Genetic aspects of aging and death

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The aging process is studied by the field of gerontology. Knowledge of the changes that accompany aging is important for adequate medical and preventive care for seniors. The aging process is individual.

Causes of aging[edit | edit source]

biological studies of aging are focused on phenotypic manifestations of aging cells:
- free radical theory – these reactive metabolites react with macromolecules of membranes, cell structures and nucleic acids; they gradually negatively affect their function;
genetic causes of aging - sought in the accumulation of somatic mutations:
- the functional consequences of gene and chromosomal mutations depend on their localization, frequency and type of cell damage; even non-lethal mutations disrupt the synthesis of proteins important for cell metabolism and renewal;
- mutations can reduce the adaptive capabilities of the cell and eventually cause its death.

Telomeres[edit | edit source]

For more information see Telomeres.

Molecular genetic findings demonstrate that age is programmed by the length of telomeres. Telomeres of chromosomes are made up of a large number of short repeats that are species-specific. In humans, the repetitive telomere sequence is TTAGGG with telomere lengths of 5-15 kb. The telomere is terminated by a single-stranded region; the telomere bases are methylated, allowing the formation of a specific hairpin in with methylated guanosines pair.

Telomer

The structure of the telomere prevents DNA cleavage by deoxyribonucleases, fusion of DNA molecules in the genome and allows replication of DNA without loss of terminal sequences. Telomere elongation is possible only by the complex enzyme telomerase (RNA dependent DNA polymerase). It is active only:

in germline cells,
bone marrow stem cells,
stimulated T and B lymphocytes
and in tumor-transformed cells.

In differentiated somatic cells, telomerase is not expressed and the lengths of the telomere shortens by about 100 bases with each cell division. Telomere shortening below 2,5 kb is critical for the cell, it stops dividing and apoptosis can be induced in it. Cells with longer telomeres are capable of diving more than cells with shorter telomeres.

Signs of aging[edit | edit source]

Aging is manifested by a decline in the function of individual organ systems. Basal metabolism, pulmonary ventilation and blood flow through individual organs decrease, and the body´s performance and ability to ensure homeostasis of the internal environment are reduced. The performance of the immune system – is also of great importance for longevity - it protects the body not only from infections, but also from neoplasia. Influenceable factors that significantly determinte life expectancy are the quality of the environment and lifestyle.

Links[edit | edit source]

Sources[edit | edit source]

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