Chapter 6. Microbial metabolism: Fueling Cell Growth (II)
Freely moving in the membrane where they can shuttle electrons between protein complexes. Grouped into large protein complexes that function as proton pumps.
In an electron transport chain, electron carriers are found in what two general locations?
lacks cytochrome c
Escherichia coli and Pseudomonas aeruginosa both have an electron transport chain that uses O2 as a terminal electron acceptor, yet E. coli is oxidase negative. Based on this information, it is logical to assume that E. coli ______.
true
With respect to the location of the electron transport chain, the inner membrane of mitochondria is analogous to the cytoplasmic membrane of bacterial cells.
By structurally related families that share common biosynthesis pathways
With respect to their synthesis, how are amino acids typically grouped?
Saccharomyces species (yeast) and Zymomonas species (bacteria)
What microorganisms use a fermentation pathway that results in CO2 and ethanol production?
NADPH and ATP
Which of the following combinations of molecules is produced during the light-dependent reactions of photosynthesis and used in the light-independent reactions?
Several different cytochromes exist. Cytochromes are proteins that contain heme, a molecule that holds an iron atom in its center.
Which of the following correctly describe cytochromes found in an electron transport chain?
The terminal electron acceptors used in anaerobic respiration have lower electron affinities than O2.
Why does anaerobic respiration yield less energy than aerobic respiration?
false
With respect to prokaryotic species such as E. coli, each individual cell will have an electron transport chain made up of the same components.
Gram-positive lactic acid bacteria
Lactic acid is a common fermentation product of which of the following types of cells?
Creating flavor and texture of yogurt and certain cheeses. Results in food spoilage. Production of pickles and cured sausages. Contributes to tooth decay.
Lactic acid production by fermenting microorganisms has many benefits for humans, but also can cause some problems. Which of the following are examples of these advantages and disadvantages?
exist as several types, including ubiquinone and menaquinone are lipid-soluble organic molecules that move freely in the membrane, transferring electrons between different protein complexes
A general group of electron carriers found in electron transport chains is quinones, that ______.
Clostridium
A genus that includes obligate anaerobes that can produce butyric acid and a number of other end products via fermentation is
precursor
After a deamination reaction removes the amino group from amino acids, the remaining carbon skeletons are converted into the appropriate metabolites for entry into central metabolic pathways.
ATP
All of the following are essential for an electron transport chain to function EXCEPT ______.
synthase
As part of cellular respiration, a membrane-bound enzyme called ATP uses energy from a proton-motive force to add a phosphate group to ADP.
It often involves the Calvin cycle. It is called carbon fixation. In photosynthetic organisms, the process is called the light-independent reactions.
Autotrophs use carbon dioxide (CO2) to synthesize organic compounds. Which of the following descriptions of this process are true?
Yes, Clostridium species are able to use fermentation.
Clostridium species are obligate anaerobes. Might they be able to grow using fermentation, or must they use anaerobic respiration?
reduced
Consider the representation of an electron transport chain. O2 is serving as the terminal electron acceptor. Is it being oxidized or reduced?
two
Cyanobacteria and photosynthetic eukaryotic cells have how many distinct types of photosystems?
glycolysis
Microorganisms that can grow on polysaccharides and disaccharides first break these down to glucose or precursor metabolites that can then enter into the pathway of to be oxidized.
20
Proteins are composed of various combinations of usually how many different amino acids?
Prokaryotes only
Some members of which of the following groups can use inorganic chemicals such as hydrogen sulfide and ammonia for energy?
glucose, glycolysis
Starch and cellulose are both polymers made up of the monosaccharide , which means that hydrolysis of the polymers releases subunits that can enter directly into the central metabolic pathway of to be oxidized.
four
The electron transport chain of mitochondria has ______ different protein complexes.
after; synthesize organic compounds from CO2
The light-independent reactions of photosynthesis occur _______ the light-dependent reactions, and function to _______.
oxidiative
The mechanism by which cellular respiration uses reducing power generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP is phosphorylation.
carbon fixation
The process by which chemolithoautotrophs and photoautotrophs incorporate CO2 into organic compounds is called
light dependent
The reactions that capture radiant energy and convert it into chemical energy in the form of ATP are called the - reactions.
quinones, cytochromes
The three main types of electron carriers in a typical electron transport chain are , , and flavoproteins.
Complex IV - Cytochrome c oxidase complex
There are four electron transport carriers in the ETC of eukaryotes. Which pair is correctly matched?
reaction
center pigments function as electron donors in the photosynthetic process, emitting high-energy electrons that are then passed to an electron transport chain.
They will grow aerobically, consume the O2 dissolved in the juice, and then switch to fermenting sugars to yield alcohol.
Although the actual procedure is much more involved, the basic metabolism of wine-making involves inoculating grape juice with a special strain of the yeast Saccharomyces cerevisiae. S. cerevisiae will preferentially perform aerobic respiration on sugars in the juice but can also ferment those sugars to yield CO2 and alcohol, an important component of wine. Assume you inoculate a completely full container of juice and then close the lid. What will the yeast do?
CO2
Considering the general equation that describes photosynthesis, the rate of the process would be most influenced by the availability of _______ in the atmosphere.
aerobic, anaerobic
E. coli will preferentially use respiration in the presence of O2, but when O2 is not available, it can switch to respiration if a suitable electron acceptor such as nitrate is present.
some accept only hydrogen atoms (proton-electron pairs), whereas others accept only electrons
Electron carriers of the electron transport chain are able to move protons across a membrane. They are able to do so because ______.
It detects the activity of cytochrome c oxidase, a component of the electron transport chain of some but not all bacteria.
How does the oxidase test help in bacterial identification?
energy source
Hydrogen sulfide is produced as a result of certain types of anaerobic respiration. Some chemolithotrophs can then use this as a/an ______.
38 ATP
If the theoretical maximum ATP yield in prokaryotes from oxidative phosphorylation is 34 ATP for a single glucose molecule, what is the total ATP gain when substrate-level phosphorylation is included?
serves as a source of vitamin K, providing much of the host's requirement via absorption in the intestinal tract
Menaquinone is a quinone used in the electron transport chain of some prokaryotes. It plays an important role for humans and other mammals because it ______.
They break these macromolecules down into appropriate precursor metabolites that are then introduced into central metabolism or used in biosynthesis.
Microorganisms can grow on a variety of organic compounds other than glucose, including polysaccharides, proteins, and lipids. How do they accomplish this?
They consume excess reducing power in order to regenerate NAD+ so that it can accept electrons to keep glycolysis going.
Other than generating some ATP via the substrate-level phosphorylation steps of glycolysis, what critical role do the additional steps of fermentation accomplish?
The electron transport chain generates a proton motive force. ATP synthase uses the energy of the proton motive force to drive the synthesis of ATP.
Oxidative phosphorylation, the mechanism by which cellular respiration uses the NADH and FADH2 generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP, involves what two steps?
water
Oxygenic photosynthesis produces O2 from the splitting of molecules.
anoxygenic
Photosynthesis in groups of bacteria called purple and green bacteria involves the use of H2S instead of water. This process is called photosynthesis.
Generate ATP via photophosphorylation; generate reducing power
Photosynthetic organisms use the light-dependent reactions to accomplish which two tasks?
amino acid
Proteins are hydrolyzed by proteases, enzymes that break the peptide bonds between subunits.
substrate-level phosphorylation during glycolysis
The ATP generated by fermentation comes from ______.
incorporates carbon dioxide into organic compounds
The Calvin cycle ______.
flavoproteins
The general group of electron carriers synthesized from the vitamin riboflavin is called
light-dependent reactions of photosynthesis
The generation of ATP via photophosphorylation and the generation of reducing power in the form of either NADPH or NADH are accomplished during the ______.
NADH + H+ are donating 2 electrons and 2 protons to pyruvate, an organic terminal electron acceptor, reducing it to lactate.
The lactic acid fermentation pathway is shown here. What statement best explains what is happening in the diagram?
They lack an electron transport chain. A suitable inorganic terminal electron acceptor is not available.
Which of the following are reasons an organism might use fermentation?
CO2 removal converts pyruvate to the terminal electron acceptor acetaldehyde, which receives 2 electrons and protons from NADH + H+, making ethanol.
This diagram depicts the production of ethanol from pyruvate via fermentation. What best explains the mechanism?
transport chain
This picture of a set of stairs best exemplifies the electron .
It must have the end product provided from an external source.
What happens to an organism if it lacks one or more enzymes in a given biosynthetic pathway?
bread making making biofuels wine and beer making
Ethanol can be produced during fermentation by removing CO2 from pyruvate to generate acetaldehyde, which then serves as the terminal electron acceptor, yielding ethanol. Humans have taken advantage of microorganisms capable of this process in a number of ways. Which of the following are examples of this?
cytochromes
Examples of electron carriers are proteins that contain heme, a molecule that holds an iron in its center. These are called
The precursor metabolites from glycerol enter glycolysis; the 2-carbon units from fatty acids are added to coenzyme A and enter the TCA cycle.
Fats are hydrolyzed by lipases. The glycerol component is then converted to a precursor metabolite, and the fatty acids are degraded using a series of reactions called β-oxidation that remove successive 2-carbon units. Where do these components enter the central metabolic pathways for further oxidation?
glycerol and fatty acids
Fats, the most common simple lipids, are broken down by lipases into their component ______.
riboflavin; electron transport chain
Flavoproteins are synthesized from the vitamin _______ and play a major role in the _______.
electron carriers; shuttle electrons between the complexes
In addition to four protein complexes, the mitochondrial electron transport chain has two freely-moving ______, ubiquinone and cytochrome c, that serve to ______.
fatty acids proteins monosaccharides polysaccharides disaccharides lipids
In addition to glucose, which of the following organic compounds can serve as energy sources for microbes?
photosystem II
In non-cyclic photophosphorylation, electrons from _______ are used to replenish the electrons lost from photosystem I. Multiple choice question. NADPH
electron
In oxidative phosphorylation, quinones, cytochromes, and flavoproteins are all carriers.
The process strips electrons from H2O, generating O2.
In photosynthesis by cyanobacteria and chloroplasts, why is O2 generated
The process strips electrons from H2O, generating O2.
In photosynthesis by cyanobacteria and chloroplasts, why is O2 generated?
They capture radiant energy and convert it to chemical energy in the form of ATP.
In photosynthesis, what do the light reactions, or light-dependent reactions, accomplish?
The energy yield of aerobic respiration is greater than anaerobic respiration.
In prokaryotes, how does the energy yield of aerobic respiration compare to anaerobic respiration?
cytoplasmic, inner
In prokaryotes, the electron transport chain is located in the membrane, whereas in eukaryotic cells it is in the membrane of mitochondria.
It uses the energy released from allowing protons to flow back into the cell to add a phosphate group to ADP.
In respiring bacteria, how does ATP synthase generate ATP?
highly diverse; remarkably similar
In terms of their metabolism, prokaryotes are _______ with respect to compounds they use for energy and _______ in their biosynthetic processes.
glucose and oxygen
In the case of plants, algae, and cyanobacteria, the two major products of photosynthesis are ______.
oxygen
In the representation of an electron transport chain (shown), the terminal electron acceptor is
false
The Calvin cycle is a two-step linear pathway that photosynthetic organisms use to fix carbon dioxide
Complex I accepts electrons from NADH Complex II accepts electrons from FADH2 Complex III accepts electrons from ubiquinone Complex IV accepts electrons from cytochrome c
The ETC of mitochondria consists of four different protein complexes. Match each with its appropriate function. Instructions
protons
The electron transport chain consists of large protein-complexes embedded in a membrane. These pass electrons from one to the next, while simultaneously pumping across the membrane,
NADH, FADH2
The electron transport chain is a cluster of membrane-embedded electron carriers that accept electrons from the coenzymes and and then pass these electrons along the chain.
water
The electrons lost from photosystem II are replaced by electrons derived from a molecule of
Function as electron donors, emitting high-energy electrons that are then passed to an electron transport chain
What is the role of reaction-center pigments?
