Lab Exam Flashcards
(8 cards)
what is the advantage of antibiotic resistant genes in molecular microbiology?
-they can be used as selective markers in gene transfer experiments
-by growing them on selective media you can determine if the cells have the gene of interest
how does Rifampicin work?
-nucleic acid synthesis inhibitor
-binds to the beta subunit of RNA polymerase to inhibit RNA synthesis
-resistance typically develops from a mutation in the beta subunit so that rifampicin can no longer bind and block synthesis
-spontaneous mutation can occur, but it can be induced
what can increase mutation freqeuency?
-UV light
-disrupts DNA
why must you remove the lid before placing the petri plate in the UV crosslinker?
-UV is blocked by most plastics
-lid is placed separately inside to ensure that it does not get contaminated
what are resistant mutants? how can we grow them?
-are able to grow in the presence of something that would normally inhibit the growth of the wild type
-in order to grow you can add the inhibitory substance to a complex medium (LB)
what are the 3 kinds of mutants?
-resistant mutants
-carbon source mutants
-auxotrophs
what are carbon source mutants? how can we grow them?
-unable to use a carbon source that would normally be used by the wild-type
-they must be provided a different carbon source in the medium (or grown on LB which contains many different carbon sources)
-in order to verify a mutation we must work with a minimal medium (M9) that contains an added carbon source
what are auxotrophs? how can we grow them?
-unable to synthesize a growth factor that would normally be synthesized by the wild-type
-in order to grow it we must add the growth factor in question to a minimal medium (or grown on LB which contains all growth factors)
-in order to verify a mutation we must work with a minimal medium (M9) that lacks this growth factor but contains everything else it needs (carbon source)
