Wk 12 - Metabolism: Basic Concepts and Design

What is the ΔG°′ for the conversion of X → Y if the reaction X + ATP + H2O → Y + ADP + Pi has a ΔG°′ of -15.25 kJ mol-1? +30.5 kJ mol-1 -30.5 kJ mol-1 0 kJ mol-1 +15.25 kJ mol-1

+15.25 kJ mol-1 In order to have -15.25 kJ left the reaction would have to be endothermic and would have half of the ATP hydrolyzed off.

What is the net charge of NAD+? +1 -1 zero +2

-1 Add the charges of the phosphates plus the nitrogen to get the overall charge.

The phosphorylation of glucose has a ΔG°′ of +16.7 kJ mol-1. Glucose + Pi ⇌ glucose 6-phosphate What would be the ΔG°′ of the reaction if coupled to the hydrolysis of ATP? ATP + H2O → ADP + Pi ΔG°′ = -30.5 kJ mol-1 -13.8 kJ mol-1 +47.2 kJ mol-1 +16.7 kJ mol-1 +13.8 kJ mol-1

-13.8 kJ mol-1 This is the energy value after the coupled reaction has completed.

What is the net charge of FAD? -1 +1 -2 zero

-2 The only charged molecules are phosphates.

Which one of the following best indicates the expected net charge of ATP at pH 7? -4 -3 -2 -1

-4 This is the terminal phosphate charge added to two other phosphates that have a -1 charge each.

Imagine that under standard conditions, the conversion of L to M at equilibrium yields 10 times as much M as L. Which one of the following best indicates the change in free energy under standard conditions for this reaction? -6 kJ/mol 6 kJ/mol 10 kJ/mol -25 kJ/mol

-6 kJ/mol Use this in the formula RT lnKeq, where 10/1 is the equilibrium constant.

How many niacin moieties does FADH2 contain? 0 1 2 3

0 FAD is made from flavin.

In glycolysis, the isomerization of glucose 6-phosphate (G 6-P) into fructose 6-phosphate (F 6-P) has a ΔG°′ of +1.7 kJ mol—1. Calculate Keq′ at 25° for this reaction. 0.5 298.8 2.0 -0.5

0.5 A small Keq′ value is directly related to small G values.

In the lab you find the total free energy for a three-step metabolic process to be negative. The first step has a free energy of -25 kJ, and the second step has a free energy of 20 kJ. What CANNOT be the free energy of the third step? 4 kJ -4 kJ 7 kJ -7 kJ

4 kJ This could be the third step because there would be -1 kJ left for the total free energy.

Coenzyme A contains an ADP unit attached to a tail that contains 11 carbons (2 of which comprise methyl groups). How many of these carbons are derived from vitamin B5 (pantothenate)? 6 8 10 9

9 There are 9 carbons derived from pantothenate.

When paired with ion gradients, this molecule can regenerate as needed. Othrophosphates are also added to this molecule's precursor. What is this molecule? GDP UMP ATP ADP

ATP Ion gradients can help add phosphates to ADP.

Some phosphorylated compounds, such as phosphoenolpyruvate (PEP), have higher phosphoryl-transfer potential than does ATP. As a result _____. a phosphate from ATP can readily be transferred to pyruvate to form PEP ATP can be synthesized during glycolysis many organisms use PEP as their primary energy currency phosphorylation of ADP is exergonic

ATP can be synthesized during glycolysis PEP made in glycolysis can transfer its phosphate to an ADP.

Which one of the following is TRUE regarding NTPs? GTP has by far the highest free energy. All of the NTPs are energetically equivalent. CTP has by far the highest free energy. ATP has by far the highest free energy.

All of the NTPs are energetically equivalent. Even though all of the nucleoside triphosphates are energetically equivalent, ATP is still the primary cellular energy carrier.

In the lab, you have an Erlenmeyer flask filled with methane. You add about 2 mL of oxygen, and an oxidizing agent. If allowed to react fully, what is the product, and is the product oxidized or reduced? O2, reduced CO2, oxidized CO2, reduced O2, oxidized

CO2, oxidized When methane is fully oxidized it creates carbon dioxide.

Which one of the following best explains why an ester is more thermodynamically stable than a thioester? Esters have greater molecular mass. Esters have greater resonance stabilization. Esters have greater free energy under standard conditions. Esters have greater water solubility.

Esters have greater resonance stabilization. Sulfurs cannot maintain three bonds and a charge.

Imagine that, under a particular set of conditions, conversion of G to H is associated with a free-energy change of +8 kJ/mol, while conversion of J to K is associated with a free-energy change of -14 kJ/mol. Which one of the following best indicates a scenario in which conversion of G to H is favorable? The two reactions are occurring on opposite sides of a membrane. H and J are actually the same molecule. An enzyme exists to catalyze the G to H conversion. The pH is 7.

H and J are actually the same molecule. This allows the reactions to be coupled and the conversion of G to H to be favorable.

Which of the following statements about ATP is FALSE? ATP serves as the principal immediate donor of free energy. The turnover of ATP in a cell is high. In a typical cell, the half-life of a molecule of ATP is 10 minutes. The total amount of ATP in a person is about 100 grams.

In a typical cell, the half-life of a molecule of ATP is 10 minutes. The half-life of ATP is typically shorter.

Aside from involving a phosphorylation, which one of the following best describes the reaction of glyceraldehyde 3-phosphate (GAP), NAD+, and orthophosphate to produce 1,3-bisphosphoglycerate and NADH? It is a carbon oxidation reaction. It is a carbon reduction reaction. It is a hydrolysis reaction. It is a condensation reaction.

It is a carbon oxidation reaction. NAD+ is being reduced to carrier electrons.

Which one of the following is true if a particular reaction has a negative free-energy change under standard conditions, but a positive free-energy change under cellular conditions? It would not occur spontaneously under either standard or cellular conditions. It would occur spontaneously under both standard and cellular conditions. It would not occur spontaneously under standard conditions, but would occur spontaneously under cellular conditions. It would occur spontaneously under standard conditions, but not under cellular conditions.

It would occur spontaneously under standard conditions, but not under cellular conditions. Negative free energy makes the reaction spontaneous.

In the reaction pathway in which E1 catalyzes conversion of F to G, E2 catalyzes conversion of G to H, and E3 catalyzes conversion of H to J, which one of the following is the most likely allosteric inhibitor of enzyme E1? E2 F J E3

J This causes feedback inhibition for E1 to stop producing G. The first Rxn in many bio synthetic pathways is allosterically inhibited by the ultimate product of the pathway

Which one of the following best indicates what a nucleoside diphosphate kinase does? Nucleoside diphosphate kinase adds a phosphate to the terminal phosphate of an NDP. Nucleoside diphosphate kinase adds a chain of two phosphates to an NMP. Nucleoside diphosphate kinase adds two phosphates to NMP, one at each end of the molecule. Nucleoside diphosphate kinase adds a phosphate to the phosphate of an NMP.

Nucleoside diphosphate kinase adds a phosphate to the terminal phosphate of an NDP. This what the kinase does to make an NTP.

In aerobic organisms, the ultimate electron acceptor in the oxidation of carbon is _____ and the carbon oxidation product is _____. H2O; O2 H2O; CO2 O2; CO2 O2; H2O

O2; CO2 Oxygen accepts the electrons and CO2 is the oxidation product.

ATP hydrolysis is biomolecular (i.e., ATP + water becomes ADP + inorganic phosphate). Which one of the following best explains why entropy is said to be increasing in this reaction even though the total number of molecules is staying the same? One of the reactants is the same molecule as the solvent. The total mass of the products is higher than that of the reactants. ADP is more disordered than is ATP. ADP is more water soluble than is ATP.

One of the reactants is the same molecule as the solvent. More solvent molecules can increase disorder.

Which one of the following best indicates the difference between an acyl group and an acetyl group? Only an acetyl group contains carbon. Only an acetyl group lacks sulfur. Only an acetyl group has a defined number of carbons. Only an acetyl group can be carried by a CoA molecule.

Only an acetyl group has a defined number of carbons. Acyl has no defined number of carbons.

Which of the following is TRUE of the resonance structures of orthophosphate? The presence of so many resonance structures makes the energy of hydrolysis of pyrophosphate greater than for ATP. Exactly three resonance structures are possible. Orthophosphate has greater resonance stabilization than ATP. Exactly two resonance structures are possible.

Orthophosphate has greater resonance stabilization than ATP. In ATP the number of interconnected phosphates limits resonance.

Which of the following best helps to explain the high phosphoryl-transfer potential of ATP? The γ phosphate has a net charge of -1. ATP has higher entropy than its hydrolysis products. ATP occupies a lower volume than does ADP. Pi has more resonance forms than any of the phosphoryl groups of ATP.

Pi has more resonance forms than any of the phosphoryl groups of ATP. ATP has phosphoanhydride bonds which prevent further resonance.

Which one of the following is TRUE regarding vitamins? Some vitamins are metal ions. All vitamins are coenzymes. All vitamins contain adenine. Some vitamins are necessary for production of electron carriers.

Some vitamins are necessary for production of electron carriers. NAD and FAD are made from vitamins.

Why does the oxidation of glyceraldehyde 3-phosphate to 3-phosphoglyceric acid NOT occur directly (in one step) in cells? The free energy associated with a direct oxidation to 3-phosphoglycerate is more negative than that associated with the generation of an acyl phosphate. The energy of oxidation is initially trapped as a high-phosphoryl-transfer-potential compound and then used to form ATP. The enzyme that can oxidize glyceraldehyde 3-phosphate directly is not in the same compartment of the cell in which glyceraldehyde 3-phosphate is found. High concentrations of NADH in the cell will drive the formation of 1,3-bisphosphoglycerate at rates greater than the rate at which direct oxidation of glyceraldehyde 3-phosphate can occur.

The energy of oxidation is initially trapped as a high-phosphoryl-transfer-potential compound and then used to form ATP. The trapped phosphoryl energy makes this process greater than one step.

If a reaction has a change in free energy under standard conditions of +30 kJ/mol, then which one of the following best indicates the value of the equilibrium constant for the reaction? The equilibrium constant will have a negative value very far from zero. The equilibrium constant will have a very low positive value. The equilibrium constant will have a very high positive value. The equilibrium constant will have a negative value very close to zero.

The equilibrium constant will have a very low positive value. The signs of the equilibrium constant and the G value are the same, as well are their proportions.

A metabolic pathway must satisfy which of the following requirements to properly function? The overall reaction of the pathway must be thermodynamically favored. ATP must be a reactant in the pathway. The individual reactions must each be thermodynamically favored. The individual reactions must each be at equilibrium.

The overall reaction of the pathway must be thermodynamically favored. This allows a metabolic system to create enough energy.

Under standard conditions, is it more likely that ATP will be hydrolyzed to ADP or that acetyl CoA will be hydrolyzed to acetate and CoA? Acetyl CoA hydrolysis is thermodynamically favorable, whereas ATP hydrolysis is not. They are both thermodynamically favorable; the rate for each reaction will be independent of whether a catalyst is present. ATP hydrolysis is thermodynamically favorable, whereas acetyl CoA hydrolysis is not. They are both thermodynamically favorable; the rate for each reaction will depend on whether a catalyst is present.

They are both thermodynamically favorable; the rate for each reaction will depend on whether a catalyst is present. A catalyst is the only thing that would change the rate of the reaction since both are favorable at standard conditions.

A metabolic pathway consisting of five reactions U → V → W → X → Y → Z has been proposed. The ΔG°′ for each reaction is shown below. Which of the following statements is TRUE regarding this proposed pathway? U → V ΔG°′ = -15kJ/mol V → W ΔG°′ = -2kJ/mol W → X ΔG°′ = +5kJ/mol X → Y ΔG°′ = +6kJ/mol Y → Z ΔG°′ = -7kJ/mol This pathway may occur because the largest ΔG°′ is a negative number. This pathway would not take place. The first two reactions of the pathway will occur, but once W is formed the pathway will halt. This pathway may occur because the overall ΔG°′ is negative.

This pathway may occur because the overall ΔG°′ is negative. Since G total was negative, it means the reaction occurs spontaneously.

Which one of the following contains sulfur? glucose pyruvate lactate acetyl CoA

acetyl CoA The sulfur is from the carrier molecule that was bound to CoA.

CoA is an important carrier of _____ groups in metabolism. hydroxyl sulfhydryl methyl acyl

acyl Any multicarbon attachment to CoA can be transferred.

Metabolic reactions that require energy, such as the synthesis of DNA, are called _____ reactions. anabolic anaplerotic amphibolic amphipathic

anabolic These reactions require energy to build molecules.

Metabolic reactions that release energy are called _____ reactions. amphibolic anabolic catabolic cationic

catabolic This is the metabolic process that breaks down molecules to energy.

Which one of the following is both catabolic and aerobic? conversion of glucose to glycogen conversion of pyruvate to glucose conversion of glucose to pyruvate conversion of pyruvate to acetyl CoA

conversion of pyruvate to acetyl CoA Lactate is formed in anaerobic conditions.

What energy molecule is needed for repetitive exercise after ATP is used up? pyrophosphate GTP UMP creatine phosphate

creatine phosphate This molecule starts giving more energy back to ATP as well as supplying your muscles.

A reaction's equilibrium constant and change in free energy under standard conditions are related by a log function. More specifically, the log function is in base _____. 10 e 2 1

e e is the natural log.

In the lab you have one flask of ethanol and one flask of ethanoic acid. If an oxidation agent was dropped into each one, which one would finish first? ethanoic acid both neither; there's no reaction ethanol

ethanoic acid Ethanoic acid is the most oxidized so it would finish oxidizing first.

In a cyclized glucose molecule, how many carbons are directly bonded to exactly one oxygen? one five three zero

five C-1 out of the six carbon atoms is attached to two oxygen atoms.

Several ring-containing structures are found in carrier molecules in metabolism. Which one of the following correctly puts them in order from highest number of rings to lowest number of rings? nicotinamide > adenine > flavin flavin > adenine > nicotinamide nicotinamide > flavin > adenine adenine > nicotinamide > flavin

flavin > adenine > nicotinamide Flavin has the most rings.

What is the name of the compound shown? This is a three-carbon structure with an aldehyde group on the top and a phosphate attached to the last carbon. There is a hydroxide on the middle carbon on the right, the hydrogen ion is on the left, and a carbon with a phosphate is bonded to a hydroxide and a hydrogen, but their arrangement is not shown. 1,3-bisphosphoglycerate glyceraldehyde 3-phosphate 3-phosphoglyceric acid 1-phosphoglyceric acid

glyceraldehyde 3-phosphate There is no carboxylic acid, just aldehyde and a phosphate.

Which of the following correctly lists compounds in increasing order of phosphoryl-transfer potential? glycerol 3-phosphate < ATP < 1,3-bisphosphoglycerate phosphoenolpyruvate < creatine phosphate < ATP glucose 6-phosphate < creatine phosphate < glycerol 3-phosphate ATP < 1,3-bisphosphoglycerate < glucose 6-phosphate

glycerol 3-phosphate < ATP < 1,3-bisphosphoglycerate 1,3-Biphosphoglycerate has the most energy out of all three of these, then ATP, and finally glycerol 3-phosphate.

What kind of reaction is needed to convert ATP to NAD? oxidation group transfer isomerization hydrolytic

group transfer This involves transferring the third phosphate to a different molecule and the niacin onto the ADP.

When energy charge is high, ATP concentration is _____ and _____ is favored. low; anabolism high; catabolism high; anabolism low; catabolism

high; anabolism Since the amount of ATP is high, anabolism is favored because of its need to use ATP.

Which one of the following features best explains why ATP is unlikely to spontaneously hydrolyze in the absence of a suitable enzyme? its negative charges its large size the H-bonding ability of its purine its small size

its negative charges The phosphate charges keep it from hydrolyzing.

The reaction below is an example of which type of reaction? Pyruvate is mixed with carbon dioxide, ATP, and water to form oxaloacetate, ADP, an orthophosphate (Pi), and a hydrogen cation. isomerization group transfer oxidation-reduction ligation

ligation A new carbon-carbon bond was formed.

Which of the following has the largest negative ΔG°′oxidation? formic acid formaldehyde methane methanol

methane The more reduced a carbon is to begin with, the more free energy is released by its oxidation, and out of these four answer choices methane is the most reduced molecule.

Which group lists the molecules in the CORRECT order from the most negative ΔG°′ of oxidation to the least negative ΔG°′ of oxidation? methanol, formaldehyde, carbon dioxide methane, formic acid, methanol methane, carbon dioxide, formaldehyde formaldehyde, formic acid, methanol

methanol, formaldehyde, carbon dioxide Carbon dioxide has a ΔG°′ of 0 so it will be listed last in the list, and methanol has the most negative ΔG°′ so it will listed first.

Which one of the following BEST indicates the reactants that are used in the ATP synthesis reaction when fuel molecules are being used? one AMP and two orthophosphates one adenosine and three orthophosphates one ADP and one orthophosphate one AMP and one pyrophosphate

one ADP and one orthophosphate Orthophosphate Pi is higher in energy and traps that energy in the bond after being added to ADP.

In NAD+, which one of the following specifically carries the positive charge that is absent in NADH? one specific nitrogen out of several that exist in the molecule the only nitrogen the only phosphorus one specific phosphorus out of several that exist in the molecule

one specific nitrogen out of several that exist in the molecule It is on the nitrogen that is from the niacin molecule.

If the first stage is digestion, and the second stage is where fuel is broken down to the basic units, what is the third stage? oxidative phosphorylation of ATP reduction of ATP oxidation of ATP Krebs cycle

oxidative phosphorylation of ATP Acetyl CoA is used up after it is obtained from stage two.

Which ion is unique for the human body's processes? arsenate citrate silicate phosphate

phosphate Phosphate and its esters have many properties that enable them to be useful for biochemical systems.

In life forms most of the ATP synthesis is powered by either oxidation of fuel molecules or by _____. pyrophosphate hydrolysis reduction of fuel molecules photosynthesis ATP synthase

photosynthesis Phototrophs use photosynthesis to make ATP.

In the lab you have four containers filled with the various chemicals in the answer list. Which one is the most reduced? carbon dioxide propane propanol propanoic acid

propane Propane contains no oxygen; thus, it will be the most reduced form.

Which one of the following flows down its concentration gradient in order to power an ATP-synthesizing enzyme? ADP ATP protons orthophosphate

protons Proton gradients generated by the oxidation of carbon fuels account for more than 90% of ATP generation.

Glucose can be metabolized in 10 steps to _____, which can then be processed further either aerobically or anaerobically. acetyl CoA lactate pyruvate NADH

pyruvate Pyruvate is a product of glycolysis, and can be metabolized.

Biosynthetic reactions tend to require _____ as well as ATP. proteases proton gradients reducing power manganese

reducing power Some precursors are oxidized and need reduction first.

NADPH is used almost exclusively for _____, whereas NADH is primarily used for generation of _____. reductive biosyntheses; ATP oxidative biosyntheses; glycogen reductive biosyntheses; glycogen biosyntheses that do not involve redox reactions; heat

reductive biosyntheses; ATP NADPH reduces chemical components, and NADH makes ATP.

Which of the following modes of metabolic regulation occurs MOST quickly? upregulation of β-galactosidase following addition of lactose to a growth medium of E. coli upregulation of glucose transporters to the cell surface following insulin binding to the insulin receptor synthesis of a protease inhibitor that blocks the breakdown of an important metabolic enzyme reversible covalent modification of glycogen phosphorylase following glucagon binding to a liver cell receptor

reversible covalent modification of glycogen phosphorylase following glucagon binding to a liver cell receptor This does not have any protein synthesis.

All of the following contain ADP EXCEPT_____. riboflavin NADH FADH2 ATP

riboflavin This contains no phosphates at all.

For metabolism to be efficient, it is important that an electron carrier like NADH react _____ with oxygen in the absence of a catalyst, and that ATP be hydrolyzed _____ in the absence of a catalyst. quickly; quickly quickly; slowly slowly; slowly slowly; quickly

slowly; slowly Anaerobically the process will occur slowly, but it will still occur since it is thermodynamically favored.

What stage is the Krebs cycle a part of in the processes of energy conversion in higher organisms? stage 1 stage 4 stage 2 stage 3

stage 3 In stage 3 the Krebs cycle uses acetyl CoA before ATP is regenerated.

Which one of the following best describes the "nature" of the reactant and product in the conversion of reactant F to product G? the free energy of G minus the free energy of F [G] minus [F] the activation energy of the reaction the free energy of the transition state

the free energy of G minus the free energy of F This is the total change in free energy for the reaction.

Which of the following is a way that phosphoryl transfer can be used in a biological organism? to serve as a signal to alter the activity of a carbohydrate to drive thermodynamically favorable reactions to alter the conformation of a protein to change an enzyme's shape

to alter the conformation of a protein ATP is an activated carrier of phosphoryl groups because phosphoryl transfer from ATP is an exergonic process. Many activated carriers function as coenzymes.

What are gradients used for in cells? to pump ions such as Ca2+ into cells to power the synthesis of most of the ATP in the cell to signal to neighboring cells to transport nutrients such as lipids and amino acids into cells

to power the synthesis of most of the ATP in the cell Coupled with ATP synthesis, gradients account for most ATP

When reduced, NAD+ can carry _____ electrons and FAD can carry _____ electrons. four; four one; one one; two two; two

two; two Electron carriers carry pairs of electrons.

What vitamin is mixed with ADP to make FAD? vitamin B6 vitamin B3 vitamin B2 vitamin B5

vitamin B2 This is riboflavin, which makes FAD.

ADP is one of the precursors to activated carriers. What vitamin makes the most common activated carrier? vitamin B3 vitamin B9 vitamin B6 vitamin B5

vitamin B3 This is niacin, which makes NADH by combining with ADP.

What is this vitamin? This vitamin contains a phenol ring with carbon three being replaced by a NH group. The positive charge is on the nitrogen, and the COO- group is on carbon one on the right side of the ring. vitamin B5 (panthothenate) vitamin A (retinol) vitamin B3 (niacin) vitamin D2 (ergocalciferol)

vitamin B3 (niacin) Niacin contains the amide ring and the charged COO.