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WorksheetsBIOL-1240 Gene Expression-Operons Ch 16
Total questions: 25
Worksheet time: 15mins
Genes that code for the proteins that are constantly needed for survival of an organism are
promoters
constitutive genes
operons
repressor genes
always "on"
A repressor usually controls an inducible gene by
keeping it "turned off"
suppressing mRNA production
reducing product resulting from an active inducer
inducing an antagonist
blocking DNA replication at specific sites
The basic way(s) that cells control their metabolic activities is/are by
regulating enzyme activity
mutations
developing different genes for different purposes
controlling the number of enzyme molecules
transduction
The genes and genetic information in different cells of multicellular organisms are
all slightly different
distinctly different
identical in the same tissues, different in the different tissues
almost all identical
Replication in specific genes in cells that need more of them is an example of
magnification
amplification
induction
a positive control system
a regulon
(a) genes are genes that encode essential proteins that are in constant use.
The (a) is a sequence of bases that switches mRNA synthesis "on" or "off."
One would expect a gene involved in the manufacture of ATP to be
"off" usually
always "on"
facultative
a constitutive gene
sometimes "off", sometimes "on"
The tryptophan operon in E. coli is
usually on
on in the absence of corepressor
repressed only when tryptophan binds to repressor
an inducible system
a repressible system
The lactose operon in E. coli
contains three structural genes
is turned on by a repressor
is a repressor
is an inducible system
The operator of the lactose operon in E. coli is located
between the promoter and the TATA box
upstream of the promoter
between the promoter and the structural genes
among the structural genes
anywhere on the chromosome
How does the lactose repressor block transcription of the lactose operon?
by "turning off" the appropriate genes in the intron
by regulating the activity of the enzymes that the operon codes for
by binding allosterically to the appropriate genes
by slowing the uptake of lactose into the cell
by binding to the operator
The gene that codes for the repressor protein of the E. coli lactose operon is
located between the operator and the promoter
downstream from the promoter region
downstream from the operator
constitutive
turned off most of the time
The molecular switch that controls gene expression is known as
the operon
controller
the operator
repressor
inducer
Lactose induces the transcription of the lactose operon by
binding to the allosteric site of the repressor after being converted to allolactose
stimulating lactose metabolism in the cell
binding to the glucose operon, making it inoperable
binding to the allosteric site of RNA polymerase
inhibiting the activity of CAP
The inducer of the lactose operon in E. coli is
CAP
AMP
allolactose
glucose
galactose
Inducible genes are usually actively transcribed when
the molecule degraded by the enzyme(s) is present in the cell
repressor molecules bind to the promoter
lactose is absent from the cell
quantities of precursor materials are low
there is no other substrate that can be used by the cell
Repressible genes are usually actively transcribed when
repressor molecules bind to the promoter
the supply of the end product formed by the enzymes encoded by these genes is low
tryptophan accumulates in the cell
quantities of precursor materials are high
there is no other substrate that can be used by the cell
Refer to Figure 14-1. The area of the tryptophan operon labeled 3 is the
promoter
repressor gene
ribosome
RNA polymerase
operator
Refer to Figure 14-1. The structure labeled 7 in the figure of the tryptophan operon is
an active repressor protein
an inactive repressor protein
an active RNA polymerase
an inactive RNA polymerase
a ribosome
The promoter in Figure 14-1 is labeled _________
6
3
1
2
7
The rate of eukaryotic transcription after initiation is affected by
upstream promoter elements
groups of genes arranged into operons
the action of catabolite activator proteins
how fast caps and tails can be added to pre-mRNA
enhancers
A TATA box is seen in __________ cells and is the site where __________.
bacterial; RNA polymerase binds
eukaryotic; DNA ligase cleaves introns
eukaryotic; RNA polymerase binds
both bacterial and eukaryotic; transcription factors bind
bacterial; a repressor protein binds
Upstream promoter elements in eukaryotes are
nucleotide sequences that act as binding sites for RNA polymerase
nucleotide sequences that regulate the efficiency of transcription initiation
nucleotide sequences that contain the TATA box
proteins that enhance RNA polymerase binding to the promoter
proteins that inhibit RNA polymerase binding to the promoter
Eukaryotic enhancers are capable of which of the following EXCEPT ?
regulating a gene even if they are cut out of the DNA and reinserted inverted
regulating a gene from very long distances
interacting with proteins that regulate transcription
increasing the rate of RNA synthesis after initiation
decrease the rate of transcription
