BIOL240 Lecture Notes - Lecture 30: Esther Lederberg, Replica Plating, Auxotrophy
15 Mar 2019
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Replica plating with pro+ and pro- plates. In general, dna replication occurs without much error but mistakes can occur: mutations aren"t always bad as they can further evolution, they alter the coding portion of a gene, sometimes resulting in an aberrantly. Types of mutations functioning protein: silent no change in sequence, usually third position change of codon, missense one aa is changed in the sequence. May have no change or effects may be positive or negative: nonsense stop codon coded for early, frameshift the result of insertion or deletion of nucleotides, changing how a ribosome. Used replica plating to illustrate spontaneous mutation without selective pressure. Hence mutations occur randomly and not when exposed to a selective stimulus. Variable resistance to phage infection arises in bacteria without selective pressure bacterial cultures will evolve in a test tube if they are kept there with the right conditions for a long time.
