Chapter 16 - BIO 326
cis-acting
A DNA segment that must be adjacent to the gene(s) it regulates is a ________ - _____ element
repressor : activator
A corepressor is a small molecule that binds to a ____ protein, thereby causing the protein to bind to the DNA, while an inhibitor binds to an ______ protein and prevents it from binding to the DNA
activator
A regulator protein that increases the rate of transcription is a(n) _____________
allosteric
A regulatory site on a protein where an effector molecule binds is called a(n) ___________ site
Prevents the repressor from binding to DNA
Allolactose is a small effector molecule that binds to the lac repressor and facilitates the repressor binding to DNA increases the affinity of the repressor for CAP Prevents the repressor from binding to DNA prevents the repressor from binding to RNA polymerase
polycistronic
An operon encodes a _____ mRNA, an RNA that contains the sequences of two or more genes
are unregulated
Constitutive genes respond to lactose levels in the cell are unregulated are regulated by glucose levels respond to amino acid levels in the cell
The rate of transcription initiation
In bacteria, the most common way to regulate gene expression is by influencing the rate of transcription initiation the rate of transcription elongation the rate of translation initiation the frequency of cell division
Gluose
In catabolite repression, transcription is influenced by the presence of galactose glucose fructose lactose
catabolic
Inducible operons usually encode _ enzymes
Anabolic
Repressible operons usually encode _________ enzymes
lacZ lacY lacA
Select all of the following that are protein-encoding genes in the lac operon lacO lacZ lacX lacY lacA
E D C B A
Select the genes in the trp operon Y E B C A D Z
Metabolism Cell division Response to environment
Select the processes that are regulated at the genetic level motility cell division response to the environment metabolism
lacI
The _____ gene encodes a repressor protein lacP lacA lacZ lacO lacI
allolactose
The intracellular concentration of the inducer _____ remains high as long as lactose is available in the environment
Regulation
The phenomenon in which the level of gene expression can vary under different conditions is gene_________.
corepressor
The product of an operon may act as a(n) _______ if the operon is repressible
Glucose; decrease
The transport of ______ into a cell causes a ________ in the concentration of cAMP by inhibiting adenylate cyclase tryptophan; increase allolactose; increase glucose; decrease lactose; decrease
negative
Transcription regulation by a repressor protein is considered to be _______
positive
Transcription regulation by an activator protein is considered to be _____ control
Constitutive genes
What type of genes encode proteins the bacterial cells needs all the time Riboswitches Constitutive genes Repressor genes Activator genes
transcribes the structural genes of the operon
When four molecules of allollactose are bound to the lac repressor, the lac operon is induced, and RNA polymerase transcribes more slowly transcribes the structural genes of the operon Is blocked from transcribing any genes binds to the operator
Catabolite activator protein - CAP site Repressor - operator RNA polymerase - Promoter
Which protein binds to which site Protein: Catabolite activator protein Repressor RNA polymerase Site: Operator Promoter CAP site