Mutations
Mutation is a change in a genome.
Classification of mutations
What types of mutations are there?
- Large scale mutations (chromosome abnormalities):
- polyploidy: sets of chromosomes are duplicated
- amplifications or gene duplications
- deletions: loss of entire chromosomal regions
- chromosomal rearrangements:
- inversions
- translocations
- loss of heterozygosity: in diploid cells, we have two copies of each gene, somewhat different as inherited from parents; if we lose one, this is different from homozygosity which means identical two copies of a gene.
- Small scale mutations:
- insertions of nucleotides; results in frameshift
- deletions
- substitutions
- synonymous (same amino acid encoded)
- non-synonymous
- missense (different amino acid encoded)
- nonsense (premature termination)
Consequences of mutations for cancer
- mutations that cause uncontrolled growth and multiplication of cells
- and other mutations that block the normal defenses that protect against unnatural growth.