1) Expression of genes that are constitutive is:
a) regulated by repression.
b) unregulated.
c) regulated by induction.
d) regulated by activation.
e) regulated by attenuation.
3) What is an effector molecule?
a) A protein that binds to an operator region of a gene.
b) An activator protein for gene expression.
c) A small RNA molecule that inhibits translation of mRNA.
d) A small molecule that binds to an enzyme to regulate its activity.
e) A small molecule that binds to the operator region of a gene.
5) What is the function of methyl-accepting chemotaxis proteins (MCPs)?
a) To phosphorylate CheY.
b) To control the direction of flagellar rotation.
c) To dephosphorylate CheY.
d) To sense the presence of a specific chemical.
e) To drive the flagellum motors.
6) What would characterize the phenotype of a CheY mutant?
a) Loss of motility.
b) Constant tumbling.
c) Smooth swimming.
d) Inability to sense certain chemicals.
e) Movement toward repellents and away from attractants.
9) Which of these is required for transcription that is regulated by positive control?
a) activator protein
b) repressor protein
c) inducer protein
d) attenuator protein
e) DNA polymerase.
10) Which of these controls the expression of the lac operon?
a) An activator protein only.
b) An attenuation mechanism.
c) A repressor protein only.
d) Both repression and activation mechanisms.
e) Both repression and attenuation mechanisms.
11) How will E. coli growing in a medium containing both lactose and glucose react?
a) By preferentially utilizing lactose first.
b) By preferentially utilizing glucose first.
c) By utilizing both at the same time.
d) Neither compound will be utilized for growth.
e) One will sometimes be utilized over the other.
7) Which of these is typically involved in a two-component regulatory system?
a) Histidine kinase and a response regulator.
b) Repressor protein and an activator protein.
c) Repressor protein and a co-repressor.
d) An activator protein and a co-activator.
e) A repressor protein and an inducer.
18) Which component of the two-component regulatory system frequently senses changes in the
external environment?
a) repressor protein
b) activator protein
c) histidine kinase
d) response regulator
e) transport protein
20) How is quorum sensing, a type of cell to cell communication, mediated?
a) By direct cell contact.
b) By transfer of genetic information.
c) By chemical signaling.
d) By two-component regulation.
e) By an induction mechanism.
21) Which autoinducer is used by many Gram-negative bacteria?
a) a homoserine lactone derivative
b) an activator protein
c) a repressor protein
d) a metabolic intermediate
e) allolactose
23) The term for a large group of genes whose expression is under the control of a single
regulatory system.
a) operon
b) super operon
c) regulon
d) transcriptome
e) biome
24) What is a “reporter gene”?
a) A gene that is expressed under adverse environmental conditions.
b) The fusion of two different structural genes.
c) The fusion of a gene of interest to a regulatable promoter.
d) The fusion of a promoter region of interest to a gene whose product can easily be measured.
e) A gene whose product can easily be measured.
26) The catabolite activator protein (CAP) activates transcription of the lac operon when it binds
this coactivator.
a) lactose
b) glucose
c) cyclic-AMP
d) ATP
e) allolactose
27) What does sigma factor helps the RNA polymerase do?
a) Assemble tRNA subunits.
b) Bind to activator proteins.
c) Attach the ribosomal subunits.
d) Identify the promoter region of a gene.
e) Release from the transcribed DNA.
5. A student has isolated, from chocolate, a bacterial species which synthesizes a compound that acts as a
human pheromone. Smelling money, our young scientist patents the following sequence:
5’-CTGATGGAGGATTCTGGATGTATCTGGTGTGAAATT-3’
This sequence encodes a protein pheromone which is 4 amino acids long and the sequence corresponds to
the non-transcribed strand of the gene.
A. Write the transcribed strand in the 5’-->3’ direction.
B. Write the sequence, in the 5’-->3’ direction, of the message assuming the whole sequence above is
transcribed.
C. What is the amino acid sequence of the protein product? (Hint--don't forget about the Shine Dalgarno
sequence!!)
6. What are the roles of the following proteins/enzymes in the synthesis of macromolecules?
A. DNA ligase
B. Sigma factor
C. Primase
D. DNA Pol III
E. Topoisomerase
F. DnaA
G. Gyrase
7. Using a the table in your book which shows the genetic code, list the sequence of a mRNA that would
encode the following peptide: Met-leu-tyr-trp-val-asp-gln-gly-gly-stop.
8. Suppose you want to make a mutant of E. coli which is resitant to a new antibiotic. You know that the
antibiotic binds and activates a protein which is 100 amino acids long. If you mutate the gene for this
protein, the antibiotic is no longer effective. After mutagenizing a culture of E. coli, you plate one million
cells on a plate containg the antibiotic and 45 colonies grow. What was the mutation rate of the
mutagenized culture? Your answer should be in the units “mutations per base pair”.
11. The bacteriophage lambda chromosome has 1.2 x 10 5 bases. How many proteins could be coded by
this, assuming a molecular weight of 40,000 daltons/protein and 100 daltons/amino acid?
12. Define the following:
Gene
Transcription
Operon
Shine Dalgarno sequence
Aminoacyl tRNA synthetase
Promoter
Operator
Cistron
Polycistronic
Translation