Debate and discussion of any biological questions not pertaining to a particular topic.
4 posts • Page 1 of 1
Or; what is the mechanism of the reproductive system's expemption from cellular 'copy imperfection'/aging - so that all parts of our bodies will replace cells with increasingly imperfect copies except those pertaining to offspring?
I do not think you and your perception are entirely wrong.
That being said, even the reproductive system ages; I think that is one reason why the children of older women have more birth defects and why the fertility of men decreases over time (although most men stay fertile for most of their lives).
However, there is a mechanism to prevent 'aging' in certain cells in the body, for example in blood cell progenitors and other stem cells or stem-cell-like cells. Similar mechanism is probably at work also when it comes to the cells of the germ line. There is also another mechanism in action and it is called natural selection: the embryos generated by healthy sperm and egg cells are more likely to develop into a human that survives to reproductive age - most of the embryos with noticeable 'copy imperfection' (I assume you mean harmful mutations by this) do not survive to become human beings but are miscarried instead, or if they make it through the pregnancy and become little baby boys and girls still do not survive to reproduce themselves.
I think what you asked is an interesting question and the answer to that may involve some other factors than what I mentioned. Anyway, there are many lower organisms who seem to be more than capable of withstanding the increase of imperfection in their genomes - bacteria, for example, can divide virtually indefinitely if they just have food and room, and you do not see them 'dying of old age'. Since their cellular processes cannot remove every single harmful mutation, I believe the most important factor is the natural selection, where bad copies die off and the good ones keep going. With viruses we see that you can actually have a horribly bad fidelity in your copying machinery and it becomes your advantage (in the form of drug resistance or immune system evasion) if you just manage to produce enough copies of yourself.
(Actually, the first ever organism that gave rise to the life on Earth has fought entropy successfully ever since, as an unbroken chain that has evolved into such weird things as you or I, or bacteria.)
4 posts • Page 1 of 1
Who is online
Users browsing this forum: No registered users and 7 guests