BIOL 102 Lecture Notes - Lecture 32: Chain Termination, Frederick Sanger, Immunodeficiency
Document Summary
Evolution decent with modification or, genetic change over time. The evolution of living organisms is the consequence of two basic processes: generation of genetic variability via continuous accumulation of new mutations within populations, changes in the frequency of alleles within populations over time. Mutations can occur because of errors in dna replication. Point mutation change in the nucleotides sequence of dna at one position: nucleotide substitution, deletion, insertion. They may be lost, maintained in the population as a polymorphism, or become fixed, displacing the ancestral allele. The fate of mutations that affect the fitness of their carrier is partially determined by natural selection (positive or negative) The fate mutations that have no fitness effects (neutral alleles with respect to slection) is determined by chance stochastic events (random genetic drift) Occur at a single nucleotide position (boxed) Sometimes correlate with risk of particular genetic disease.
