeres protect the
chromosomes from degradation.
Later, scientists calculated that in the human body there are 23
pairs of nuclear chromosomes, that is, only 46 pieces. Thus, a
human body has 92 telomeres.
The Russian biologist-theoretician and leading researcher of
the Institute of Biochemical Physics of the Russian Academy
of Sciences Alexei Olovnikov (born in 1936), in 1971, advanced
the hypothesis that telomeres, with each division of the cell, are
shortened, which limits the proliferative potential of cells.
Based on the data of researchers of geneticists-
practitioners on the principles of DNA synthesis
in cells, Alexei Olovnikov proposed the hypothesis
of marginalotomy (cell counting and aging),
which explains the mechanism of operation of
such a counter.
In the matrix synthesis of polynucleotides, DNA polymerase
(the current name for telemeraise) is not able to completely
reproduce the linear matrix, the replica is always shorter in its
initial part.
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Therefore, after a certain number of divisions, the cell can no
longer be divided. This phenomenon was called the "terminal
under replication of DNA."
This hypothesis implies an
important conclusion - the
age of a person is related to
the length of telomeres. The
older the person, the smaller
the average length of his
telomeres.
The length of the telomeres and the rate of their shortening
depend on age. In humans, the length of telomeres varies from
15 thousand nucleotide pairs (so-called) at birth to 5 tons, etc.
for chronic diseases.
The size, amount and nucleotide composition of telomeres of
chromosomes depend on a certain enzyme, called telomerase.
The main function of telomerase in the cell is to
compensate for the shortening of telomeres that
occurs with each cell division.
Telomerase synthesizes telomeres due to the reverse
transcription of its RNA subunit. According to the calculations of
scientists, for one cell division of telomerase should synthesize
30-100 nucleotides, this is how telomeric DNA is shortened.
In 1985, American scientists
Carol Grader and Elizabeth
Blackburn discovered
telomerase in cells.
And 13 years later, in 1998,
they managed to "rejuvenate"
the cell culture with
telomerase.