An introduction to the basic biology of aging
Ageing is an inherent aspect of life. We cannot live without ageing and yet in the end, it is why we must die. So, here is an introduction to the underlying cell biology – a subject to which I have personally contributed a large number of publications in the scientific/medical literature.
- Our cells – We all start life as one fertilised egg and this egg divides and those cells divide and so it goes on until a baby is born with trillions of cells. But while we start as one egg that is fertilised by one sperm, the egg itself is not uniform and as more and more cells result from the ongoing cell divisions, the cells end up in different regions of the egg. This early localisation confers different characteristics on the cells and commits them to very different roles in development and later function.
- Cell Division – The cell cycle, the cell division process in which genes and chromosomes are replicated, continues throughout life but most cells can only divide a limited number of times. The cell cycle primarily involves the replication of the DNA of each chromosome; the assembly of a spindle that will pull the chromosomes apart; the replication of the cytoplasm and all the other organelles it includes and MITOSIS, the major process and its stages prophase, metaphase, anaphase and telophase, in which the replicated chromosomes are split into two equal chromatids and two new ‘daughter’ cells are formed.
- Telomeres, Senescence & the Hayflick Limit – The end of each chromosome has a cap-like structure that is called a telomere that is composed of hundreds of repeats of a small specific sequence of DNA bases. Each time a cell divides, part of the telomere at each end of each chromosome is chopped off. When the telomere is chopped to its minimal length, known as the ‘telomere limit’, the cell stops dividing and either undergoes a process of cell destruction known as apoptosis or it becomes senescent.
- Senescent cells are inflammatory and whilst this is a major contributor to many of the diseases of ageing, the process of senescence occurs to protect against cancer. It’s what is commonly called ‘a double-edged sword’.
Dr Judy Ford, dressed in her Russian army uniform (supplied by the USSR and mandatory dress) at the congress held in Chernobyl for international experts (1991), 5 years after the radiation accident.
5. Many environmental factors contribute to health and longevity, among them nutrition, viruses and other infectious agents, radiation and chemical damage – which can all directly damage genes, chromosomes and telomeres as well the many and varied aspects of lifestyle.
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I am happy to give presentations on topics related to ageing. Please email me with your request.