A mutation is a random modification of the information held by the genome by a modification of the amino-acids sequence. They naturally occurs in every organism, but some environmental and biological factors are known to increase the mutation rate. Those factors are called mutagens (age, radioactivity, toxins, sun rays….).
Then, a mutation may have an effect (good or bad) or not.
When it has an effect (enzyme lack, unfonctionnal cells, hormon or metabolite secretion increase, sensibility to some factors…), this effect can be positive or negative.
If it’s a positive one, the mutation holding organism have better chance to survive, so to breed and so give this mutation to his childs only if this mutation appears in all the body (means that occurs during fecondation or gametogenesis of his parents). And those childs will be betters, and will more breed etc.. and by the time, this mutation will spread all over the population.
If it’s a negative one, the mutation holding organism have less chance to survive, so to breed and so give this mutation to his childs. And those childs will be deficient, as the parent, and will breed less etc.. and by the time, this mutation will disappear in the population.
If this mutation has no effect, it will randomly spread all over the population.
So a mutation can be good or/and bad or simply none of those adjectives 🙂 Hope it helps you
