Bio 221 Microbiology
Exam 2
Name _______________________
Matching
Match the following metabolic pathway with the key diagnostic enzyme for the
presence of the pathway. (1 point each)
___
___
___
___
___
___
Entner-Duodoroff Pathway
Calvin Cycle
Wood-Ljungdahl Pathway
Reverse TCA cycle
Hexose monophosphate shunt (Pentose phosphate pathway)
Glyoxylate shunt
A.
B.
C.
D.
E.
F.
CO dehydrogenase
Fumarate reductase
Ribulose bisphosphate carboxylase
6-Phosphogluconate dehydrogenase
KDPG aldolase
Isocitrate lyase
Match the following types of plasmid vectors and their characteristics. (2 points
each)
___
___
___
___
broad host range vector
suicide vector
shuttle vector
cloning vector
A. Contains origins of replication that enable the plasmid to replicate in
bacteria and human cells.
B. Contains an origin of replication this is very specific and the plasmid will
not replicate in the recipient cell.
C. Contains special features for inserting new genes and/or expressing their
gene products.
D. Contains an origin of replication that is able to replicate in more than one
species of bacteria.
Multiple Choice (1 point each)
____ Which of the following is NOT a source of electrons for anoxygenic
photophosphorylation?
A.
B.
C.
D.
E.
Hydrogen sulfide
Thiosulfate
Succinate
Water
Hydrogen gas
____ Which of the following sequences of types of organisms accurately reflect the
order in which these types of organisms are found in a microbial mat (from top to
bottom)
A. Cyanobacteria, purple non-sulfur bacteria, purple sulfur bacteria, green sulfur
bacteria
B. Green sulfur bacteria, purple sulfur bacteria, purple non-sulfur bacteria,
cyanobacteria
C. Cyanobacteria, green sulfur bacteria, purple non-sulfur bacteria, purple nonsulfur bacteria
D. Purple non-sulfur bacteria, purple sulfur bacteria, green sulfur bacteria,
cyanobacteria
____ Why is it necessary for phototrophs to make NAD(P)H?
A.
B.
C.
D.
for
for
for
for
biosynthesis
electron transfer phosphorylation
fermentation
the Krebs cycle
____ Which of the following key biosynthetic precursors is NOT generated either
through the Embden-Myerhoff-Parnas Pathway or the Entner-Duodoroff pathway?
A.
B.
C.
D.
E.
Glucose 6-phosphate
Phosphoenolpyruvate
Pyruvate
3-Phosphoglycerate
-Ketoglutarate
____ What is an anapleurotic reaction?
A. A reaction that occurs in more than one pathway.
B. A reaction that can proceed in either the forward or reverse direction?
C. A reaction that is exactly the opposite of a reaction catalyzed by a different
enzyme.
D. A “replenishing” reaction that provides an alternative mechanism to generate
key intermediates “lost” due to biosynthetic reactions.
____ Which of the following families of amino acids require -Ketoglutarate as a
precursor?
A.
B.
C.
D.
E.
Glu, Pro, Gln, Arg
Asp, Lys, Asn, Met, Thr, Ile
Ala, Val, Leu
Ser, Gly, Cys
Trp, Tyr, Phe
____ What is the function of chaperone proteins?
A. Assisting protein secretion by keeping polypeptides from folding prematurely.
B. Binding to signal peptides and guiding them to their target in the cell membrane.
C. Cleaving the signal peptide after secretion of the polypeptide through the cell
membrane.
D. Guiding mRNAs to the appropriate ribosomes.
____ Why is cellulose a poor nutrient source for humans and most non-ruminant
animals?
A.
B.
C.
D.
It’s bonds are difficult to break.
It is only made from one sugar.
It is inaccessible through cell wall
It is complexed with membrane.
____ Why are biodegradable plastics biodegradable?
A.
B.
C.
D.
Made thinner.
Made from biological material.
Special bacteria break them down.
Made of water soluble material.
____ If you wanted to cleave a protein into smaller, specific polypeptides for analysis,
which type of enzyme should you use.
A.
B.
C.
D.
peptidase
endopeptidase
carboxypeptidase
aminopeptidase
____ Which of the following enzymes is involved in the break down of starch?
A.
B.
C.
D.
Starchase.
Gluconase
Acetase.
Amylase.
____ When studying gene expression, Why do investigators typically use reporter gene
fusions in which the promoter for their gene of interest is linked to a gene encoding an
enzyme such as beta-galactosidase or a protein such as green fluorescent protein.
A. the reporter gene is smaller than the original gene so it is easier to control
than the original gene.
B. the reporter gene codes for an enzyme that is easier to detect (using a
simple assay) than the original gene product.
C. the reporter gene is larger than the original gene and therefore more stable
than the original gene.
D. the reporter gene codes for a product that is safer than the original gene
product.
E. All of the above
____ Mobilizable plasmids require a self-transmissible “helper” plasmid because they
lack which of the following?
A.
B.
C.
D.
oriT
broad host range origin of replication
genes that encode the mating bridge
antibiotic resistance genes
____ A small portion of a 1 liter flask culture of an ampicillin sensitive strain of E. coli
(approximately 108 bacteria) is spread on an agar plate containing ampicillin. After a
24 hour incubation, 50 ampicillin resistant colonies are observed. When did these
ampicillin bacteria arise?
A. in the 1 liter flask, during incubation in the absence of ampicillin
B. on the agar plate, during incubation in the presence of ampicillin
C. E. coli cannot spontaneously become resistant to ampicillin
____ Why do linear DNA fragments only integrate into the chromosome but
plasmids can exist free in the cytoplasm?
A.
B.
C.
D.
Fragments
Fragments
Fragments
Fragments
lack
lack
lack
lack
a promoter.
an origin of replication.
a resistance gene.
a reporter gene.
____ Which of the following is not a mechanism for horizontal gene transfer in
nature?
A.
B.
C.
D.
conjugation
electroporation
transduction
transformation
____ Max Delbrueck and his colleagues designed an experiment to demonstrate
that mutations arise before an organism is exposed to a selective agent. This type
of test was called the ____.
A.
B.
C.
D.
E.
variability test.
fluctuation test.
fermentation test.
induction test.
Ames test
____ In the figure to the right, which
diagram best represents the arrangement
of components at time 0?
Short answer (variable points)
Why is the redox potential of the reaction center chlorophyll of the oxygenic
phototroph, Anabaena sphericus, greater than +1.0 V?
Why do anoxygenic phototrophs contain reaction center bacteriochlorophylls that
absorb light at wavelengths that are very different than the chlorophylls of the
cyanobacteria?
Complete the following table (2 points). What will happen to lac operon expression
in an E. coli cell containing the following mutation(s) Use a (+) if the lac operon will
be expressed and a (-) if the lac operon will not be expressed. (Assume there is no
glucose in the medium).
+ Lactose
lacIS
- Lactose
(super repressor)
lacIq (constitutive repressor)
lacOC (constitutive operator)
lacIs and lacOC
In the previous question, why was it important to state that there is no glucose in
the medium?
Why are polychlorinated biphenyls (PCBs) do difficult to degrade in the
environment?
Why do bacteria often secrete a wide assortment of extracellular enzymes?
Name 2 things have we learned from sequencing 16S rRNA genes?
Describe one advantage and one disadvantage for bacteria to organize certain
genes in operons.
Explain why Deinococcus radiodurans is resistant to such high levels of radiation.
When calculating evolutionary distances by sequence analysis you count then
number of differences in the nucleotide sequences of two different organisms and
multiply by a correction factor. Why is this correction factor necessary?
How does the tree of life, based upon 16S rRNA gene sequences support the theory
that some of the first life forms were able to thrive at the high temperatures of the
early earth?
What is the Ames test used for?
VERY briefly explain how the Ames test works. (in other words, not a description of
the procedure, just what is being measured)
Short essay (6 points each) Please answer 3 of the 4. 6 bonus points
possible for answering all 4.
Describe the basic steps in peptidoglycan synthesis and explain how penicillin
affects cell wall synthesis by actively growing cells.
Describe three mechanisms of transcriptional and three methods of translational
control of gene expression.
Describe the three major mechanisms for horizontal gene transfer. Include a brief
description of the mechanism(s) for DNA transfer for each.
Many of us are taught that respiration is the consumption of molecular oxygen and
photosynthesis is the generation of molecular oxygen. Now that you know how these
processes function in the microbial world, explain why this is not necessarily the case.
Perhaps it might be better to describe them as “complementary” process. Give some
examples of how respiration and photosynthesis complement each other.