bacterial genetics Flashcards
are bacteria diploid?
no, haploid
what is medium that wild-type bacteria can grow on?
minimal medium (carbon source, salt, minrals)
what can wild-type cells synthesise from minial medium?
vitamins, amino acids, carbs + nuceotides
what prevents growth on a minimal medium ?
a mutation that effects biosynthetic pathway
what does complete medium contain?
all amino acids, vitamins, nucloetides
where will cells carrying a mutation inactivating a biosynthetic plathway grow?
on a complete medium but not on a minimal medium
where will bacteria grow carrying a gene involved in a specific biosynthetic pathway?
on a minimal medium containting biosynthethetic priduct
what is auxotroph?
bactera carrying a mutation that cannot syntheise essential nutirents
what are phototrophs?
bacterial strains that are wild type for a particular niosynthetic pathway
what happens to gene transfer in davis-U tube?
genetic transfer cannot occur as in tube there is no direct contact between auxotroph cells
what is fertility factor?
(F+) circular DNA molecule taht allows carriers to conjugate wih F- recipient cells
what happens to F+ during conjugation?
it is replicated and copy is transferref through F pilus to F- recipient
how can high frequency combination strains cause host genes into F-?
F plasmid recombines with host DNA. INtegrated F can leave chromosome and carry host genes with it . which can then be copied and transferred into F- during conjugation
how can trancription of some genes be regulated?
by a sequence next to promoter region that a repressor can bind to , to prevent the trans[rt of RNA polymerase. . when repressor dissociates, rna polymerase can pass- induces transcription
what can enzymes coded by e.coli do?
break down lactose into glucose and galactose
wat is an operon?
group of tightly linked genes(adjacent) with closely related function, whose RNA is synthesized in one piece .
what is lac operon?
operon for breaking down lactose that is activated in response to lactose.
what does lac operon do?
encode proteins that cause lactose breakdown
how does lac repressor dissociate from operator?
it binds to lactose
how is lac operon inhibitung/?
glucose inhibits transcription by inactivating RNA polymerase co-factor (CAP protein)
how is trp operon/transcription repressed?
if high levels of tryptophan, transciption is repressed.
