2007-02-12 23:48:41 · 6 answers · asked by jumbo lopez 1 in Science & Mathematics ➔ Biology
It only works this way when we are young and able to breed. As we age then the regenerating ability slows down and finally peters out. We are aging all the time when this happens.
2007-02-12 23:59:04 · answer #1 · answered by Gone fishin' 7 · 0⤊ 0⤋
Actually the body only regenerates some of its tissues. Some tissue is finite and just wears out. Also over time fewer and fewer cells are still regenerating as cells start losing their function. A lot of research in the area points to the telomeres of chromosomes having a certain length that protects the chromosomes of the cell for only few divisions before it starts losing it's length and eventually it is gone allowing the degradation of the DNA and the destruction of the cell.
This programmed cell death is a double-edged sword, because without it, the cells are immortal, and are, in fact, cancer.
2007-02-13 02:08:50 · answer #2 · answered by btpage0630 5 · 0⤊ 0⤋
Growth and repair are not perfect. For example brain cells do not normally divide but plaque can build up leading to Alzheimer's disease. Arteries harden due to plaque buildup that is not removed by cell division. When cells divide, the DNA is split in half and each new cell 'repairs' its half of the DNA but not always to perfection. And a small amount of DNA code may be lost at the ends of the DNA strands (like split ends?) limiting further satisfactory division, perhaps only 50 divisions. Certain cells such as hear muscle do not divide except to repair damage (surgeon's knife cuts?) while other cells are programmed to replace tissue often (skin and stomach lining and hair). You only get one clean slate but it is guaranteed to last a lifetime, especially if you keep it out of trouble and always care for it.
2007-02-13 00:37:52 · answer #3 · answered by Kes 7 · 0⤊ 0⤋
Apoptosis is genetically programmed cell death. Cells are programmed to only undergo mitosis so many times. Once that number is reached, no more mitosis, then the cells aren't replaced and eventually break down.
2007-02-13 00:15:54 · answer #4 · answered by Niotulove 6 · 0⤊ 0⤋
our DNA is programmed to age us. Everybody ages differently but there are genetic factors in how we age. Even though new cells are produced they are aging with us as the DNA is. (all women are born with x number of eggs and do not produce anymore...these age as the body ages and genetic material ages them..that is why over the age of 35 there are more risks to getting pregnant....it's the same idea) Our DNA ages with us and also is programmed to age us....(like when our hair will gray, when our skin will lose elasticity..etc.)
2007-02-13 00:05:37 · answer #5 · answered by kitten 3 · 0⤊ 0⤋
Natural selection seems to select us to reproduce offspring which reproduce as much as possible.
In theory, it may be possible to get around this impasse
2007-02-12 23:57:56 · answer #6 · answered by Sciman 6 · 0⤊ 1⤋