ch 14 gene regulation in bacteria Flashcards
gene regulation
the phenomenon in which the level of gene expression can vary under different conditions
constitutive gene
a gene that is not regulated and has essentially constant levels of expression over time
repressor
a regulatory protein that binds to dna and inhibits transcription
activator
a regulatory protein that binds to dna and increases the rate of transcription
negative control
transcriptional regulation by a repressor protein
positive control
transcriptional regulation by an activator protein
inducer
a small effector molecule that binds to a repressor or activator and causes the rate or transcription to increase
inducible gene
a gene that is regulated by an inducer, which is a small effector molecule that causes the rate of transcription to increase
corepressor
a small effector molecule that binds to a repressor protein, thereby causing the repressor protein to bind to dna and inhibit transcription
inhibitor
a small effector molecule that binds to an activator protein, preventing the protein from binding to the dna and thereby inhibiting transcription
repressible gene
a gene that is regulated by a corepressor or inhibitor, which are small effector molecules that cause the rate of transcription to decrease
enzyme adaptation
the phenomenon in which a particular enzyme appears within a living cell only after the cell has been exposed to the substrate for that enzyme
operon
an arrangement in dna in which two or more genes are found within a regulatory unit that is under the transcriptional control of a single promoter
polycistronic mrna
an mrna that is transcribed from an operon and encodes two or more proteins
promoter
a sequence within a gene that initiates transcription
terminator
a sequence within a gene that signals the end of transcription
CAP site
a dna sequence that is recognized by the activator protein cap
catabolite activator protein (CAP)
a genetic regulatory protein found in bacteria
operator site
(also called operator) a sequence of nucleotides in bacterial dna that provides a binding site for a genetic regulatory protein
lac repressor
a protein that binds to the operator site of the lac operon and inhibits transcription
induced
refers to a gene that has been transcriptionally activated by an inducer
allosteric regulation
the phenomenon in which a small effector molecule binds to a noncatalytic site on a protein and causes a conformational change that regulates the protein’s function
allosteric site
the site on a protein where a small effector molecule binds to regulate the function of the protein
merozygote
a partial diploid strain of bacteria containing F’ factor genes
trans-effect
an effect on gene expression that occurs even though two dna segments are not physically adjacent to each other; mediated by diffusible genetic regulatory proteins
trans-acting factor
a regulatory protein that binds to a regulatory element in dna and exerts a trans-effect
cis-acting element
a sequence of dna, such as a regulatory element. that exerts a cis-effect
cis-effect
an effect on gene expression due to a genetic sequence within the same chromosome and often immediately adjacent to the gene interest
catabolite repression
the phenomenon in which a catabolite (ie glucose) represses the expression of certain genes (ie lac operon)
diauxic growth
the sequential use of two sugars by a bacterium
cyclic-amp
(also called cAMP) in bacteria, a small effector molecule that binds to cap; in eukaryotes, camp functions as a second messenger in a variety of intracellular signaling pathways
attenuation
a mechanism of genetic regulation, seen in the trp operon, in which a short rna is made but its synthesis id terminated before rna polymerase can transcribe the rest of the operon
trp repressor
a protein that binds to the operator site of the the trp operon and inhibits transcription
attenuator sequence
a sequence found in certain operons (ie trp operon) in bacteria that stops transcription soon after it has begun
posttranslational
describes events that occur after translation is completed
posttranslational regulation
the functional control of proteins that are already present in the cell
translational regulatory protein
a protein that regulates translation
translational repressor
a protein that binds to an mrna and inhibits its ability to be translated
antisense rna
an rna strand that is complementary to a strand of mrna
feedback inhibition
the phenomenon in which the final product of a metabolic pathway inhibits an enzyme that acts early in the pathway
allosteric enzyme
an enzyme that contains two binding sites: a catalytic site and a regulatory site
posttranslational covalent modification
the chemical alteration of a protein or the covalent attachment of a molecule or functional group to a protein after it has been synthesized via ribosomes
riboswitch
a mechanism for regulating transcription, translation, rna stability, and splicing in which an rna molecule can switch between two secondary conformations based on whether or not a small molecule (like tpp) binds to rna
antiterminator
a secondary structure in rna that prevents early transcriptional termination
