mutations

• gene mutations involve a change in the DNA base sequence of chromosomes
• substitution mutation - one base is substituted with another
• deletion mutation - one base is deleted
• the order of DNA bases in a gene determines the order of amino acids in a particular protein. if a mutation occurs, the sequence of amino acids it codes for (and protein created) could be altered
• degenerate nature of genetic code means some amino acids are coded for by multiple DNA triplets, so not all substitution mutations have an effect as they'll still code for same amino acid
• deletion mutations always lead to changes in the amino acid sequence - changes number of bases so shifts all base triplets after it
• mutagens increase the rate of mutation - ultraviolet radiation, ionising radiation, and some chemicals
• mutations can occur randomly, ie. when DNA is misread in replication