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Smartwork - Chapter 13

Terms in this set (50)

The pyruvate dehydrogenase complex plays an important role in cellular metabolism by connecting
_____ to ______.
Glycolysis, TCA cycle

First part is correct! Pyruvate is converted by the pyruvate dehydrogenase complex into acetyl-CoA.

Second part is correct! Pyruvate dehdyrogenase converts pyruvate into acetyl-CoA, which can be further oxidized in respiring organisms via the TCA cycle.
Fermentation pathways have the __________ in common.

A. oxidation of NADH to NAD+
B. production of ethanol
C. production of lactic acid
D. use of oxygen as an electron acceptor
oxidation of NADH to NAD+
All fermentation pathways regenerate NAD+ for use in glycolysis. Fermentation uses an organic compound, such as pyruvate, as an electron acceptor. The specific products differ depending on the fermentation pathway.
The first step of the EMP and ED pathways of glucose catabolism that converts glucose into glucose 6-phosphate had a ΔGo' of 14.3kJ/mol. It is coupled with the hydrolysis of ATP to ADP, which has a ΔGo' of -31kJ/mol. What is the ΔGo' of the coupled reaction?

A. 16.7 kJ/mol
B. -16.7 kJ/mol
C. 443.3 kJ/mol
D. -45.3 kJ/mol
-16.7 kJ/mol
Compost piles are typically very warm (approximately 60ºC or 141ºF) because reactions that oxidize the organic material:

A. have a positive ∆H and a negative ∆S.
B. have a negative ∆H and a negative ∆S.
C. have a negative ∆H and a positive ∆S.
D. have a positive ∆H and a positive ∆S.
negative delta H
Be able to label the TCA cycle with correct substrates and key intermediates.
Label Pyruvate, Acetly-CoA, Acetate, Citrate, 2-Oxyglutarate, succinyl-CoA, oxaloacetate
Correctly label the following illustration of movement of energy through Earth's biosystem.
Correct; during these biological transformations, a significant fraction of the system's energy is lost as heat. Therefore, even though life temporarily increases order, the overall state of the universe tends toward increased disorder (i.e., entropy).
If a small molecule is found at greater concentration inside the cell than outside, it can be concluded that

A. energy was required to produce the concentration gradient.
B. this represents the maximal entropy state for that molecule.
C. the molecule can freely move across the cell membrane.
D. the concentration gradient cannot be used to do work.
Concentration gradients are a form of potential energy that can be used to do work for the cell. In order to produce an ordered state, such as a concentration gradient, energy is required. The maximal entropy state occurs when the molecule is present at equal concentrations on either side of the membrane.

Energy was required to produce the concentration gradient
Which of the following industries does NOT use fermentation products?

A. Weapons production
B. Solar energy production
C. Fuel production
D. Food industry
Solar energy products
An organism that gets its energy from light is known as a
______. These organisms also usually grow as autotrophs, meaning that they require carbon in the form of
_______.
Phototrophs is correct! In contrast, chemotrophs use chemical forms of energy (e.g., glucose). Familiar phototrophs include plants, algae, and cyanobacteria. The "light reactions" of photosynthesis provide both the energy (ATP) and reducing power (NADPH) required for carbon fixation.

CO2 is correct! Most autotrophs, including plants and cyanobacteria, incorporate CO2 into organic molecules via the Calvin cycle (aka light-independent reactions of photosynthesis).
After completion of a turn of the tricarboxylic acid (TCA) cycle, most of the energy originally present in glucose is now found in

A. NADH.
B. pyruvate.
C. ATP.
D. carbon dioxide.
NADH
At the end of one turn of the TCA cycle only four ATPs have been produced. During the TCA cycle the carbons in the acetyl group of acetyl-CoA become oxidized and NADH is produced. NADH will release its energy to form ATP through electron transport systems. Carbon dioxide is a low-energy waste product. Pyruvate is the end product of EMP and Entner-Doudoroff pathways.
Fermentation and respiration represent two major forms of ______
in chemoorganoheterotrophs.
catabolism,

respiration and fermentation are two basic strategies that chemoorganoheterotrophs use to catabolize organic carbon sources. Respiring organisms use an external electron acceptor (such as oxygen), whereas fermenting cells transfer electrons to a partially oxidized organic product (such as pyruvate to make lactate).
ATP transfers energy to cell processes through all EXCEPT

A. hydrolysis with release of pyrophosphate.
B. phosphorylation of organic molecules.
C. glucose catabolism.
D. hydrolysis releasing of phosphate.
glucose catabolism
The TCA cycle can be used for the complete oxidation of organic carbon in respiring organisms. This is obvious by observing that one full "turn" of the cycle releases ______
molecules of _______.
2, CO2
How does temperature affect the Gibbs free energy change of a reaction in which entropy increases?

A. As temperature decreases, it makes the ΔG more negative.
B. As temperature increases, it makes the ΔG more negative.
C. As temperature increases, it makes the ΔG more positive.
D. Temperature has no effect.
As temperature increases, it makes the ΔG more negative.
Ultimately, respiration and fermentation are simply different ways to conclude sugar catabolism. Following the energy-yielding reactions, respiring cells pass electrons to oxygen (or other external inorganic oxidant), while fermenting cells dump electrons back onto a partially oxidized organic molecule (such as pyruvate), which then exits the cell as a waste product. Either way, the goal is to do which of the following?

A. fully oxidize NADH into CO2 and H2O
B. recycle NADH back to NAD+
C. generate as much NADH as possible (then synthesize more NAD+ if necessary)
D. break down NADH into biosynthetic precursors
E. stimulate de novo production of NAD+
recycle NADH back to NAD+
Although many organisms (including eukaryotes) use the Embden-Meyerhof-Parnas (EMP) pathway for the initial catabolism of glucose, alternative glycolytic pathways do exist and are widespread among the prokaryotes. The Entner-Doudoroff (ED) pathway, for example, is widely used among Gram-negative bacteria (including E. coli) and archaea. Because the EMP generates slightly more energy, it has been considered the "better" and "more evolved" of the two. But is this assumption naive?

Of the following, which phenotype would most likely be observed in mutants of E. coli lacking a key enzyme in the ED pathway?

A. loss of ability to grow anaerobically
B. lack of flagellar motility
C. reduced ability to colonize the mammalian gut
D. inability to form biofilms
E. increased virulence
Reduced ability to colonize the mammalian gut
Which metabolic pathway has ribulose-5-phosphate as an intermediary?

A. Entner-Doudoroff pathway
B. Glycolysis
C. Tricarboxylic acid cycle
D. Pentose-phosphate pathway
Ribulose-5-phosphate is an intermediary in the pentose-phosphate pathway.
Respiration
High ATP yiekd most from oxidatative phoporylation. Most carbon released as CO2. Electrons reduce an external electron acceptor (O2)
Fermentation
Low ATP yield primarily from glycolysis. Electrons from catabolism end up back on partially oxidized substrate. Most carbon remains in organic form
Respiration & Fermentation
Important for catabolism of sugars. NADH major eletron carriers. Pyruvate is an intermiediate step.
Lactic acid fermentation is so named because lactic acid is which of the following?

A. key intermediate
B. intermediate electron carrier
C. starting substrate
D. end product
E. source of energy
End Product
ATP
...
NADH
...
ATP & NADH
...
Ethanolic fermentation results in which of the following end product(s)?

A. acetone
B. lactic acid
C. carbon dioxide
D. alcohol
E. oxygen
F. water
CO2, Alcohol
Please correctly label the molecular components of NAD+ and FAD.
...
Sugars are used by many chemoheterotrophs as an important source of carbon and energy. Indeed, complete oxidation of glucose using oxygen as a terminal electron acceptor has a free energy change of -2,883.0 kJ/mol. What strategy do cells use to minimize the amount of that energy that is lost as heat during the catabolism of sugars?

A. Energy is harvested using a series of smaller oxidations.
B. The cells employ high-capacity energy carriers (e.g., ΔG°' of hydrolysis ~ -1000 kJ/mol).
C. Oxidation is directly coupled to biomass synthesis.
D. The oxidation reaction occurs within insulated organelles.
E. Oxidations of sugars directly power membrane-bound ATP synthases.
Energy is harvested using a series of smaller oxidation series
Label the image illustrating how glucose is metabolized during aerobic respiration.
notice that complete oxidation releases all the carbon in glucose (a 6C sugar) as CO2. Also, although the theoretical maximum yield of ATP is 38 per glucose, a well-oxygenated culture of E. coli typically makes only about 20 ATP per molecule of glucose.
Catabolism occurs in a series of oxidation steps to

A. minimize the heat buildup in the cell.
B. equalize the concentrations of reactants and products.
C. allow smaller energy changes and the reduction of energy carriers like NADH to couple all energy providing to energy spending reactions.
D. prevent a buildup of reactive oxygen species (ROSs) in the cytoplasm.
allow smaller energy changes and the reduction of energy carriers like NADH to couple all energy providing to energy spending reactions.
Which of the following pathways would be fully operational only in respiring bacteria?

A. TCA cycle
B. glycolysis
C. nucleotide biosynthesis
D. pentose phosphate pathway (PPP)
E. gluconeogenesis
TCA Cycle
What is a common occurrence in the three different glucose-to-pyruvate catabolic pathways?

A. Phosphorylated sugars are present.
B. NADH is oxidized to NAD+.
C. Glucose is reduced by the addition of hydrogen atoms.
D. There is no net production of ATP.
Phosphorylated sugars are present.
According to the second law of thermodynamics, systems naturally progress toward a state of increased _________
(i.e., internal randomness). Therefore, cells must acquire and use ________
to become more organized.
entropy, energy
Why does the process of acquiring nutrients from a more dilute external environment require expenditure of energy by the cell?

A. Entropy is increased.
B. Enthalpy is increased.
C. Entropy is decreased.
D. Enthalpy is decreased.
Entropy is increased
Identify the three main catabolic routes in bacteria by which glucose is converted to pyruvate.

A. Krebs cycle
B. pentose phosphate pathway
C. Embden-Meyerhof-Parnas pathway
D. Entner-Doudoroff pathway
E. electron transport chain
F. Calvin cycle
B. pentose phosphate pathway
C. Embden-Meyerhof-Parnas pathway
D. Entner-Doudoroff pathway
Which of the following molecules must be degraded by aromatic catabolism?

A. Glycerol
B. Lignin
C. Glucose
D. Acetate
Lignin
Bioremediation of certain pollutants (such as aromatic hydrocarbons) may be effectively accomplished via syntrophy, involving which of the following?

A. Different enzymes catalyzing the same reactions
B. Competition between microbes
C. Cooperation among members of the same species
D. Different species of microbes catalyzing sequential reactions
E. Different organisms catalyzing the same reactions
Different species of microbes catalyzing sequential reactions
Animals and most microorganisms are classified as chemoorganoheterotrophs. The prefixes "chemo," "organo," and "hetero" refer to how the organism meets its needs, respectively, for:

A. carbon, energy, and electrons
B. electrons, carbon, and energy
C. energy, electrons, and carbon
D. carbon, electrons, and energy
E. electrons, energy, and carbon
energy, electrons, and carbon
Lignin, which is utilized by many soil bacteria and fungi, is an example of which type of organic molecule?

A. peptide
B. lipid
C. disaccharide
D. natural gas
E. aromatic
aromatic
A reaction will be spontaneous at all temperatures if which of the following conditions are met?

A. Both ΔH and TΔS are negative.
B. TΔS is positive and ΔH is negative.
C. ΔH is positive and TΔS is negative.
D. Both ΔH and TΔS are positive.
TΔS is positive and ΔH is negative.
Which of the following is NOT a pathway to convert glucose into pyruvate?

A. Tricarboxylic acid cycle
B. Glycolysis
C. Pentose-phosphate pathway
D. Entner-Doudoroff pathway
TCA Cycle
Which one of the following is a catabolic process carried out by bacteria?

A. breakdown of starch
B. cell division
C. rotating flagella
D. synthesizing DNA
E. Calvin cycle
Breakdown starch
Entropy is a measure of __________ in a system.

A. disorder
B. free energy
C. available energy
D. total energy
Disorder
In addition to generating reducing power (i.e., NADPH) for biosynthesis, the pentose phosphate pathway also provides precursors for synthesis of which of the following? (Select all that apply.)

A. acetic acid
B. aromatic amino acids
C. citric acid
D. nucleic acids
E. fatty acids
aromatic amino acids, nucleic acids
Label the image illustrating the routes by which cells convert glucose to pyruvate and obtain important intermediates. Below each pathway, targets are provided to indicate the net yield of reducing power (NADH and/or NADPH) and ATP.
...
An example of catabolism is

A. glucose oxidation to pyruvate.
B. lipid synthesis from fatty acids and glycerol.
C. starch production from glucose.
D. amino acid polymerization into proteins.
glucose oxidation to pyruvate.
If one molecule of glucose were fully catabolized via aerobic respiration to CO2 and H2O, the ATP yield would be roughly _______
that obtained from fermentation.
20 times
Which of the following is FALSE regarding chemolithotrophic microorganisms?

A. They include methanogens.
B. They use inorganic compounds as electron donors.
C. Electron donors for respiration include Fe2+, H2S, and NH+4.
D. Light absorption provides them with electrons.
Light absorption provides them with electrons.
Which of the following energy carriers is/are generated by TCA reactions?

A. ATP (or GTP)
B. NADH
C. FADH2
D. glyceraldehyde 3-P
E. phosphoenolpyruvate
A. ATP (or GTP)
B. NADH
C. FADH2
Which of the following pathways would be preferentially used by a cell running low on energy?

A. Calvin cycle
B. glycolysis
C. pentose phosphate pathway
D. gluconeogenesis
E. nitrogen fixation
glycolysis
Which common pathway is used for the final catabolism of aromatic molecules?
TCA (tricarboxylic acid cycle)
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