BIOL 1090 Lecture Notes - Lecture 10: Pyrimidine, Transposable Element, Purine
2 Nov 2017
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Document Summary
Germinal mutations occur in germ-line cells and will be transmitted through the gametes to the progeny. Somatic mutations occur in somatic cells; the mutant phenotype will occur only in the descendants of that cell and will not be transmitted to the progeny: produces delicious apples. Spontaneous mutations occur without a known cause due to inherent metabolic errors or unknown agents in the environment. Induced mutations result from exposure of organisms to mutagens: physical and chemical agents that cause changes in dna, such as ionizing irradiation, ultraviolet light, or certain chemicals: molecular basis of mutation. Trinucleotide repeats: (repeats of 3 nucleotide pairs) can increase in copy number and cause increase in copy number of inherited diseases: mutagenesis, vast majority of spontaneous mutations arise randomly by mechanisms shown above. In contrast, induced mutations occur upon exposure to radiation or chemical mutagens: mutagenesis by ultraviolet irradiation. Cross-linking of adjacent thymine forms thymine dimers which block dna replication (activate dna repair mechanisms).
