Mutation

Gene mutations - Changes in one or more nucleotide bases, or in the sequence of bases

Point mutations:

• Only changes one nucleotide at a time, leading to maximum one amin acid change

Silent mutation:

• Results in the same amino acid being produced, so no outward change

Frameshift mutation: A base is either added (addition) or removed (deletion)

• Every subsequent triplet is shifted along

Nonsense mutation: A codon changes to a STOP codon

• Leads to a shortened protein being produced

Missense mutation

• A DNA change that results in different amino acids being encoded at a particular position in the resulting protein

Chromosome mutations

Changes in whole set of chromosomes

• When organisms have three or more whole sets of chromosomes rather than 2

  • Polyploidy happens mostly in plants

• Hybridisation cross species fertalistion

Change in the number of individual chromosomes

• Homologous pairs of chromosmes fail to seperate during meisos

• Causes one more, or one fewer chromosomes

• E.g. Downs syndrome of Klinefelter