Mutations have worked hard over the last few millennia to turn us from bacteria into complex sentient life forms capable of writing on a world-wide electronic net.
The basics.
And for all that hard work they usually only get press only when we hear about cancers and genetic diseases, but they can not be all bad; lets not forget that we are who we are today because of them.
If a mutation was inherited from either you father’s sperm or your mother egg it is a hereditary mutation.
A somatic mutation occurs in body cells and can not be inherited because the genes in the faulty cell have nothing to do with the sex cells.
With both types of mutations the chances of having a one increase with age because of the natural increase in errors that replicating DNA has. There is so much DNA to replicate that the few that do occur add up. The chances of giving birth the a child with Down’s syndrome are
Hereditary mutations.
Hereditary mutations can sometimes be so severe that they cause the
Each cell needs instructions telling it how to act. Every cell in the body has the same genes, it is the active genes that keep the cell different (a brain cell a brain cell and not a blood cell). A woman has two X chromosomes, but one is turned off, is this a hereditary mutation? No, it is an example of the next type of mutation:
Somatic mutations.
Which X- chromosomes should be inactivate? Depends on the cells personal choice. X- inactivation occurs after the embryo has divided a few times; if the X-inactivation had occurred when there was only one cell then all the cells would be the same, but the delay means that all women are a mix of maternal and paternal X-chromosomes in their bodies. This can be seen graphically in red and black tortoise-shell coats of some cats.
A somatic mutation is something that has developed in your body and is not inheritable. An example of this is cancer (only a vulnerability to cancer can occur through genes). The cells of the human body are designed to work together co-operatively so they try to resist cancers themselves as well as being removed by the immune cells. How do cancers develop if the body fights them?
When DNA is replicated in cells during the natural process of repair and maintenance mistakes in the copying process occur; this is the basis of both types of mutations. Cells in the gut are removed (by apoptosis) and replaced every three days; this is a high division rate in cells and all that DNA copying needs to be done accurately. Around 3 mistakes are made in each cell after each division. (Amazing when you think that there are 10, 000, 000, 000 bases being copied.) The reason for the few mistakes is that the DNA makers have a proof-reading ability and can spot a mistake.
The odd mistakes may be missed, or created in the cell from mutagens, such as UV-light in the skin, or smoke in the lungs. These mutations do add up and as the DNA codes for all cell components it is only a matter of time before a vital component is structurally altered too much to work. If a cancer suppressor is damaged or inactivated then the cell takes one step towards becoming dangerous.
At this point the cell either spots the fatal error and dismantles itself, the immune system kills it or, if the cell is so mutated it can’t die, or the immune system still thinks it looks normal, it becomes cancerous.
As the cells grow and divide more mutations are made giving the cancer extra-abilities: they need more oxygen so they release factors that bring blood vessels to them; they move into the blood and grow in another part of the body. This is bad for the host.
The number of mutation increase with time; that is why cancers are commonly a disease associated with old age.
Mutations are a trial-and-error process that may help or hinder, but they make us who we are and are part of a natural process going back a very long way.
family is prone to a particular type of cancer this cancer has an inherited component and waits for a cell in the body to make a mistake. For example; if many women in you family have breast cancer then it suggests that a gene is damaged in the family instructions, but if your instructions came for the other side of the family the risk may be reduced (depending on the type of breast cancer).about 1 in 1529 for a 20-year-old and 1 in 112 for a forty-year-old. foetus to abort, but they are not always life-threatening and some can provide an advantage: science has been looking for intelligence genes for years.
