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Picture from http://www.buildinggreentv.com/node/7088 http://steveaoki.dimmak.com/blog/2009/11/useless-information-4-bacteria/ http://www.scienceclarified.com/As-Bi/Bacteria.html
•Repressor binds to operator blocks transcription. •Corepressor binds to the repressor alters its shape enabling the repressor to bind to the operator. Transcription OFF!
•Inducer binds to the repressor alters its shape preventing the repressor to bind to the operator. Transcription ON!
-One or more amino acid is changed as a result. Bases (nucleotides) are changed or substituded-may be induced by radiation or chemical(mutanogens).
-Mutations can have a significant effect on genetic diversity.-New traits acquisition of resistance can be transmitted to other microbes.-Antimicrobial (Drug) Resistance
MutagensMutagens -Chemicals or radiation that changes the genetic material induced mutation• Base analogs -incorporated into DNA replace normal base with base analog(similar base) Base substitution• Intercalating agents -inserted(intercalated) b/w base pairs replace normal base with base analog -Frame shift mutation addition or subtraction of base pairs• Transposons -Random insertion into any gene. The gene inactivated. -Common in lab.
Ames test Ames test -uses bacteria to test chemicals…. “Is this chemical mutagen? Carcinogens?”-more rapid and inexpensive-More colonies than control plate (than normal) “This is mutagen!”