Download 221_ exam_1_2004

BioSc221/325
Exam 1
Name ______________________________
Multiple choice. (2 point each) Choose the one best answer to each of the following questions.
____ Fossilized stromatolites, which provide a geological record of early microorganisms, were formed from
A.
B.
C.
D.
layers of decayed marine animals that were degraded by microorganisms
layers of decayed marine plants that were degraded by microorganisms
microbial mats, layers of microbial communities
chemicals that formed during the early earth that came together to form the first microorganisms
____ In general, prokaryotic cells are __.
A.
B.
C.
D.
larger than eukaryotic cells
smaller than eukaryotic cells
about the same size a eukaryotic cells
not physiologically comparable to eukaryotic cells and therefore proaryotic and eukaryotic cell sizes should not be
compared.
____ The three domains of life are
prokaryotes, eukaryotes, eubacteria
protists, plants, animals
plants, animals, monera
bacteria, archaea, eukarya
____ Enzyme found in tears that cleaves the -1,4 linkage of the peptidoglycan layer.
A.
B.
C.
D.
lysozyme
murein
penicillin
vancomycin
____ Bacteriophage lambda has provided a wealth of information for biologists interested in how microorganisms make
“decisions” because lambda “decides” between
infecting Escherichia coli or Salmonella typhimurium
a lytic or lysogenic life cycle
lysing its host cell or budding from the host cell membrane
forming a plaque or a colony
_____ Antiviral drug therapy ideally should target viral activities that are unique to the virus. One of these targets is the
process or attachment. A fairly new anti-influenza drug targets _____ a protein on the surface of the influenza virus which is
associated with the attachment process.
A.
B.
C.
D.
influenza capsomer protein
pilin
neuraminidase
porin
____ An organism requiring many growth factors and only grows on a complex
medium is described as
A.
B.
C.
D.
finicky
selective
facultative
fastidious
____Archaea acquired their name because they were thought to be ancient in the fact that they resemble some of the earliest
microorganisms. That is because these organisms live in ___ conditions which resemble the conditions on early earth.
A.
B.
C.
D.
E.
anoxic
high temperature
high saline
All of the above
None of the above
____ A bacterial cell which has lost its peptidoglycan layer but remains intact is called a(n)
A.
B.
C.
D.
lysozome
protoplast
periplasm
osmoplast
____ Proteins that form channels in the outer membranes of gram-negative bacteria.
A.
B.
C.
D.
bactoprenols
lipoproteins
porins
transport proteins
____ Attachment is an essential step for pathogenic bacteria to infect their host. Many bacteria have long filamentous protein
structures that aid in this process. These structures are called
A.
B.
C.
D.
porins
pili
receptors
teichoic acids
____ AZT is an antiviral drug used to treat patients with HIV infections. Although this nucleotide analog can also be harmful
to the host cell machinery it is effective because _____, an enzyme that is unique to HIV, preferentially tries to use AZT over
the normal nucleotides.
A.
B.
C.
D.
reverse transcriptase
DNA polymerase
RNA polymerase
ligase
____ Molecules found in halophiles that protect them from the low water activity of their environment.
A.
B.
C.
D.
compatible solutes
halites
halogens
isotoners
____ Microscopes that are designed to enhance the contrast between cells and their surrounding medium are called
A.
B.
C.
D.
bright field
dark-field
phase contrast
epifluorescent
____ Methanogenic archaea are prokaryotic organisms that are found in anoxic conditions and only use molecules with one
carbon as their carbon source. Which of the following describes the conditions for an enrichment culture for methanogenic
archaea from the human colon?
A.
B.
C.
D.
Carbon dioxide, hydrogen, oxygen free
Carbon dioxide, oxygen rich
Glucose, oxygen free
Glucose, oxygen rich
____ Lipopolysaccharide (LPS) is associated with __ .
A.
B.
C.
D.
the outer membrane of Gram-positive bacteria.
the outer membrane of Gram-negative bacteria.
the cytoplasmic membrane of Gram-positive bacteria.
the cytoplasmic membrane of Gram-negative bacteria.
____ The objective lenses of modern light microscopes are described as compound lenses because they consist of several
lenses of different shapes (convex or concave) and different glass. The purpose of these compound lenses is to
A.
B.
C.
D.
correct spherical and chromatic aberrations
increase resolving power
extend the length of the lens to get closer to the sample
to match the optical properties of the microscope slide, coverslip and immersion oil
____ Form of oxygen that is toxic to living organisms
A.
B.
C.
D.
E.
hydrogen peroxide
singlet oxygen
superoxide
none of the above
all of the above
____ Electron microscopes are used to visual bacterial subcellular structures. The ability to resolve such small structures is
achieved through
the short wavelength of electrons
the ability to get the lenses of the electron microscope very close to the sample
that high intensity of the electron beam
all of the above
none of the above
____ When doing a colony count __.
A.
B.
C.
D.
It is assumed that each colony arose from only one organism.
Only viable cells are counted
The medium must be suitable for colonial growth
All of the above
____ The bacterial “cannibal” Bdevolovibrio bacteriovorans” moves toward its prey by responding to chemical signals.. This
type of movement is described as
A.
B.
C.
D.
random walk
brownian motion
chemiosmosis
chemotaxis
____ Enveloped viruses exit their host cell by a process called
A.
B.
C.
D.
lysis
lysogeny
extraction
budding
Matching. (1 point each) Match the definition in the left column with the appropriate term in the right column. Note, not all
terms will be used.
____ Molecule found in the cell wall of Gram-positive but not Gram-negative bacteria.
____ Associated child-bed fever with medical students not washing their hands after surgery.
____ The first to use an epidemiological approach to solving a disease outbreak (cholera).
____ Identified the causative agents of the deadly diseases anthrax and tuberculosis
____ Cocci arranged in "grape-like" clusters.
____ A culture technique in which conditions favor the growth of the desired type of organism.
____ A device for enumerating microorganisms by microscope instead of cultivation.
____ Bacteria that remain blue after completion of the Gram stain procedure.
____ Technique that makes it possible to separate large genome size DNA fragments on a gel.
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
L.
M.
N.
O.
P.
Q.
R.
Enrichment
Gram-negative
Gram-positive
Koch, Robert
Lipoteichoic acid
Murein
N-acetylmuramic acid
N-acetyltalosaminuronic acid
Pasteur, Louis
Peptidoglycan
Petroff-Hauser counter
Pseudopeptidoglycan
Pulsed-field Gel
Electrophoresis
Sarcina
Semmelweis, Ignaz
Snow, John
Staphylococci
Streptococci
Short answer. (1 point each)
Penicillin can kill bacteria because it interferes with ______________________.
A bacterium that has an optimal growth temperature of 37 oC but still grows at 4oC is described as ______________________.
A bacterium that has an optimal growth temperature of 30 oC would be described as a ___________________________.
An organism that requires a pH of 9.5 for optimal growth would be called a(n)___________________________.
Thiomargarita namibiensis is the largest known prokaryote (actually visible without a microscope). Briefly explain why large
prokaryotes are rare.
Give one reason why microbiologists have failed to cultivate many of the microbes in the environment.
Poliovirus is an enterovirus that primarily infects the cells of the gastrointestinal tract. In general terms, what is responsible for
this specificity?
The diagram below illustrates a series of dilutions of a culture of Escherichia coli. One tenth of a milliliter (0.1 mL) of each
dilution is plated on an agar medium that supports the growth of E. coli. The number in each circle represents the number of
colonies observed on each plate. Calculate the number of viable bacterial cells in one milliliter of the original sample.
Describe two features that distinguish prokaryotes from eukaryotes.
Myxococcus xanthus exhibits gliding motility. Name one other type of motility that bacteria can use.
Short Essay Questions. Please answer 3 of the following 4 short essay questions (5 points each - 5 bonus points possible for
answering all 4 questions)
Describe the structure of the outer membrane of a Gram-negative bacterium in as much detail as possible. Include a
description of any key components of the outer membrane. A labeled picture is OK.
Describe the steps in the Gram stain, including what is happening to the organisms being stained at each step and how the stain
differentiates Gram positive from Gram negative cells.
List four different methods for counting cells/measuring cell growth. Briefly describe each method and briefly explain the
advantages and disadvantages of each.
Briefly describe the 4 steps in the viral infection process.