13. metabolic Diversity of MO Flashcards
What are the light-harvesting structures of cyanobacteria and red algae called?
LH2
chlorosomes
phycobilisomes
thylakoids
phycobilisomes
During photosynthesis, what causes the special pair of bacteriochlorophyll a molecules to become a strong reductant?
the proton motive force
oxidizing the electron donor H2S
reduction by the quinone pool
absorption of light energy
absorption of light energy
Incorrect. Your answer should consider that when activated this special pair of bacteriochlorophyll a molecules initiates the photochemistry of photosynthesis.
How is oxygen generated during oxygenic photosynthesis?
Water is oxidized to produce O2 and electrons, which then reduce the oxidized P680 reaction center.
Electrons from the Z-scheme are transferred to water (the terminal electron acceptor) and this leads to oxygen production.
Cyclic photophosphorylation releases O2 from the CO2 as it is converted into organic material.
Electron flow through the Z-scheme generates ATP, which is used to break water into oxygen and protons.
Water is oxidized to produce O2 and electrons, which then reduce the oxidized P680 reaction center.
What is the chemical composition of the membranes of the polyhedral cell inclusions found in some Calvin cycle autotrophs?
ether-linked lipid monolayer
proteins
ester-linked lipids
ladderane lipids
:
proteins
Incorrect. You should consider that this is a thin membrane, which is different than the cytoplasmic membrane.
Which of the following choices best describes the path of electrons in chemolithotrophs that are growing in hydrogen gas?
H2 → quinones → cytochrome acceptors → O2
O2 → quinones → cytochrome acceptors → H2
H2 → O2 → quinones → cytochrome acceptors
H2 → cytochrome acceptors → quinones → O2
H2 → quinones → cytochrome acceptors → O2
What causes the production of the red colors in culture tubes of Acidithiobacillus ferrooxidans?
Figure 13.23b
Fe(OH)3 precipitates
carotenoid pigments
rusticyanin
bacteriochlorophyll
:
Fe(OH)3 precipitates
Which autotrophic pathway is utilized by organisms that oxidize ammonia?
hydroxyproprionate pathway
acetyl CoA pathway
Calvin cycle
reverse citric acid cycle
Correct Answer:
acetyl CoA pathway
Incorrect. Your answer should consider that the pathway these organisms utilize is thought to be one of the earliest autotrophic pathways in existence.
What process creates a proton motive force during oxalate fermentation in Oxalobacter formigenes?
the import of the dicarboxylic acid oxalate that is coupled to the export of the monocarboxylic acid formate
the hydrolysis of ATP by ATP synthase
a proton pump that is coupled to the decarboxylation of oxalate
a sodium pump that is coupled to the decarboxylation of oxalate coupled to the use of a Na+/H+ antiporter
Correct Answer:
the import of the dicarboxylic acid oxalate that is coupled to the export of the monocarboxylic acid formate
Incorrect. Your answer should consider that the proton motive force is composed of both a proton gradient and a charge gradient. These two components are interchangeable with each other.
What process is detrimental to soil productivity, yet beneficial for wastewater treatment?
assimilative sulfate reduction
nitrogen fixation
denitrification
carbon fixation
denitrification
Incorrect. Your answer should consider that this process is a type of anaerobic respiration.
How many electrons are required for the reduction of SO42- to H2S?
Two
Four
Six
Eight
orrect Answer:
Eight
Incorrect. Your answer should consider that a number of intermediate stages are required because this reduction involves multiple electrons.
In addition to substrate-level phosphorylation, how is ATP generated in acetogenesis?
through the establishment of a sodium motive force as acetyl-CoA is synthesized
through the establishment of a proton motive force as acetate is decarboxylated
through the generation of a proton-motive force as electrons are shuttled down an electron transport chain
through the formation of ATP by photophosphorylation
Answer:
through the establishment of a sodium motive force as acetyl-CoA is synthesized
Incorrect. Your answer should consider that a second way of making ATP has similarities to the method involved in succinate fermentation.
n the modified glycolytic pathway found in Pyrococcus furiosus, what is the immediate electron acceptor for the oxidation of glyceraldehyde-3-phosphate?
H+
Ferredoxin
NAD+
NADP+
Ferredoxin
Incorrect. Your answer should consider that glyceraldehyde-3-phosphate is oxidized to directly form 3-phosphoglycerate in Pyrococcus
What type of enzyme is utilized in the first step of the aerobic oxidation of an aliphatic hydrocarbon?
monooxygenase
dioxygenase
dhydrogenase
acetyl-CoA synthetase
Answer:
monooxygenase
Incorrect. Your answer should consider that a single oxygen atom is incorporated into the hydrocarbon.
Which chemical is produced by light energy as a direct result of photosynthesis?
ATP
H2
CO2
chlorophyll
ATP
Which organisms grow at the lowest light intensities of all known phototrophs?
algae
green plants
purple sulfur bacteria
green sulfur bacteria
Correct Answer:
green sulfur bacteria
Incorrect. The use of chlorosomes by these organisms gives them the capacity of phototrophic growth at extremely low light intensities.
What is the primary role of carotenoid pigments in photosynthesis?
photoprotection
structural
light harvesting
reaction center chemistry
photoprotection
4 Photosynthesis in purple phototrophic bacteria begins when energy is transferred to what structure?
two molecules of quinone
the antenna pigments
the special pair
the thylakoid membranes
the special pair
Which of the following pairs is matched correctly?
photosystem II - P680
photosystem I - P680
photosystem I - P720
photosystem II - P700
photosystem II - P680
Incorrect. Photosystems contain the special pair of chlorophyll molecules for photosynthesis, which absorb light at a specific wavelength.
Which of the following chemicals is NOT an electron donor for chemolithotrophy?
Fe2+
H2O
NH4+
HS-
H2O
What is the name of the enzyme that oxidizes hydrogen for chemolithotrophic growth?
hydrogen reductase
ATPase
cytochrome oxidase
hydrogenase
End of Question 7
hydrogenase
Incorrect. The enzymes that oxidize hydrogen are integral membrane proteins.
Which of the following sulfur compounds is NOT commonly used as an electron donor in chemolithotrophic metabolism?
S2O32-
SO
H2SO4
H2S
H2SO4
Incorrect. There are many reduced sulfur compounds that are used as electron donors. It is important to know the difference between a reduced sulfur compound and one that is oxidized.
Which of the following is a periplasmic protein that is involved in the electron flow in iron oxidation?
ATPase
quinones
rusticyanin
ferredoxin
rusticyanin
Incorrect. The correct answer transfers electrons between cytochrome c in the outer membrane and cytochrome aa3 in the cytoplasmic membrane.
Who discovered the process of nitrification?
Calvin
Beijerinck
Cohn
Winogradsky
r:
Winogradsky
Incorrect. This Russian microbiologist made this discovery at the end of the nineteenth century.
What was the first anoxic ammonia-oxidizing organism described?
Nitrospira
Nitrosomonas
Nitrobacter
Brocadia
Brocadia
Incorrect. This anaerobe is a member of the Planctomyces phylum.
Which catabolic pathway do mixed-acid fermenters, such as Escherichia coli, use in the fermentation of glucose?
glycolysis
β-oxidation
Enter-Doudoroff
pentose phosphate
glycolysis
Which of the following compounds is NOT a product of amino acid fermentation by Clostridium?
acetoin
CO2
NH3
fatty acids
acetoin
Which of the following is NOT a characteristic of syntrophy?
One or more products are continually removed from the reaction.
It occurs in oxic environments.
Syntrophic organisms are highly specialized for exploiting energetically marginal reactions.
Energy conservation may involve substrate-level phosphorylation and/or oxidative phosphorylation.
Correct Answer:
It occurs in oxic environments.
Incorrect. Syntrophy involves metabolic cooperation between two different microbes.
What is the first intermediate in the aerobic oxidation pathway of methane?
formate
formaldehyde
methanol
carbon dioxide
End of Question 15
methanol
