What Are Mutations? A change in the structure or amount of an organism’s genetic material When a change in genotype produces a change in phenotype, then the mutation is apparent
What Are Mutations? Changes in the nucleotide sequence of DNA May occur in somatic cells (aren’t passed to offspring) May occur in gametes (eggs & sperm) and be passed to offspring
Frequency of Mutation In the absence of outside influences, gene mutations arise spontaneously. Mutation rate varies from species to species, allele to allele. Most mutant alleles are recessive- expressing themselves when two recessive alleles meet in future generations.
Are Mutations Helpful or Harmful? Mutations happen regularly Almost all mutations are neutral Chemicals & UV radiation cause mutations Many mutations are repaired by enzymes
Are Mutations Helpful or Harmful? Some type of skin cancers and leukemia result from somatic mutations Some mutations may improve an organism’s survival (beneficial)