MUTATIONS

=Mutations= A mutation is any permanent change to the sequence of bases in an individual’s genome. Small changes to the sequence of our coding regions (genes) can result in a protein that is non-functional or even toxic. We can think of a gene kind of like a recipe for a protein. Just like with any recipe, making small changes can be harmless. This is the case with alleles, slightly different sequences resulting in slightly different proteins that function in a slightly different way. However, they can be disastrous, sometimes even small changes to parts of the sequence result in a protein that simply does not work, or produces some unwanted product. [image:http://i.imgur.com/Dmk1gXz.jpg?1] '''The Effect of a mutation can be:''' *Silent *Deleterious *Lethal *Advantageous Most mutations are silent, this is because most of our DNA does not code for anything (‘empty pages in our recipe book’). However, any changes made to coding sequences or genes are almost always deleterious (bad). Most of the time the resulting protein simply does not work; if the individual still has one functioning version of the gene then they will not be affected (the mutation is recessive). Most mutations are recessive. However, if the resulting protein is toxic or produces something toxic the individual may be affected regardless of whether they have another functioning version or not (the mutation is Dominant). If the affected protein is essential for survival, the mutation is said to be lethal. Very rarely slight changes to a coding sequence can be advantageous. There is only one documented case in humans (an increased tolerance towards cholesterol found in a small Italian village) ==Three types of mutations== [image:http://i.imgur.com/yqs73lh.png?1]