| Question |
Explanation |
| 1. E |
Lipopolysaccharide is found in the outer
membrane, not the inner (cytoplasmic membrane). |
| 2. A |
Definition. |
| 3. B |
Peptidoglycan is the rigid material that shapes
the wall. |
| 4. B, G, H |
Analyze this carefully. (1) What is the C-source?
The question tells you that these bacteria "assimilate organic compounds
as C-sources" = heterotroph. (2) What is the E-source? "Hydrogen
gas" = chemolithotroph. (3) What is the catabolic style? Since it's
an anaerobe, you know it's not O2. Does it ferment?
Nothing in the question indicates that. Does it respire anaerobically? Yes,
it "uses CO2 as a terminal electron acceptor" = respires
anaerobically. Just because it uses CO2 does not
make it an autotroph, unless CO2 is the C-source, not
the case here. |
| 5. A, D, G |
Again, analyze. (1) What is the C-source? The
question tells you that these bacteria make all "cellular susbtrate from
carbon dioxide" = autotroph. (2) What is the E-source? It "oxidizes
nitrite" = chemolithotroph. (3) What is the catabolic style? It's
a strict aerobe, which means it must be respiring aerobically. |
| 6. E |
Generation time = division time (1 to 2 cells,
2 to 4 cells, etc.) |
| 7. E |
If one bacterial cell grew for 24 hours exponentially,
it would cover the earth 4 feet deep in bacteria. (Actually, since this
is Strep. faecalis, it would be 4 feet deep in s–t). No way that overnight
culture is still growing-- if you thought it was then you haven't paid much
attention in lab! Then to make it even clearer that growth is not an option,
you resuspend the cells in distilled water — nothing to eat = no growth.
Penicillin only affects growing cells. If you still think penicillin
will work, I've got some lovely real estate linking Brooklyn with Manhattan
that I'd like to sell …. |
| 8. D |
Pasteurization involves brief heating
sufficient to kill pathogens, but not all bacteria. The other techniques
can all be used to sterilize appropriate materials. |
| 9. A |
Protons are moving from out to in, and the carrier
simultaneously brings in amino acids. Both substances move inward together
= symport. |
| 10. A |
Viable counts are accurate over the entire range
of bacterial concentration, from a single cell to billions/ml. By contrast,
none of the other techniques (B-E) detect bacteria at concentrations below
107 cells/ml. |
| 11. C |
Definition |
| 12. A |
Lag phase occurs because bacteria must adapt
to a new environment. If you take growing cells in the middle of exponential
phase and put them into a new batch of the same medium, there is no new
environment, they're already fully adapted, so you wouldn't expect (nor
do you see) a lag phase. |
| 13. D |
Even if you don't remember the names of any
of the chemicals except pyruvate as an ending material, the diagram shows
an oxidation (NADH) followed by production of two ATP molecules — the
"harvest" phase of glycolysis, aka Embden Meyerhof pathway. |
| 14. A |
When cells detect an attractant, they lengthen
runs and tumble less frequently. This pattern persists as long as there
is any gradient of attractant. |
| 15. D |
Autolysins = "self-breaking" enzymes. Lysozyme
is an antibacterial enzyme produced by animals, not a bacterial enzyme. |
| 16. F |
Anabolic reactions, not catabolic, are biosynthetic
reactions. |
| 17. T |
Yes, since oxygen has the lowest redox potential,
more energy can be generated during electron transfer than with other acceptors. |
| 18. T |
This is one of the most fundamental differences
between prokaryotes and eukaryotes. |
| 19. T |
RP is directly proportional to wavelength; smaller
is better |
| 20. T |
What else are you going to call it? "Fungal
mycelium" is the usual way to mention the collective body of a mold,
made up mainly of hyphae. |
| 21. F |
30S and 50S subunits assemble to form 70S ribosomes;
40S + 60S = 80S |
| 22. F |
Bacterial proteins contain only L-amino acids,
like all other organisms. The only place you find D-amino acids are in short
peptides attached to glycan chains = peptidoglycan. |
| 23. F |
Many reactions with positive Delta Go'
values happen spontaneously under conditions that deviate significantly
from "standard" conditions. |
| 24. T |
ATP synthase is the only way to make ATP from
respiratory chains. |
| 25. F |
Mycoplasmas don't have walls, so penicillin
is useless. |
| 26. DABCE |
Cytoplasmic membrane is clearly innermost. Next
comes periplasm, next comes the outer membrane. LPS is anchored to the outer
membrane by lipid A (dissolved in a lipid bilayer); sticking out from lipid
A are polysaccharide chains including O. The capsule is the most peripheral
of all. |
| 27. |
SO4=, NO3-, and NO2- |
| 28. |
Ethanol and lactic acid are the reduced
products. CO2 is also a product, though not reduced
(it is split off before the NADH step) |
| 29. |
Capsules, slime layers, fimbriae, pili —
any of these |
| 30. |
"Osmotolerant acidophile"
is the best phraseology. |
| 31. 200 hours |
Substitute Nf = 109,
No = 103. Then calculate n = (9-3)/.3
= 6/.3 = 60/3 = 20 generations. Multiply by 10 hours/gen x 20 gen = 200
hours. |
| 32. |
PBHB forms intracellular energy storage
inclusion bodies in bacteria; Teichoic acid occurs in the peptidoglycan
layer of gram+ cells. |
| 33. |
Active transport requires energy and
concentrates solutes "uphill" against concentration gradients; facilitated
diffusion also uses protein carriers, but does not require energy and
can only allow solutes to flow "downhill" along a concentration gradient. |
| 34. |
Streps have enzymes such as catalase
and superoxide dismutase to get rid
of toxic oxygen byproducts; Clostridia don't. |
| 35. |
(1) Mitochondria and chloroplasts have 70S ribosomes,
not 80S.
(2) Mitochondria and chloroplasts divide by binary fission
(3) Mitochondria and chloroplasts have single circular DNA molecules like
bacteria |
| 36. |
NAD+; functions as a temporary
electron carrier (or redox carrier) |
| 37. |
Time = roughly 1880-early 1900s. Discovery =
identification of specific microbes as causes of specific diseases. |
| 38. |
Siderophore
= molecule secreted by cells to bind iron and make it available |
| 39. |
Auxotroph
= cell that lacks some biosynthetic ability, won't grow unless this nutrient
is supplied |
| 40. |
Strong oxidizing agents; strip electrons indiscriminately
from many organic molecules, disrupting cell function in many ways. |
