3.8.1 DNA + Structure of Proteins

which part of the cell cycle are mutations likely to occur?

during interphase where DNA replication takes place

gene mutation

any change to the quantity or sequence of DNA in an organism that occurs spontaneously

types of mutations

addition, deletion, substitution, inversion, duplication, translocation

-addition + deletion result in frameshift

impact of mutations

-non-sense mutation = a base change that results in a STOP codon in mRNA (UAA, UAG, UGA)

-mis-sense mutation = base change resulting in different amino acid being coded for → changes hydrogen bonds so alters tertiary structure so different/non-functional protein formed

-silent mutation = base change occurs but same amino acid still coded for → due to degenerate genetic code

advs + disadvs of mutations

useful = creates genetic diversity, provides ‘selective advantage’

not useful = prevents cell repair, prevent gamete production, switch on oncogenes

mutagenic agents

factors that increase rate of mutations

-smoking (benzopyrene), increased alcohol, radiation (UV + x-ray)