Bio Ch 6: Microbial Metabolism: Fueling Cell Growth
Metabolic pathways can be linear, _____ or _____
branched cyclical
In prokaryotes, the electron transport chain is located in the _____ membrane, whereas in eukaryotic cells it is in the _____ membrane of mitochondria.
cytoplasmic inner
The function of NAD+/NADH, NADP+/NADPH, and FAD/FADH2 in a cell is to carry _____
electrons / hydrogen
Consider how cells obtain energy to make ATP. The chemical that serves as the electron donor is the _____ source, and the one that ultimately accepts those electrons is the _____ electron acceptor
energy terminal
Hydrogen sulfide is produced as a result of certain types of anaerobic respiration. Some chemolithotrophs can then use this as a/an ______. energy source precursor metabolite terminal electron acceptor
energy source
All of the following accurately describe enzymes EXCEPT ______. enzymes are very specific, usually acting on only one or a few substrates enzymes are biological catalysts enzymes are not used up in the process of catalyzing reactions enzymes provide energy to help reactions proceed more rapidly the name of an enzyme typically reflects its function and ends in -ase
enzymes provide energy to help reactions proceed more rapidly
Use the following four words to correctly complete the sentence: endergonic, exergonic, anabolism, catabolism."Cells constantly produce ATP during _____ reactions of _____ and then use it to power _____ reactions of _____"
exergonic catabolism endergonic anabolism
What are the two main forms of energy? kinetic latent potential dynamic
kinetic potential
The enzymes of the tricarboxylic acid cycle are found in the _____ matrix in eukaryotes and in the _____ in prokaryotes.
mitochondrial / mitochondrion cytoplasm / cytosol
The reactions that capture radiant energy and convert it into chemical energy in the form of ATP are called the _____-______ reactions
light dependent
The series of sequential chemical reactions in a cell that converts a starting compound to an end product is called a _____ pathway
metabolic
TCA cycle completes the _______ of glucose reduction oxidation synthesis hydrolysis
oxidation
Proteins are hydrolyzed by proteases, enzymes that break the _____ bonds between amino acid subunits.
peptide / covalent
In addition to glucose, which of the following organic compounds can serve as energy sources for microbes? polysaccharides monosaccharides lipids disaccharides fatty acids proteins phosphate
polysaccharides monosaccharides lipids disaccharides fatty acids proteins
Energy is the ability to do work and can exist as _____ energy (stored energy) and _____ energy (energy of motion).
potential kinetic
In addition to yielding energy, catabolic pathways generate carbon intermediates that can be used in anabolic pathways for the biosynthesis of macromolecules. These carbon skeletons are called _____ _____
precursor metabolites
During cellular _____ , electrons extracted from glucose via the central metabolic pathways are transferred to the electron transport chain, where they are used to generate a proton motive force that can be harvested to make ATP via oxidative phosphorylation.
respiration
The central metabolic pathways together produce ______. glucose and oxygen water and carbon dioxide carbon dioxide and oxygen glucose and carbon dioxide
water and carbon dioxide
Proteins are composed of various combinations of usually how many different amino acids? 38 64 6 20
20
The Calvin cycle involves an enzyme commonly called rubisco. What is the product of the reaction it catalyzes? ribose-5-phosphate 3-phosphoglycerate fructose-6-phosphate dihydroxyacetonephosphate
3-phosphoglycerate
With respect to their synthesis, how are amino acids typically grouped? Alphabetically By their size and molecular weight By how many carbon atoms they contain By structurally related families that share common biosynthesis pathways
By structurally related families that share common biosynthesis pathways
The TCA cycle incorporates an acetyl group from the transition step and releases two different precursor metabolites, two molecules of _____ , and two molecules of _____ . (Not counting reducing power)
Co2 ATP
The three central metabolic pathways break down glucose, but also generate precursor metabolites and reducing power that can be diverted for use in anabolic pathways. To reflect this dual role, these pathways are sometimes called _____ pathways
amphibolic
The biochemical reactions in metabolism where the simple molecules combine to generate macromolecules is known as _______. metabolism anabolism amensalism catabolism
anabolism
Purple bacteria and green bacteria have only a single photosystem and cannot use water as an electron donor, with production of O2 as a byproduct. This makes them _____ photosynthetic bacteria.
anoxygenic
The statement "the substrate fits into the active site of an enzyme like a hand into a glove" refers to what important property of enzymes? The enzyme can work on many different substrates The enzyme completely surrounds the substrate The enzyme is much larger than the substrate Enzyme specificity Enzyme stability
Enzyme specificity
Which of the following are important electron carriers for a cell? FAD/FADH2 NADP+/NADPH NAD+/NADH ADP/ATP
FAD/FADH2 NADP+/NADPH NAD+/NADH
In the process called _____ , cells break down glucose via glycolysis and then use pyruvate or a derivative as a terminal electron acceptor.
fermentation
Atoms that are more electronegative than others ______. have a higher affinity for electrons have a higher ability to donate electrons have the capacity to create more electrons
have a higher affinity for electrons
The Calvin cycle ______. captures radiant energy, thereby allowing photosynthesis incorporates carbon dioxide into organic compounds is used by chemoorganoheterotrophs
incorporates carbon dioxide into organic compounds
Which of the following combinations of molecules is produced during the light-dependent reactions of photosynthesis and used in the light-independent reactions? CO2, NADPH, and ATP O2, NADPH, and glucose O2, NADPH, and ATP NADH and ATP NADPH and ATP
NADPH and ATP
In aerobic respiration, _____ serves as the terminal electron acceptor.
O2
_____ organisms harvest the energy of sunlight, using it to power the synthesis of organic compounds from CO2, whereas _____ obtain energy by degrading organic compounds made by others.
Photosynthetic chemoorganotrophs
Consider the ATP-generating processes of prokaryotic chemoorganoheterotrophs. Match the process with its correct terminal electron acceptor. Instructions Aerobic respiration - Anaerobic respiration fermentation -
Aerobic respiration - O2 Anaerobic respiration - molecule other than O2 such as nitrate, nitrite, or sulfate fermentation - organic molecule (pyruvate or a derivative)
For a single molecule of glucose, what is the theoretical maximum ATP gain from oxidative phosphorylation in prokaryotes growing aerobically? 4 ATP 34 ATP 18 ATP 6 ATP
34 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? 34 ATP 76 ATP 4 ATP 38 ATP 68 ATP
38 ATP
How many turns of the Calvin cycle does it take to generate one molecule of the 6-carbon sugar fructose? 4 6 1 3
6
When a cell processes glucose or other organic molecules through its central metabolic pathways, it does so to generate what three critical things? ATP, reducing power, ethanol ADP, NADH, glucose ADP, reducing power, lactic acid ATP, reducing power, precursor metabolites ATP, NAD+, pyruvate
ATP, reducing power, precursor metabolites
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.
NADH FADH2
What are the reduced forms of the electron carriers NAD+ and FAD? FADH NADH2 FADH2 FADPH NADPH NADH
NADH FADH2
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.
aerobic anaerobic
The light-independent reactions of photosynthesis occur _______ the light-dependent reactions, and function to _______. after; generate ATP and reducing power before; synthesize organic compounds from CO2 before; generate ATP and reducing power after; synthesize organic compounds from CO2 before; breakdown glucose to CO2 and H2O
after; synthesize organic compounds from CO2
The component of metabolism that involves the biosynthesis of macromolecules, using ATP for energy, is called _____
anabolism
When a molecule other than O2 serves as the terminal electron acceptor for the electron transport chain, the organism is utilizing _____ respiration
anaerobic
Photosynthesis in groups of bacteria called purple and green bacteria involves the use of H2S instead of water. This process is called _____ photosynthesis.
anoxygenic
An organism that uses hydrogen sulfide as an energy source is called a _______ and is most likely _______. chemolithotroph; eukaryotic chemolithotroph; prokaryotic chemoorganotroph; prokaryotic chemoorganotroph; eukaryotic
chemolithotroph; prokaryotic
Some prokaryotes can extract electrons from inorganic energy sources and pass them to an electron transport chain to generate a proton motive force to make ATP. These types of prokaryotes are called _____
chemolithotrophs
The pigment that gives plants their green color is called
chlorophyll
The primary pathway used by many organisms to convert glucose to pyruvate is
glycolysis / Embden-Meyerhoff
In terms of their metabolism, prokaryotes are _______ with respect to compounds they use for energy and _______ in their biosynthetic processes. remarkably similar; highly diverse highly diverse; highly diverse remarkably similar; remarkably similar highly diverse; remarkably similar
highly diverse; remarkably similar
An atom that has a lower affinity (attraction) for electrons than another is described as ______ than the other. more electronegative less electronegative
less electronegative
In the case of plants, algae, and cyanobacteria, the two major products of photosynthesis are ______. water and carbon dioxide glucose and carbon dioxide glucose and oxygen carbon dioxide and oxygen
glucose and oxygen
Lipid synthesis generally requires the components ______ and ______ acids
glycerol fatty
Fats, the most common simple lipids, are broken down by lipases into their component ______. glycerol and amino acids glycerol and fatty acids monosaccharides amino acids single carbons and hydrogens
glycerol and fatty acids
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
glycolysis
A dehydrogenation reaction is a(n) _______, while a hydrogenation reaction is a(n) _______. reduction; oxidation oxidation; reduction
oxidation; reduction
During cellular metabolism, three key metabolic pathways together gradually _______. These are collectively referred to as the central metabolic pathways. oxidize glucose to O2 reduce glucose to CO2 oxidize glucose to CO2 reduce glucose to O2
oxidize glucose to CO2
Each type of the major electron carriers is referred to by two different abbreviations (NAD+/NADH, NADP+/NADPH, and FAD/FADH2).The first of each pair refers to the _____ form and the second of each pair refers to the _____ form
oxidized reduced
In oxidation-reduction reactions, or redox reactions, the substance that loses electrons is _____ and the substance that gains those electrons is _____
oxidized reduced
The central metabolic pathway that breaks down glucose but whose primary role is the production of compounds used in biosynthesis, including reducing power in the form of NADPH as well as two precursor metabolites, is called the _____ _____ pathway
pentose phosphate
In photosynthesis, the protein complexes located within photosynthetic membranes that contain pigments and are responsible for capturing radiant energy are called _____
photosystems
After a deamination reaction removes the amino group from amino acids, the remaining carbon skeletons are converted into the appropriate a _____ metabolites for entry into central metabolic pathways.
precursor
When cells use glucose to make amino acids and other subunits for biosynthesis, certain intermediates of catabolism called _____ metabolites exit the "deconstruction line" of the breakdown process.
precursor
The ATP generated by fermentation comes from ______. the tricarboxylic acid (TCA) cycle oxidative phosphorylation driven by NADH the reducing power obtained from the oxidation of glucose substrate-level phosphorylation during glycolysis
substrate-level phosphorylation during glycolysis
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.
synthase
Energy is defined as ______. the result of work the use of ATP the ability to do work the result of metabolism
the ability to do work
True or false: The metabolism of photosynthetic organisms and chemoorganotrophs involves the creation of energy.
False Reason: Energy cannot be created or destroyed; instead, the cells convert energy from one for to another
Prokaryotic chemoorganoheterotrophs use various ATP-generating processes. Match the metabolic process with the information that correctly applies to it. aerobic respiration - anaerobic respiration - fermentation -
aerobic respiration - uses an electron transport chain; does not yield either the most of the least amount of ATP relative to the other two processes anaerobic respiration - uses an electron chain; yields more ATP than the other two processes fermentation - does not use an electron transport chain; yields the least ATP of the three processes
Although the pentose phosphate pathway is used by cells to break down glucose, it is particularly important because of its contribution to ______. control of phosphate levels biosynthesis cellular regulation the TCA cycle
biosynthesis
The removal of an electron from a biological molecule is typically followed by the loss of a _____ . The end result would be a removal of a hydrogen atom.
protons / H+
The pigments of photosynthetic organisms capture _____ energy
radiant
_____ -center pigments function as electron donors in the photosynthetic process, emitting high-energy electrons that are then passed to an electron transport chain.
reaction
cellular respiration uses the _____ power of NADH and FADH2 generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP.
reducing
Consider the maximum theoretical ATP yield from oxidative phosphorylation of a single molecule of glucose in prokaryotes. Match the relative contributions of the central metabolic pathways and final yield with their approximate contribution in terms of ATP. Include the following pair, already given: 6 ATP from the transition step. 6 ATP - 22 ATP - 34 ATP - total maximum yield TCA cycle glycolysis
6 ATP - glycolysis 22 ATP - TCA cycle 34 ATP - total maximum yield
In terms of reducing power, what are the products of the TCA cycle? 6 NADH and 2 FADH2 4 NADH and 4 FADH2 4 NADPH and 4 FADH2 6 NADPH and 2 FADH2
6 NADH and 2 FADH2
Cellular respiration involves the mechanism of oxidative phosphorylation, which uses the energy of a proton motive force to produce ______. ATP NADH O2 glucose pyruvate
ATP
The main energy currency of cells is the molecule called _____
ATP
Some members of which of the following groups can use inorganic chemicals such as hydrogen sulfide and ammonia for energy? Eukaryotes only Prokaryotes only Eukaryotes and prokaryotes
Prokaryotes only
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? Commonly used in wine making. Contributes to tooth decay. Giving flavor to and making holes in Swiss cheese. Creating flavor and texture of yogurt and certain cheeses. Results in food spoilage. Production of pickles and cured sausages.
Results in food spoilage. Creating flavor and texture of yogurt and certain cheeses. Contributes to tooth decay. Production of pickles and cured sausages.
Which of the three central metabolic pathways generates the most reducing power? Glycolysis TCA cycle pentose phosphate pathway
TCA cycle
The central metabolic pathway that splits glucose and gradually oxidizes it to form two molecules of pyruvate is _____
glycolysis
The three central metabolic pathways that gradually oxidize glucose to CO2 are _____ the _____ _____ pathway, and the _____ cycle
glycolysis pentose phosphate (TCA) Tricarboxylic acid
The mechanism by which cellular respiration uses reducing power generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP is _____ phosphorylation.
oxidative
Cells use three key metabolic pathways referred to as the central metabolic pathways. These collectively ______. oxidize glucose to CO2 oxidize glucose to O2 reduce glucose to CO2 reduce glucose to O2
oxidize glucose to CO2
The generation of ATP via photophosphorylation and the generation of reducing power in the form of either NADPH or NADH are accomplished during the ______. light-dependent reactions of photosynthesis light-independent reactions of photosynthesis aerobic respiration tricarboxylic acid cycle anaerobic respiration
light-dependent reactions of photosynthesis
The metabolic pathway that oxidizes a 2-carbon acetyl group to release two molecules of CO2 and generates the most reducing power of all the central metabolic pathways is called the _____ acid cycle
tricarboxylic
Anoxygenic photosynthetic bacteria like the purple bacteria and green bacteria may use any of the following as electron donors for reducing power EXCEPT ______. hydrogen gas (H2) water organic compounds hydrogen sulfide (H2S)
water
Place the following steps in the correct order to show how the spatial arrangement of electron carriers in a bacterial electron transport chain helps explain how protons are shuttled from one side of the membrane to the other. An electron carrier (e.g., NADH + H+) donates electrons to a hydrogen carrier, which also picks up protons. The hydrogen carrier passes electrons to a carrier that only accepts electrons. A proton motive force is set up as protons are moved from the inside of the cell to the outside Because the electron carrier only accepts electrons, the protons are released to the outside of the cell.
1. An electron carrier (e.g., NADH + H+) donates electrons to a hydrogen carrier, which also picks up protons. 2. The hydrogen carrier passes electrons to a carrier that only accepts electrons. 3. Because the electron carrier only accepts electrons, the protons are released to the outside of the cell. 4. A proton motive force is set up as protons are moved from the inside of the cell to the outside
In photosynthesis, what do the light reactions, or light-dependent reactions, accomplish? They use sunlight to convert CO2 into sugars by carbon fixation. They are the reactions of the Calvin cycle, which fix CO2. They capture radiant energy and convert it to chemical energy in the form of ATP. They use ATP to synthesize organic compounds.
They capture radiant energy and convert it to chemical energy in the form of ATP.
Certain intermediates of catabolic pathways, called precursor metabolites, are important because ______. they are required before the breakdown of glucose can occur. they are required for the function of certain enzymes they serve as carbon skeletons from which subunits of macromolecules can be made
they serve as carbon skeletons from which subunits of macromolecules can be made
Which of the following are reasons an organism might use fermentation? A suitable inorganic terminal electron acceptor is not available. They lack the ability to perform glycolysis. The energy yield is greater from fermentation than from respiration. They lack an electron transport chain.
A suitable inorganic terminal electron acceptor is not available. They lack an electron transport chain.
Photosynthetic organisms use the light-dependent reactions to accomplish which two tasks? Fix CO2; generate O2 Generate ATP via oxidative phosphorylation; generate reducing power Generate ATP via substrate-level phosphorylation; generate O2 Fix CO2; generate glucose Generate ATP via photophosphorylation; generate reducing power
Generate ATP via photophosphorylation; generate reducing power
Electron carriers of the electron transport chain are able to move protons across a membrane. They are able to do so because ______. some accept only hydrogen atoms (proton-electron pairs), whereas others accept only electrons they supply ATP, which is used in a phosphorylation reaction to move protons their protein structure includes a mobile component that physically ratchets to pump the protons across the membranes
some accept only hydrogen atoms (proton-electron pairs), whereas others accept only electrons
The step that links glycolysis to the TCA cycle is called the _____ step
transition
Oxygenic photosynthesis produces O2 from the splitting of _____ molecules
water
What is the role of reaction-center pigments? Serve as electron acceptors, thus facilitating the reduction of NADP+ to NADPH Act as a funnel, capturing light energy and then transferring it to the reaction-center Function as electron donors, emitting high-energy electrons that are then passed to an electron transport chain
Function as electron donors, emitting high-energy electrons that are then passed to an electron transport chain
Which of the following accurately describe fermentation? Glucose is broken down via glycolysis. All cells are able to ferment certain substances. Fermentation does not involve the tricarboxylic acid (TCA) cycle. It generates more ATP than either glycolysis or respiration. NAD+ is regenerated from NADH by the transfer of electrons to pyruvate or a derivative.
Glucose is broken down via glycolysis. Fermentation does not involve the tricarboxylic acid (TCA) cycle. NAD+ is regenerated from NADH by the transfer of electrons to pyruvate or a derivative.
Lactic acid is a common fermentation product of which of the following types of cells? Propionibacterium species Clostridium species Saccharomyces species Gram-positive lactic acid bacteria
Gram-positive lactic acid bacteria
What happens to an organism if it lacks one or more enzymes in a given biosynthetic pathway? It must have the end product provided from an external source. It will have to generate a mutation in its genome to allow it to produce the correct needed enzyme. It will need to create a new pathway in order to synthesize the compound. Natural selection will act against it, and it will be outcompeted and replaced by others that can synthesize the end product.
It must have the end product provided from an external source.
In respiring bacteria, how does ATP synthase generate ATP? It uses reducing power generated by the central metabolic pathways to add a phosphate group to ADP. It uses high energy phosphate bonds to transfer a phosphate group to ADP. It takes energy from NADH and FADH2 and uses it to add a phosphate group to ADP. It uses the energy released from allowing protons to flow back into the cell to add a phosphate group to ADP.
It uses the energy released from allowing protons to flow back into the cell to add a phosphate group to ADP.
In contrast to an exergonic reaction, which of the following accurately describe an endergonic reaction? The products have more free energy than the starting compounds. The starting compounds have more free energy than the products. The reaction consumes energy. The reaction releases energy as it proceeds.
The products have more free energy than the starting compounds. The reaction consumes energy.
Glucose catabolism encompasses two key processes: (1) oxidizing glucose molecules to generate ATP, reducing power, and precursor metabolites; and (2) transferring the electrons carried by NADH and FADH2 to the terminal electron acceptor. The second process, transfer of electrons, is accomplished as part of which of the following? fermentation glycolysis cellular respiration the TCA cycle the pentose phosphate pathway
fermentation cellular respiration
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
glucose glycolysis
Electron carriers of the electron transport chain are able to move protons across a membrane. They are able to do so because ______. they supply ATP, which is used in a phosphorylation reaction to move protons their protein structure includes a mobile component that physically ratchets to pump the protons across the membranes some accept only hydrogen atoms (proton-electron pairs), whereas others accept only electrons
some accept only hydrogen atoms (proton-electron pairs), whereas others accept only electrons
Enzymes function as biological catalysts, accelerating the conversion of one substance, the _____ into another the _____
substrate product
Consider the three central metabolic pathways that gradually oxidize glucose to CO2. Why are these amphibolic pathways? "Amphibolic" is another word for "catabolic," which refers to the set of processes that breaks down molecules and releases energy. "Amphi" means "both kinds," which reflects the dual role of these central metabolic pathways. The term "amphibolic" reflects that these are metabolic pathways that take place in an aqueous environment. Although they are catabolic, the precursor metabolites and reducing power they generate can be diverted for biosynthesis (anabolism).
"Amphi" means "both kinds," which reflects the dual role of these central metabolic pathways. Although they are catabolic, the precursor metabolites and reducing power they generate can be diverted for biosynthesis (anabolism).
To generate one molecule of the 6-carbon sugar fructose, how much energy and reducing power is consumed? 2 ATP and 2 NADH 1 ATP and 1 NADPH + H+ 18 ATP and 12 NADPH + H+ 6 ATP and 6 NADH
18 ATP and 12 NADPH + H+
During the transition step of central metabolism, all of the following occur EXCEPT ______. The 2-carbon acetyl group is joined to coenzyme A to form acetyl-CoA. CO2 is removed from pyruvate. Electrons are transferred to NAD+, reducing it to NADH + H+. 2 ATP are generated.
2 ATP are generated.
For each glucose molecule degraded, the net yield of glycolysis is ______. 4 ATP, 2 NADH, and 6 precursor metabolites 2 ATP and 2 NADH 2 ATP, 2 NADH, and 6 precursor metabolites
2 ATP, 2 NADH, and 6 precursor metabolites
In order to form lipids, how are fatty acids and glycerol synthesized? Fatty acid chains are taken from the electron transport chain of respiration; the precursor to glycerol comes from the TCA cycle. Fatty acid chains are assembled by linking glucose molecules; glycerol comes from the TCA cycle. Fatty acid chains come from a precursor near the end of the TCA cycle; glycerol is provided by the pentose phosphate pathway. Fatty acid chains are assembled from 2-carbon acetyl groups from the transition step; the precursor to glycerol comes from glycolysis.
Fatty acid chains are assembled from 2-carbon acetyl groups from the transition step; the precursor to glycerol comes from glycolysis.
Autotrophs use carbon dioxide (CO2) to synthesize organic compounds. Which of the following descriptions of this process are true? In photosynthetic organisms, the process is called the light-independent reactions. It is called carbon fixation. It often involves the Calvin cycle. Plants accomplish it by reversing the steps of the TCA cycle.
In photosynthetic organisms, the process is called the light-independent reactions. It is called carbon fixation. It often involves the Calvin cycle.
Which of the following are true statements about what happens to glucose inside a cell? Some glucose might be oxidized to CO2, generating the maximum amount of ATP. Some glucose might enter glycolysis, only to be siphoned off as a precursor metabolite for biosynthesis. All the glucose molecules are oxidized to CO2, generating ATP and reducing power in the process. Glucose can be used in catabolism to yield energy, or the precursor metabolites generated from its breakdown can be used in anabolism.
Some glucose might be oxidized to CO2, generating the maximum amount of ATP. Some glucose might enter glycolysis, only to be siphoned off as a precursor metabolite for biosynthesis. Glucose can be used in catabolism to yield energy, or the precursor metabolites generated from its breakdown can be used in anabolism.
Which of the following correctly describe respiration? The electron transport chain uses the electrons to generate a proton motive force that can be used to generate ATP. All organisms that grow in the presence of O2 must use respiration for their energy needs. It is only present in aerobic organisms. Electrons extracted from glucose are transferred to the electron transport chain.
The electron transport chain uses the electrons to generate a proton motive force that can be used to generate ATP. Electrons extracted from glucose are transferred to the electron transport chain.
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? They will grow aerobically until all the O2 is gone and then stop, because aerobic respiration yields the greatest energy. They will grow aerobically on the sugars, producing O2 in the process. They will grow aerobically, consume the O2 dissolved in the juice, and then switch to fermenting sugars to yield alcohol. They will grow aerobically, then switch to anaerobic respiration as the O2 level drops. They will only ferment the sugars to yield alcohol.
They will grow aerobically, consume the O2 dissolved in the juice, and then switch to fermenting sugars to yield alcohol.
Which of the following correctly describe the transition step and the tricarboxylic acid (TCA) cycle? Together they generate the most reducing power of all the central metabolic pathways. The TCA cycle oxidizes a 2-carbon acetyl group to release two molecules of CO2. The transition step converts the pyruvate from glycolysis into acetyl-CoA. The TCA cycle generates most of the ATP for the cell. The TCA cycle reduces a 2-carbon acetyl group to release two molecules of CO2.
Together they generate the most reducing power of all the central metabolic pathways. The TCA cycle oxidizes a 2-carbon acetyl group to release two molecules of CO2. The transition step converts the pyruvate from glycolysis into acetyl-CoA.
The critical site of an enzyme to which a substrate binds by weak forces is called the _____ _____
active site
Cells use ATP as the ready and immediate donor of free energy. ATP stands for _____ _____
adenosine triphosphate
The process by which chemolithoautotrophs and photoautotrophs incorporate CO2 into organic compounds is called _____ _____
carbon fixation
One component of metabolism, called _____ , involves the breakdown of compounds to release energy.
catabolism
The set of chemical reactions that degrade compounds, releasing their energy is termed ______. anabolism metabolism catabolism amensalism
catabolism
The energy released by ______ is captured by cells to make ATP; this ATP can then be used for biosynthesis, or ______. catabolism; anabolism anabolism; catabolism
catabolism; anabolism
Enzymes are biological ______ that are typically _______. catabolites; protein catalysts; protein catalysts; lipid catabolites; lipid reducters; protein
catalysts; protein
A chemical reaction that requires an input of energy in order to proceed is termed _____ , whereas one that releases energy is called _____
endergonic exergonic
The capacity to do work is the definition of _____
energy
Proteins that function as biological catalysts are called _____
enzyme
Prokaryotes are remarkably diverse in their metabolism. Many are _____ anaerobes which use O2 if it is available, but they can use an alternative if it is not.
facultative
True or false: The sole function of glucose for cells growing in a glucose-salts medium is as an energy source.
false
True or false: Enzymes are changed by the reaction as they lower the activation energy.
false Reason: Enzymes are unchanged by the reactions they catalyze, and so are free to combine with new substrate molecules.
True or false: The Calvin cycle is a two-step linear pathway that photosynthetic organisms use to fix carbon dioxide
false reason: the pathway is complex and cyclic
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? wine and beer making bread making pickles and cured sausages making biofuels Swiss cheese
wine and beer making bread making making biofuels
Recall that E. coli can grow in glucose-salts medium, which contains only glucose and a few inorganic salts. This means the glucose is serving what two purposes in the cell? A monosaccharide that the cell can assemble into polysaccharides such as cellulose for its cell wall Starting point from which all cell components are made Source of phosphate Energy source Source of nitrogen
Starting point from which all cell components are made Energy source
When a single molecule of glucose is processed by glycolysis in an E. coli cell, which of the following make up the net gain of this process? Zero precursor metabolites 2 molecules of NADH 4 molecules of ATP Six precursor metabolites 2 molecules of ATP
2 molecules of NADH Six precursor metabolites 2 molecules of ATP
For each glucose molecule, the pentose phosphate pathway yields ______. 2 molecules of NADPH and a variable number of precursor metabolites a variable amount of reducing power in the form of NADPH and 2 precursor metabolites 4 ATP, 2 NADH, and 6 precursor metabolites
a variable amount of reducing power in the form of NADPH and 2 precursor metabolites
For each molecule of glucose that enters glycolysis, the intermediate step generates two molecules of acetyl-CoA. If these both feed into the TCA cycle, the resulting two turns of the TCA cycle will generate which of the following? 2 precursor metabolites 2 ATP 2 molecules of pyruvate 6 NADH 2 FADH2 NADPH
2 precursor metabolites 2 ATP 6 NADH 2 FADH2
The pentose phosphate pathway generates which of the following from each molecule of glucose? 4 ATP 2 molecules of pyruvate 2 precursor metabolites 2 NADH A variable amount of NADPH
2 precursor metabolites A variable amount of NADPH
Which of the following accurately describe the pentose phosphate pathway? Its primary role is the production of compounds used in biosynthesis. It produces many different precursor metabolites. It yields reducing power in the form of NADPH. The final product of glycolysis feeds into the pentose phosphate pathway. It breaks down glucose.
It breaks down glucose. Its primary role is the production of compounds used in biosynthesis. It yields reducing power in the form of NADPH.
Match each of the three central metabolic pathways with the correct description. Instructions Glycolysis Pentose phosphate pathway tricarboxylic acid cycle (TCA Cycle)
glycolysis - splits glucose and gradually oxidizes it to two molecules of pyruvate; generates some ATP and reducing power plus 6 precursor metabolites pentose phosphate pathway- breaks down glucose, although primary role is production of NADPH and two precursor metabolites for use in biosynthesis TCA cycle - oxidizes an acetyl group to release two molecules of CO2; generates some ATP and precursor molecules and the most reducing power of all the central metabolic pathways
The TCA cycle turns twice for each molecule of glucose that enters glycolysis. Together, these two turns generate ______. 2 ATP and multiple precursor metabolites 2 ATP, 6 NADH, 2 FADH2, and 2 precursor metabolites 6 NADH, 2 FADH2, and 2 NADPH 34 ATP and 12 precursor metabolites
2 ATP, 6 NADH, 2 FADH2, and 2 precursor metabolites
Considering the general equation that describes photosynthesis, the rate of the process would be most influenced by the availability of _______ in the atmosphere. O2 H2 CO2 N2
CO2
What microorganisms use a fermentation pathway that results in CO2 and ethanol production? Propionibacterium species Clostridium species The group of Gram-positive lactic acid bacteria Saccharomyces species (yeast) and Zymomonas species (bacteria)
Saccharomyces species (yeast) and Zymomonas species (bacteria)
You wish to isolate some chemolithotrophs. Where might be a good place to start looking for them? As common healthcare-associated human pathogens in hospitals and nursing homes. As contaminants in the cheese making industry. Environments that are rich in organic compounds such as the surface of a compost pile or leaf matter decaying on a forest floor. Specific environments where reduced inorganic compounds are found, such as hydrothermal vents.
Specific environments where reduced inorganic compounds are found, such as hydrothermal vents.
What is the active site of an enzyme? The site of allosteric regulation of the enzyme. The site characterized by constant motion of molecules. The critical site to which a substrate binds by weak forces. The site at which ATP is generated. The site that breaks off the enzyme as it catalyzes a reaction.
The critical site to which a substrate binds by weak forces.
Microorganisms can grow on a variety of organic compounds other than glucose, including polysaccharides, proteins, and lipids. How do they accomplish this? A series of enzymatic reactions convert the proteins, lipids, and polysaccharides into glucose that can then be broken down via glycolysis They have separate metabolic pathways for these three classes of macromolecules that oxidize the compounds to CO2. They extract the glucose structures from these macromolecules and excrete the rest as waste products into the surrounding environment. They break these macromolecules down into appropriate precursor metabolites that are then introduced into central metabolism or used in biosynthesis.
They break these macromolecules down into appropriate precursor metabolites that are then introduced into central metabolism or used in biosynthesis.
True or 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.
False Reason: Actually, a single species can have several alternative carriers, allowing cells to cope with ever-changing growth conditions. E. coli is a great example, since it can respire either aerobically or anaerobically.
A cell has only a limited number of electron carrier molecules. During glycolysis, if electrons are not removed from NADH, the cell soon runs out of available NAD+, and the breakdown of glucose ends. This presents a problem for cells that lack a suitable terminal electron acceptor for the electron transport chain or that cannot respire. The solution to this problem is a process called _____
Fermentation
Consider the theoretical maximum ATP yield from the complete oxidation of glucose via aerobic respiration in prokaryotes. Match the relative contribution in terms of ATP (substrate-level phosphorylation plus oxidative phosphorylation) with the correct metabolic component. Instructions 8 ATP 6 ATP 24 ATP 38 ATP TCA cycle glycolysis total yield of aerobic respiration transition step
8 ATP - Glycolysis 6 ATP - Transition step 24 ATP - TCA Cycle 38 ATP - Total yield of aerobic respiration
Consider the three key central metabolic pathways (glycolysis, pentose phosphate pathway, and the TCA cycle). What three beneficial products of these pathways? water oxidized electron carriers large carbon polymers ATP CO2 precursor metabolites reducing power
ATP precursor metabolites reducing power
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? The electron transport chain generates a proton motive force. Electrons flow through ATP synthase to drive the synthesis of ATP. A phosphate group is removed from each NADH and FADH2. ATP synthase uses the energy of the proton motive force to drive the synthesis of ATP. The electron transport chain uses the energy in protons to transfer electrons across the membrane. The electron transport chain is oxidized by the donation of electrons from NADH and FADH2.
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.
In prokaryotes, how does the energy yield of aerobic respiration compare to anaerobic respiration? The energy yield of aerobic respiration is greater than anaerobic respiration. The energy yield from both is the same. The energy yield of aerobic respiration is less than anaerobic respiration.
The energy yield of aerobic respiration is greater than anaerobic respiration.
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? The precursor metabolites from glycerol enter glycolysis; the 2-carbon units from fatty acids are added to coenzyme A and enter the TCA cycle. Glycerol is converted to glucose; the fatty acids enter directly into the TCA cycle. The precursor metabolites from glycerol are joined together to form pyruvate; the 2-carbon units from fatty acids are combined to form glucose. The precursor metabolites from glycerol enter the pentose phosphate pathway; the fatty acids are converted to glucose and enter glycolysis.
The precursor metabolites from glycerol enter glycolysis; the 2-carbon units from fatty acids are added to coenzyme A and enter the TCA cycle.
Why does anaerobic respiration yield less energy than aerobic respiration? The terminal electron acceptors used in anaerobic respiration have lower electron affinities than O2. O2 has a much lower electron affinity than the terminal electron acceptors used in anaerobic respiration. Anaerobic respiration lacks an electron transport chain, so much less energy is extracted. Anaerobes do not perform glycolysis, so they miss out on the 2 ATP and 2 NADH that aerobes generate.
The terminal electron acceptors used in anaerobic respiration have lower electron affinities than O2.
Other than generating some ATP via the substrate-level phosphorylation steps of glycolysis, what critical role do the additional steps of fermentation accomplish? They produce end products, such as ethanol or lactic acid, which are used to inhibit the growth of competitors. They use up extra ATP so that glycolysis can continue producing additional reducing power. They consume excess reducing power in order to regenerate NAD+ so that it can accept electrons to keep glycolysis going. They generate end products such as ethanol, which the cell can then use as an energy source.
They consume excess reducing power in order to regenerate NAD+ so that it can accept electrons to keep glycolysis going.
True or false: With respect to the location of the electron transport chain, the inner membrane of mitochondria is analogous to the cytoplasmic membrane of bacterial cells.
True Reason: The electron transport chain of eukaryotic cells is in the inner membrane of mitochondria, and in bacterial cells it is in the cytoplasmic membrane. This observation is consistent with the Endosymbiotic Theory, which states that mitochondria evolved from a bacterium living within a host cell.
For each six-carbon molecule of glucose that enters glycolysis, how many molecules of pyruvate are made, and how many carbon atoms does each pyruvate have? Six molecules of pyruvate, each with one carbon atom. Two molecules of pyruvate, each with three carbon atoms. One molecule of pyruvate with six carbon atoms. Two molecules of pyruvate, each with two carbon atoms. Three molecules of pyruvate, each with two carbon atoms.
Two molecules of pyruvate, each with three carbon atoms.
Nucleotide subunits of DNA and RNA are composed of three units: a 5-carbon sugar, a phosphate group, and a nucleobase. They are initially synthesized ______. by completely separate pathways that converge near the end to yield the final ribonucleotides or deoxyribonucleotides as ribonucleotides that can be converted to deoxyribonucleotides by replacing the 2' hydroxyl group with a hydrogen atom as deoxyribonucleotides that can be converted to ribonucleotides by replacing the 2' hydrogen atom with a hydroxyl group by a mostly linear pathway that branches at the very end to yield either ribonucleotides or deoxyribonucleotides
as ribonucleotides that can be converted to deoxyribonucleotides by replacing the 2' hydroxyl group with a hydrogen atom
Purines and pyrimidines are synthesized ______. one by branched pathway, the other a cyclical pathway by the same pathway in distinctly different manners in successive order, one being made from the other
in distinctly different manners
Which is the correct order for the three stages of the Calvin cycle? incorporation → reduction → regeneration incorporation → regeneration → reduction reduction → regeneration → incorporation regeneration → incorporation → reduction reduction → incorporation → regeneration
incorporation → reduction → regeneration
The mutual interaction of substrate and enzyme is best described as a(n) ______. induced fit dynamic mutualism allosteric cooperation lock and key arrangement
induced fit
Consider the following linear metabolic pathway of a bacterial cell: Starting compound → Intermediate-a → Intermediate-b → End Product. The first two reactions are catalyzed by enzymes A and B, respectively. If a mutant cell arose that was unable to produce enzyme B, what would be the impact on the other components of the pathway? The cell could still produce intermediate-a but would be unable to produce intermediate-b or the end product. The cell would be unable to produce any of the intermediates shown. The metabolic pathway would proceed forward at the normal rate, resulting in production of the end product. The metabolic pathway would be forced to run at a higher rate to make up for the absence of enzyme B.
The cell could still produce intermediate-a but would be unable to produce intermediate-b or the end product.
Which of the following explain why a cell might undergo fermentation? The cell might not have the appropriate terminal electron acceptor available for respiration. The cell has a limited number of electron carrier molecules that must be regenerated for glycolysis to continue. The cell can obtain more ATP from this pathway than via respiration. The cell might lack the pathways for respiration, so fermentation might be the only option. This allows the cell to grow in the presence of O2, which otherwise it would be unable to do.
The cell might not have the appropriate terminal electron acceptor available for respiration. The cell has a limited number of electron carrier molecules that must be regenerated for glycolysis to continue. The cell might lack the pathways for respiration, so fermentation might be the only option.
In order for cells to obtain energy, they remove electrons from an energy source and ultimately donate them to the terminal electron acceptor. What does this tell us about the electron affinity of the energy source and the terminal electron acceptor? This information doesn't tell us anything about the electron affinities of these molecules. The energy source and the terminal electron acceptor have equal but opposite electron affinities. The energy source has a higher affinity for electrons, and the terminal electron acceptor has a lower affinity for electrons. The energy source has a lower affinity for electrons, and the terminal electron acceptor has a higher affinity for electrons.
The energy source has a lower affinity for electrons, and the terminal electron acceptor has a higher affinity for electrons.
Which of the following are true about glycolysis? The pathway provides the cell with a large amount of ATP, reducing power, and a number of precursor metabolites. The pathway provides the cell with a small amount of ATP, some reducing power, and six precursor metabolites. The pathway splits glucose and oxidizes it to form two molecules of pyruvate. The pathway splits glucose and reduces it to form two molecules of pyruvate.
The pathway provides the cell with a small amount of ATP, some reducing power, and six precursor metabolites. The pathway splits glucose and oxidizes it to form two molecules of pyruvate.
Which of the following describe enzyme specificity? The substrate must align spatially with the active site. A particular enzyme will only interact with a single class of molecule. For example, enzyme A might only interact with alcohols. Enzymes are made from the same type of macromolecule with which they interact, e.g., lipids for fats, etc. With few exceptions, a unique enzyme is required to catalyze each reaction in a cell. Each enzyme is made by a different organelle. Hydrogen and ionic bonding occur to induce the correct fit between substrate and active site.
The substrate must align spatially with the active site. With few exceptions, a unique enzyme is required to catalyze each reaction in a cell. Hydrogen and ionic bonding occur to induce the correct fit between substrate and active site.
