Some mutations may change only one nucleotide what changes the codon into STOP codon, so that protein translation will be ceased earlier and inacurate or biologically useless peptide will arise in result.
Sometimes mutation causes change of one amonoacid. That one improper amonoacid may have negative consequentions for peptide (or protein) structure and eventually cause diorders. Such mutation is a reason for sickle-cell disease. It needs one aminoacid, valine to be translated, instead of glutamic acid (in 3rd position of beta haemoglobin chain) in order to change one’s life.
I am sure every biological book with topic about DNA or genes contains information you need. There is also a lot of information about mutations in the Internet, so please make some effort to find them 😉 .

Remember one thing That this dosent mean that mutations are directly accepted in genome, mostly mutated fragments of DNA are sliced off and repaired to restore original one.

If massive mutation occured that may become cureless, can not be repair.

http://www.genetichealth.com/G101_Changes_in_DNA.shtml
http://gslc.genetics.utah.edu/units/dis … tionbg.cfm

I think this link can help u!