Lecture 16 - HMB265: Human & General Genetics Lecture 16:...

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HMB265: Human & General Genetics Lecture 16: Mutation Prof. Maria Papaconstantinou
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Lecture Outline DNA mutation Consequences of mutation Use of mutations to determine enzyme pathways Reading: Griffiths et al ., 10 th edition, Chapter 16 ( emphasis on pages 553-558 and pages 560-567 ).
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Mutations are the source of new alleles Mutation is the process whereby genes change from one allelic form to another. The creation of entirely new alleles can occur. Genes mutate randomly , at any time and in any cell of an organism. Can arise spontaneously during normal replication, or can be induced by a mutagen . Only mutations in germ-line cells can be transmitted to progeny. Somatic mutations can not be transmitted. Inherited mutations appear as alleles in populations of individuals.
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General observations of mutation rates Mutations affecting phenotype occur very rarely Different genes mutate at different rates Rate of forward mutation is almost always higher than rate of reverse mutation Mutation can occur during normal DNA replication Mutation rate can increase after exposure to a mutagen (a mutation inducer, e.g. UV light, certain chemicals)
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Classification of mutations by effect on DNA molecule Hartwell et al. (2007) Genetics: From Genes to Genomes Substitution – base is replaced by one of the other 3 bases Deletion – block of one or more nucleotide (base) pairs is lost Insertion – block of one or more nucleotide (base) pairs is added Inversion – 180 rotation of a segment of DNA Reciprocal translocation – parts of 2 nonhomologous chromosomes change places Wild-type - starting sequence indel muta- tions
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DNA Structure purine pyrimidine
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Classification of mutations (cont) Base Substitution transition • A G (purine purine) (A·T G·C)
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This note was uploaded on 04/03/2012 for the course HMB 265 taught by Professor French during the Fall '09 term at University of Toronto- Toronto.

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Lecture 16 - HMB265: Human & General Genetics Lecture 16:...

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