Chapter Eighteen: Gene Regulation in Prokaryotes Flashcards
bacteria are ___ and ___ their environment
in contact with and respond to
the ability to coordinate the expression of many genes leads to ___ and ___
survival and energy savings
luminescent bacteria protect squid from predators by controlling the ___
light level to match the moonlight
___ of ATP being used does into protein synthesis, don’t want to ___ when its not necessary
80%
make protein
___ participates in all three phases of prokaryotic transcription
RNA polymerase
in transcription initiation, RNA polymerase has four subunits (___, ___, and ___); ___ binds to RNA polymerase and recognizes the promoter site and also binds to it
two alpha, one beta, and one beta prime
sigma factor
in transcription elongation, RNA polymerase is not bound to ___, but moves along DNA until ___
sigma factor
it reaches a termination sequence
there are two kinds of termination in bacteria: ___ and ___
rho-dependent and rho-independent
in rho-dependent termination, ___ binds to RNA polymerase and ___
rho protein
removes it from RNA
in rho-independent termination, RNA forms a ___
hairpin loop
transcription and translation occur ___ in prokaryotes
simultaneously
sequences for start and stop of transcription are ___ from sequences for start and stop of translation
distinct
mRNA are often ___, meaning multiple genes together can be controlled by one promoter
polycistronic
three levels of transcriptional control
- binding of RNA polymerase to promoter
- shift from initiation to elongation
- release of mRNA at termination
three levels of posttranscriptional control
- stability of mRNA
- efficient of translation initiation
- stability of polypeptide
in a catabolic pathway, molecules are ___
broken down
catabolic pathways require ___
inducible regulation
inducible regulation means that the pathway is ___ when ___
only turned on when molecules to be broken down are present
in an anabolic pathway, molecules are ___
built from simpler constituents
anabolic pathways require ___
repressible regulation
repressible regulation means that the pathway is ___ unless the cell ___
turned off
needs more of the larger molecule
utilization of lactose by E. coli provides a model system of ___
gene regulation
two enzymes required for lactose utilization
permease and beta-galactosidase (B-gal)
transports lactose into cells
permease
splits lactose into glucose and galactose
beta-galactosidase
lactose is a disaccharide of ___ and ___
glucose and galactose
are permease and B-gal present when lactose is not present
yes, in very low levels
lactose is an ___ of the genes encoding permease and B-Gal
inducer
stimulation of the synthesis of a specific promoter
induction
molecule responsible for induction
inducer
lac- mutants can be maintained on media with ___, so lac genes are not ___ for survival
glucose
essential
if both glucose and lactose are present, E. coli cells will use ___ first; if there is a lot of ___ present, lactose does not need to be ___
glucose
glucose
broken down
lactose induces a ___ increase in B-gal activity
1000 fold
studies of lac mutants revealed the ___ of gene regulation
operon theory
one signal can simultaneously regulate expression of several clustered genes
operon theory
three structural genes in the lac operon
lacZ, lacY, and lacA
site to which RNA polymerase binds
promoter
controls transcription and translation
operator
in the absence of lactose, a ___ binds to the ___ and functions to ___
repressor protein
operator
prevent transcription
the lac repressor is a ___ regulatory element
negative
when lactose is present, it binds to the ___, which moves off of the ___ because it ___; this allows for ___
repressor protein
operator
changes shape
transcription of the structural genes
type of repressor that reversibly changes shape and cannot bind to operator
allosteric repressor
when lactose is bound to the repressor protein, RNA polymerase binds to the ___ and initiates ___ of the ___ lac mRNA
promoter
transcription
polycistronic
lacZ encodes ___
B-galactosidase