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