micro ch 14 LS module
two common motifs of the DNA binding domain of regulatory proteins are _____ fingers and _____ - _____ - helix
- zinc fingers - helix - turn - helix
the ara operon is under the regulatory control of the ____protein and the ____activator protein
-AraC -catabolite
which of the following are common motifs of the DNA-binding domains of regulatory proteins?
-Zinc fingers -helix-turn-helix
which conditions must be met for AraC to act as an activaor of the ara operon?
-arabinose must be present -two AraC proteins must bind to aral
which of the following statements about the inhibition of transcription by the lac repressor protein are true?
-binds to O1 and one additional lac operator site -bends to DNA in the promoter region
DNA-bound repressor proteins inhibit the initiation of transcription by ____?
-blocking the binding of RNA polymerase -preventing the movement of RNA polymerase
which of the following are characteristics of the AraC protein?
-can interact with three different regulatory sequences -can act as an activator -can bind arabinose -can act as a repressor
characteristics of the lac repressor protein
-each subunit contains a helix-turn-helix domain -composed of four identical subunits -forms a dimer
which of the following is not a component of bacterial operons? -structural genes -promoter -operator -regulatory genes -enhancer
-enhancer
which choices are steps where gene expression is commonly regulated in bacteria?
-feedback inhibition -transcription elongation -initiation of transcription -initiation of translation
which of the following statements about the interactions between the lac repressor and inducer are true?
-inducer binding causes repressor to lose ability to bind to the operator sites -inducer binding changes the repressor shape
which of the following are encoded by the lac operon?
-lacl -three structural genes
which of the following are possible components of a bacterial operon?
-operator -structural genes -promoter -activator binding genes
DNA bound repressors proteins inhibit the initiation of transcription by ____
-preventing the movement of RNA polymerase -blocking the binding of RNA polymerase
which of the following conditions must exist to fully induce the lac operon?
-shortage of preferred carbon and energy source -lactose present in the medium
which of the following are characteristics of the trp repressor protein
-synthesized in an inactive form -active form binds to operator -tryptophan acts as a corepressor
which conditions must be met for AraC to act as a repressor of the ara operon?
-two AraC proteins on different regulatory sequences must interact -Arabinose must be absent
the term used to describe the metabolic pathway that uses DNA as a template for the manufacture mRNA is called ____, and the pathway that uses mRNA as the template for the manufacture of protein is called _____.
1) transcription 2) translation
A repressor protein that is synthesized in its inactive form is referred to as a(n) ____
Aporepressor
what protein is responsible for binding the ara operon DNA in such a way to prevent RNA poly. from binding to the ara promoter
AraC
A(n) _____protein is a DNA-binding protein that promotes the initiation of transcription
activator
A(n) ____protein is a DNA binding protein that promotes the initiation of transcription
activator
AraC acts a(n)____of transcription initiation when two AraC-arabinose complexes bind to the aral regulatory sequences
activator
when ____proteins bind to their regulatory sites they facilitate the binding of RNA polymerase
activator
positively controlled inducible genes
activator protein is inactive; activated by an inducer
the sugar ____is the inducer of the lac operator
allolactose
the lac repressor protein inhibits transcription by ____?
bending DNA in the promoter region
which of the following is most likely to contain repressible enzymes?
biosynthetic pathways
which statement best describes the ara operon?
both negative and positive transcriptional control
which of the following is most likely to contain inducible enzymes?
catabolic pathways
the lac operon is under the regulatory control of the lac repressor protein, and the ____ ____ protein or CAP
catabolite activator
Aporepressors are activated by the binding of a(n) ___?
corepressor
the zinc finger DNA-binding domain are most commonly observed in the regulatory proteins of the domain ___?
eukaryotes
DNA-bound activator proteins promote the initiation of transcription by ____?
facilitating RNA polymerase binding
which of the following are encoded by the trp operon?
five structural genes
the term "regulation of ___expression" refers to the process of controlling transcription and/or translation
gene
constitutive genes:
genes that are expressed continuously
regulatory:
genes that are only expressed when needed
the catabolite activator protein functions in a regulatory network that allows E.coli to preferentially use _____over all other carbon and energy sources
glucose
enzymes that catalyze reactions that are in constant demand in a cell are encoded by genes referred to as?
housekeeping genes
what is the name given to the collection of genes that encode protein products that must that must be all the time?
housekeeping genes
the level of some enzymes, such as B-galactosidase, increase significantly in the presence of a small effector molecule called a(n):
inducer
small effector molecules whose presence increases the level of specific enzymes are called ____
inducers
enzymes whose level increases in the presence of small effector molecules are encoded by?
inducible genes
which proteins are regulators of the lac operon?
lac repressor catabolite activator protein
the arrangement of functionally related genes in bacteria is
lined up together on the same chromosome
___ ____ control occurs when the initiation of transcription is inhibited by the binding of a protein to DNA
negative transcriptional
which of the following terms indicates that the binding of a protein to DNA inhibits the initiation of transcription?
negative transcriptional control
which statement best describes the lac operon?
negative transcriptional control of inducible genes(i.e turned "off" until turned "on")
the trp operon is best described as a example of the?
negative transcriptional control of repressible genes
which of the following statements about bacterial genes expression is NOT true?
no partial or low levels of gene expression
the activity of regulatory proteins is typically influenced by what type of interaction with small effector molecules?
non-covalent binding
in bacteria, repressor proteins bind to a specific DNA sequence called the ___?
operator
Which statement about th trp operon is true
operon is functional when tryptophan is absent
which statemenet about the trp operon is true?
operon is functional when tryptophan is absent
Many regulatory proteins are DNA-binding proteins that form dimers and bind to short, inverted sequences of bases in DNA that are called
palindromes
short, inverted sequences of bases in DNA are called ____
palindromes
which of the following terms indicates that the binding of a protein DNA promotes the initiation of transcription?
positive transcriptional control
proteins that are responsible for the induction or repression of enzyme encoding genes are referred to as _____ proteins
regulatory
A(n) ____protein is a DNA binding protein that inhibits the initiation of transcription
reppressor
the genes that encode enzymes that have their expression levels decrease in the presence of the pathway end-products are best describes as?
repressible genes
A(n) _____protein is a DNA-binding protein that inhibits the initiation of transcription
repressor
negatively controlled inducible genes
repressor protein is active; inactivated by an inducer
proteins that inhibit the initiation of transcription by binding the DNA are called____
repressor proteins
genes that do not code for regulatory proteins are referred to as ____genes
structural
What term is used to describe non-regulatory genes?
structural genes
one of the ways the trp operon is regulated is that it is _____
synthesized in an inactive form
which of the following statements about functionally related structural genes in bacteria are true?
they are located next to each other on the chromosome they often produce a polycistronic mRNA
repressible genes
those genes that are "turned off" by the product of repressible genes
the trp operon is only active when ____ is not present in the cell
tryptophan