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Microbiology Exam 1 Practice Review
Terms in this set (37)
1. Desulfomonile is a bacterium that is capable of bioremediation of chlorbenzoate (C7H4O2Cl-) to benzoate (C7H5O2-) through a reductive dechlorination process. Consider the following redox couples for this organism: chlorbenzoate-/benzoate- (Cl-) (E0'= +0.297 V) and 2H+/H2 (E0'= -0.410V). Which reaction represents this redox reaction in the standard format of donor + acceptor products.
H2 + Chlorbenzoate - > 2H+ + Benzoate-
2. If hydrogen is the electron donor in a redox reaction, which electron acceptor has the greatest potential to produce the most energy? (see last page for the redox tower)
3. Which is a better electron acceptor (makes the most potential energy) than FAD+? (see last page for redox tower)
4. Does an enzyme change the free energy of a reaction it catalyzes?
5. Which of the following compounds would you expect a chemolithotroph to use for energy?
6. A leaf floating down a stream is colonized by many different types of microorganisms we refer to the organisms on this leaf as a ____________________________.
7. The earth was anoxic until about 2 billion years ago until the evolution of the _____________.
8. How are microbial cells (prokaryotes, protozoa, algae, etc.) fundamentally different then cells of higher organisms such as plants and animals?
Microbial cells are unicellular and higher organisms are multicellular
9. True or False. Biotechnology is an area of basic microbiology and it not considered applied microbiology.
10. Who was the first to discover bacterial endospores?
11. Who coined the term Chemolithotrophy?
12. True or False. A virus actually exhibits the properties of life after it has entered a host cell.
13. Which statement is MOST true about an aerobic chemoorganotroph?
It uses oxygen as a terminal electron acceptor and an organic compound for energy.
14. What is unusual about Halobacteria?
They have a pigment which helps in ATP production and they like a high salt concentration.
15. When Deinococcus was first isolated it was isolated from an unusual location. Based on what you know about this bug, which location makes the most sense?
A nuclear reactor
16. John took some lichen to the lab and decided to try to separate the two symbionts within lichen. He isolated the cyanobacteria just fine on some media, but couldn't get the fungus to grow on the media. What is the fungus missing?
An anchor or stabilizing structure on which to grow.
17. Peptidoglycan is pretty strong. The NAM-NAG backbone provide strength in the horizontal direction while the _____________ provides the strength in the vertical direction.
Techoic acids;Peptide side chains and cross bridges.
18. Sue wanted to characterize her collection of Gram Positive bacteria by their cell wall so she could note the diversity in the population she collected. "Wow, there are so many different cell wall chemicals to compare in the different bacteria to distinguish them from one another and I don't know which one to choose." What would you recommend to her?
The peptide cross-links and interbridges
19. Thiomargarita nambiensis is a cocccus shaped cell with a diameter of 1mm and S. aureus is a coccus shaped cell with a diameter of 2 µm. S. aureus divides every 20 minutes and T. nambiensis divides every 120 minutes. Why would S. aureus grow so much faster? (pick the most logical explanation).
It has a larger surface area per unit volume ratio.
20. Which transport system typically has the highest affinity for the substrates?
ATP Binding Cassette.
21. Which transport system phosphorylates the substrate as it enters the cell?
22. Which of the following is true about pili in a bacteria?
Pili are used to exchange genetic information.
23. What does a bacterial cell use to move vertically in a water column?
24. Which of the following is true about gliding motility?
Cells must be attached to a surface for gliding motility.
Calculate the change in reduction potential (ΔEo') AND the potential change in free energy (G0') for a redox reaction that uses Glucose as the electron donor which is oxidized to CO2 and oxygen as the electron acceptor which is reduced to water. ( 5 points) (see last page for redox tower and for the formula)
26. Provide one accurate reason why some microbiologists are suggesting that we should no longer use the term Prokaryote to describe the Archaea and the Bacteria.
Because the term means "before" nucleus. It isn't necessarily the case that many bacteria and archaea evolved prior to nucleated organisms and taxonomically we do not and should not name organisms based on what they do not have. Instead they should be named based on a common property they do have.
27. Consider the cell walls of Archaea and Gram Positive Bacteria and describe at least two differences in the cell wall of these two groups of organisms.
Archaea do not have a NAM and NAG Backbone that is linked via a beta 1,4 glycosidic bond like gram positive bacteria do. Archaea have a NAG and NATU backbone that is linked via a beta 1,3 glycosidic bond.
28. Plasma membrane
a. Do cells exists that lack a plasma membrane (yes or no)
b. Describe the purpose(s) of the prokaryotic plasma membrane.
b. i. Energy conservation (a place to create the proton motive force or gradient that is used to do work and make ATP).
ii. Semipermeable layer that selectively allows substrates to enter and exit the cell.
iii. Protein anchor which allows a location for transport proteins and chemoreceptors to exist so they can perform their functions effectively
c. How do the plasma membrane structures in Bacteria differ from the plasma membrane structures in archaea (use the correct chemical terminology in your answer—or abbreviations).
i. Bacteria have a phospholipid bilayer made up of phospholipids with a glycerol ester attached to a fatty acid chain.
ii. Archaea have more variety in their membranes. Some have lipid bilayers made up of glycerol diether attached to phytanyl chains. Some have lipid monolayers made up of diglycerol tetraethers attached to biphytanyl chains. Some have lipid monolayers made up of crenarchaol.
29. A microbiologist came up with 4 postulates to describe infectious disease agents.
a. Who was that microbiologist?
b. State the four postulates in order.
i. The causative agent has to be present in all diseased organisms and absent in healthy organisms
ii. The causative agent has to be isolated from the diseased organism and grown in pure culture.
iii. The pure culture that is isolated must be inoculated in a healthy organism and that healthy organism must obtain the same disease.
iv. The same causative agent must be then reisolated from the inoculated organism that has the disease
c. Give only one reason why it is difficult to use the postulates (as stated) today with certain pathogens.
Well, in the case of HIV, which only infects humans, it would not be ethical to inoculate a healthy human with the causative agent!
30. When the tree of Life was constructed by Carl Woese using the 16SrRNA analysis what two observations (provide detail here) led to Lynn Margulis endosymbiotic theory?
The fact that rDNA from chloroplasts are phylogenetically related to cyanobacteria suggesting that chloroplasts were once cyanobacterial symbionts. The fact that rDNA from mitochondria are phylogenetically related to proteobacteria suggesting that mitochondria were once proteobacteria symbionts
What is a barophile and where would you typically find one (try to be as specific as possible)?
Pressure-loving bacteria. They live in environments that have very high pressure, which usually means that the environment is also very hot. Barophiles exist in Deep Sea Vents (very hot and high pressure).
32. When a person breathes in endospores of Bacillus anthracis the spores germinate and cause a disease.
a. Give two reasons why the spores germinate.
----Increase in temperature and ----water/nutrient availability.
b. Name the disease and be specific.
c. Cindy had this disease and told her doctor that she was doomed since antibiotics can destroy an actual endospore. Explain what you would tell Cindy to fix this misconception.
-----The endospores no longer exist once they have germinated in her lungs. The vegetative cells that emerge are very sensitive to the antibiotics used so they should kill them.
Circle the following statements (there may be more than one) that are correct about flagella in prokaryotes
-----Proton motive force is used directly to power the motion of the bacterial flagella (versus burning of ATP).
----As the concentration of the attractant decreases the motor switch changes the rotation of the flagella and cell tumbles more than it runs.
Tell me what you know about Poly-β-hydroxybutyric acid .
Cells make this compound to store excess carbon. It is a polymer. It is used to make plastic bottles that are biodegradable.
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