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105 terms

intro to cell chapter 9

STUDY
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Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?
gamma-phosphate (the terminal phosphate)
look at diagrams in introduction to atp and redox reactions...
....
The reaction A --> B + C + heat is released in a(n) _____ reaction.
exergonic
A(n) _____ reaction occurs spontaneously
exergonic
Which of these reactions requires a net input of energy from its surroundings?
-endergonic
-hydrolysis
-ATP --> ADP + P
-catabolic
-exergonic
endergonic
In cells, what is usually the immediate source of energy for an endergonic reaction?
ATP
The reaction ADP + P --> ATP is a(n) _____ reaction.
endergonic
The energy for an endergonic reaction comes from a(n) _____ reaction.
exergonic
What is the fate of the phosphate group that is removed when ATP is converted to ADP?
It is acquired by a reactant in an endergonic reaction.
Select the INCORRECT association.
-potential energy ... positional energy
-kinetic energy ... motion
-exergonic ... spontaneous
-enzyme ... protein
-exergonic ... uphill
exergonic ... uphill
What is energy coupling?
exergonic reaction to drive an endergonic reaction
Which term describes the degree to which an element attracts electrons?
electronegativity
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
-Ionic and covalent.
-Polar and nonpolar.
-Anion and cation.
-Proton and electron.
anion and cation
Which of the following statements is true of the bonds in a water molecule?
-Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.
-Oxygen acts as the electron acceptor and is oxidized.
-There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero.
-The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1.
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.
Which of the following statements is not true of most cellular redox reactions?
-Changes in potential energy can be released as heat.
-A hydrogen atom is transferred to the atom that loses an electron.
-The electron acceptor is reduced.
-The reactant that is oxidized loses electrons.
A hydrogen atom is transferred to the atom that loses an electron.
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
ionic
Gaseous hydrogen burns in the presence of oxygen to form water:

2H2 + O2 → 2H2 O + energy

Which molecule is oxidized and what kind of bond is formed?
hydrogen, polar
What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?
hydrolysis
Oxidation and reduction reactions are chemical processes that result in a gain or loss in _______________
electrons
When an atom or molecule gains one or more electrons, it is said to be ______________ and is at a ____________ energy state.
reduced.....higher
Considering the standard reduction potential (SRP), which of the following molecules is storing the most energy?
-FMN (SRP -0.111 Volts)
-cytochrome b-c1 (SRP +0.247 Volts)
-NADH (SRP -0.322 Volts)
-cytochrome a3 (SRP +0.624 Volts)
NADH (SRP -0.322 Volts)
Considering the standard reduction potential (SRP), which of the following molecules would be the strongest oxidizing agent?
-NADH (SRP -0.322 Volts)
-FMN (SRP -0.111 Volts)
-cytochrome a3 (SRP +0.624 Volts)
-cytochrome b-c1 (SRP +0.247 Volts)
cytochrome a3 (SRP +0.624 Volts)
Considering the standard reduction potential (SRP), which of the following molecules would be the strongest reducing agent?
-FMN (SRP -0.111 Volts)
-NADH (SRP -0.322 Volts)
-cytochrome b-c1 (SRP +0.247 Volts)
-cytochrome a3 (SRP +0.624 Volts)
NADH (SRP -0.322 Volts)
In ther fermentation reaction shown below, pyruvate (pyruvic acid) is being _________ and NADH is being _______________
reduced......oxidized
Glucose is taken up into cells through a carrier (transport) protein called a _________ transporter
GLUT
Immediately after Glucose enters the cell it is phosphorylated by the enzyme __________, which adds a phophate from ATP to Glucose to produce Glucose -6- phospahte and ______________
hexokinase, ADP
A key enzyme in glycolysis, whose catalytic activity is controlled by feedback regulation is ____________________. This enzyme balances the need for energy with the production of ATP.
phosphofructokinase
When the ATP to ADP+AMP ratio is high (indicating high energy charge) the excess ATP binds to an _______________ site on the enzyme and the binding causes a overall shape change that alters the active site in such as way that _______________ the binding of substrate. The effect of this regulation slows the production of the oxidative metabolism during times when the cell has more than enough energy carrier molecules available to fuel the endogonic biochemical work of the cell
allosteric, inhibits
When the ATP to ADP+AMP ratio is low (indicating low energy charge) the excess _________ binds to an _______________ site on the enzyme and the binding causes a overall shape change that alters the active site in such as way that enhances the binding of substrate. The effect of this regulation speeds the production of the oxidative metabolism during times when the cell has inadequate number of energy carrier molecules available to fuel the endogonic biochemical work of the cell
ADP, allosteric
Rank the following molecules from highest to lowest energy
-pyruvate
-ATP
-1.3-bisphosphoglycerate
-3-phosphoglycerate
(highest) 1.3-bisphophoglycerate, 3-phosphoglycerate, pyruvate, ATP (lowest)
In enzymatic step 3 of the Krebs (Citric Acid) Cycle ____________ is the reducing agent, whereas _____________ is the oxidizing agent.
isocitrate, NAD+
In enzymatic step 6 of the Krebs (Citric Acid) cycle what is removed from the substrate Succinate?
2 hydrogen atoms
Which of the following molecules contains the highest amount of potential energy?
-Glyceraldehyde-3-Phosphate
-Glucose-6-Phosphate
-1,6 Fructose bisphosphate
-Fructose-6-Phosphate
-Glucose
1,6 fructose bisphosphate
Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy?
Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O).
Which of the following statements describes the results of this reaction?
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy
-C6H12O6 is oxidized and O2 is reduced.
-CO2 is reduced and O2 is oxidized
-C6H12O6 is reduced and CO2 is oxidized.
-O2 is oxidized and H2O is reduced.
-O2 is reduced and CO2 is oxidized.
C6H12O6 is oxidized and O2 is reduced.
Which of the following statements describes NAD+?
-In the absence of NAD+, glycolysis can still function.
-NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
-NAD+ has more chemical energy than NADH.
-NAD+ can donate electrons for use in oxidative phosphorylation.
-NAD+ is oxidized by the action of hydrogenases.
NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
Where does glycolysis take place in eukaryotic cells?
cytosol
The ATP made during glycolysis is generated by _________.
substrate-level phosphorylation
Substrate-level phosphorylation account for approximately waht percentage of the ATP formed by the reactions of glycolysis?
100%
During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is...
retained in the two pyruvates
Pyruvate Process either by a fermentation reaction or by entry to the Krebs cycle and subsequent oxidative phosphorylation, is essential to prevent glycolysis from grinding to a halt. The key need for pyruvate process is to regenrate ________________.
NAD+
The transport of pyruvate into mitochondria depends on the proton-motive force across the inner mitochondrial membrane. How does pyruvate enter the mitochondrion?
active transport
Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2) from one molecule of pyruvate?
-acetly CoA
-glyceraldehyde-3-phosphate
-lactate
-oxaloacetate
-citrate
acetyl CoA
During cellular respiration, acetyl CoA accumulates in which location?
mitochondrial matrix
How many carbon atoms are fed into the Krebs (citric acid)cycle as a result of the oxidation of one molecule of pyruvate?
two
Both ADP and _____________ bind to an allosteric site on the enzyme phosphofructokinase and increase the catalytic efficiency of the enzyme.
AMP
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of
non-competitive allosteric regulation
The Acetyl CoA molecule which brings the 2 carbon acetyl group into the Krebs cycle is produced by the _____________ and decarboxylation of _______________.
oxidation....pyruvate
What fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle, if glucose is the sole energy source?
2/3
look at diagrams in part 5 of glycolysis, pyruvate processing and...
....
In what location in the cell does glycolysis occur?
cytosol
In what location in the cell does acetyl CoA formation occur?
mitochondrial matrix
In what location in the cell does the citric acid cycle occur?
mitochondrial matrix
In what location in the cell does oxidative phosphorylation occur?
inner mitochondrial membrane
look at diagrams in part 6 of glycolysis, pyruvate processing and...
....
When a compound donates (loses) electrons, that compound becomes _______. Such a compound is often referred to as an electron donor.
oxidized
When a compound accepts (gains) electrons, that compound becomes _______. Such a compound is often referred to as an electron acceptor.
reduced
In glycolysis, the carbon-containing compound that functions as the electron donor is _______.
glucose
Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called _______.
pyruvate
_______ is the compound that functions as the electron acceptor in glycolysis.
NAD+
The reduced form of the electron acceptor in glycolysis is _______.
NADH
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?
pyruvate, ATP, and NADH
The ATP that is generated in glycolysis is produced by substrate-level phosphorylation, a very different mechanism than the one used to produce ATP during oxidative phosphorylation. Phosphorylation reactions involve the addition of a phosphate group to another molecule.
Sort the statements into the appropriate bin depending on whether or not they correctly describe some aspect of substrate-level phosphorylation in glycolysis.
-the enzymes involved in ATP synthesis must be attached to a membrane to produce ATP
-an enzyme is required in order for the reaction to occur
-a bond must be broken between an organic molecule and phosphate before ATP can form
-the phosphate group added to make ATP comes from free inorganic phosphate ions
-one of the substrates is a molecule derived from the breakdown of glucose
correct statements- an enzyme is required in order for the reaction to occur, a bond must be broken between an organic molecule and phosphate before ATP can form, one of the substrates is a molecule derived from the breakdown of glucose
incorrect statements- the enzymes involved in ATP synthesis must be attached to a membrane to produce ATP, the phosphate group added to make ATP comes from free inorganic phosphate ions
How many NADH are produced by glycolysis?
2
In glycolysis, ATP molecules are produced by _____.
substrate-level phosphorylation
Which of these is NOT a product of glycolysis?
-FADH2
-NADH
-ATP
-pyruvate
FADH2
In glycolysis, what starts the process of glucose oxidation?
ATP
In glycolysis there is a net gain of _____ ATP.
2
Which of these is an example of negative feedback?
-As a blood clot begins to form, the process of its formation gets faster and faster.
-After you eat, glucagon stimulates an increase in blood sugar levels.
-After you eat, insulin stimulates the lowering of blood sugar levels.
-The digestive enzyme pepsinogen is converted to pepsin by the action of hydrochloric acid; pepsin itself can then convert pepsinogen into pepsin.
-Once labor begins, contractions increase in frequency and intensity.
After you eat, insulin stimulates the lowering of blood sugar levels.
look at diagrams on part 10 of glycolysis, pyruvate processing and...
....
In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction.
Use your knowledge of the first three stages of cellular respiration to determine which explanation is correct.
-More ATP is produced per CO2 released in cyclic processes than in linear processes.
-It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.
-Redox reactions that simultaneously produce CO2 and NADH occur only in cyclic processes.
-Cyclic processes, such as the citric acid cycle, require a different mechanism of ATP synthesis than linear processes, such as glycolysis.
It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA
Which of these enters the citric acid cycle?
-pyruvate
-G3P
-acetyl CoA
-NADH + H+
-glucose
acetyl CoA
In the citric acid cycle, ATP molecules are produced by _____.
substrate-level phosphorylation
Which of these is NOT a product of the citric acid cycle?
-acetyl CoA
-ATP
-NADH + H+
-FADH2
-CO2
acetyl CoA
During aerobic respiration, electrons travel downhill in which sequence?
-food ---> NADH ---> electron transport chain --->oxygen
-food ---> glycolysis ---> citric acid cycle --->NADH--->ATP
-glucose ---> ATP ---> electron transport chain --->NADH
-glucose ---> pyruvate ---> ATP --->oxygen
-food ---> citric acid cycle ---> ATP --->NAD+
food ---> NADH ---> electron transport chain --->oxygen
Where are the proteins of the electron transport chain located?
mitochondrial inner membrane
In cellular respiration the energy for most ATP synthesis is supplied by ____________.
a proton gradient across a membrane
During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
-ATP
-FAD
-NADH
-FADH2
-NAD+
FADH2
The primary role of oxygen in cellular respiration is to _______________ .
-yield energy in the form of ATP as it is passed down the respiratory chain.
-combine with carbon, forming CO2
-catalyze the reactions of glycolysis.
-combine with lactate, forming pyruvate.
-act as an acceptor for electrons and hydrogen, forming water.
act as an acceptor for electrons and hydrogen, forming water
In mitochondrial electron transport, what is the direct role of O2?
-to provide the driving force for the production of a proton gradient
-to provide the driving force for the synthesis of ATP from ADP and Pi
-to function as the final electron acceptor in the electron transport chain
-to oxidize NADH and FADH2 from glycolysis, acetyl CoA formation, and the citric acid cycle
to function as the final electron acceptor in the electron transport chain
How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)
-Electron transport would be unaffected but ATP synthesis would stop.
-Electron transport would stop but ATP synthesis would be unaffected.
-Neither electron transport nor ATP synthesis would be affected.
-Both electron transport and ATP synthesis would stop
Both electron transport and ATP synthesis would stop.
NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule.
Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2?
-Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.
-It takes more energy to make ATP from ADP and Pi using FADH2 than using NADH.
-FADH2 is made only in the citric acid cycle while NADH is made in glycolysis, acetyl CoA formation, and the citric acid cycle.
-The H+ gradient made from electron transport using NADH is located in a different part of the mitochondrion than the H+ gradient made using FADH2.
-There is more NADH than FADH2 made for every glucose that enters cellular respiration.
Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor
Sort into either remains the same, decreases (or goes to zero), or increases depending on the effect that gramicidin would have on each process.
-electron transport rate
-proton pumping rate
- size of the proton gradient
-rate of ATP synthesis
-rate of oxygen uptake
remains the same- proton pumping rate, electron transport rate, rate of oxygen uptake
decreases (or goes to zero)- rate of the ATP synthesis, size of the proton graient
look at diagrams on part 3 of oxidative phosphorylation and chemios...
....
Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops.
Which of these statements is the correct explanation for this observation?
-Oxygen is required to convert glucose to pyruvate in glycolysis. Without oxygen, no pyruvate can be made.
-ATP is needed to convert pyruvate to acetyl CoA. Without oxygen, no ATP can be made in oxidative phosphorylation.
-Oxygen is an input to acetyl CoA formation.
-In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration
In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration
Suppose that a cell's demand for ATP suddenly exceeds its supply of ATP from cellular respiration.
Which statement correctly describes how this increased demand would lead to an increased rate of ATP production?
-ATP levels would fall at first, increasing the inhibition of PFK and increasing the rate of ATP production.
-ATP levels would rise at first, increasing the inhibition of PFK and increasing the rate of ATP production.
-ATP levels would rise at first, decreasing the inhibition of PFK and increasing the rate of ATP production.
-ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production
ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production
During strenuous exercise, anaerobic conditions can result if the cardiovascular system cannot supply oxygen fast enough to meet the demands of muscle cells. Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions.
What would happen to the cell's rate of glucose utilization?
-Glucose utilization would increase a lot.
-Glucose utilization would increase a little.
-Glucose utilization would remain the same.
-Glucose utilization would decrease a little.
-Glucose utilization would decrease a lot.
Glucose utilization would increase a lot
For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle
2
For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle
6
In cellular respiration, most ATP molecules are produced by _____.
oxidative phosphorylation
The final electron acceptor of cellular respiration is _____.
oxygen
During electron transport, energy from _____ is used to pump hydrogen ions into the _____.
NADH and FADH2 ... intermembrane space
look at diagrams in part 4 of oxidative phosphorylation and chemios...
....
The proximate (immediate) source of energy for oxidative phosphorylation is _____
kinetic energy that is released as hydrogen ions diffuse down their concentration gradient
In muscle cells, fermentation produces _____
lactate and NAD+
In fermentation _____ is reduced and _____ is oxidized.
pyruvate ... NADH
Label each product of pyruvate metabolism with which condition it is produced by, either lactate, ethanol, or acetyl CoA.
-aerobic oxidation
-fermentation in human muscle
-fermentation in yeast and bacteria
lactate- fermentation in human muscle
ethanol- fermentation in yeast and bacteria
acetyl CoA- aerobic oxidation
Sort the following items according to whether they are reactants or products in the anaerobic reduction of pyruvate during lactic acid fermentation.
-NAD+
-pyruvate
-NADH
-lactate
reactants- pyruvate, NADH
products- lactate, NAD+
When electrons from NADH are released onto FMN, FMN becomes _____________, and since Fe-S protein is a stronger _________ agent with a ___________ negative Standard Reduction Potential, it immediately accepts the electrons from FMN.
reduced......oxidizing agent......less
As two electrons are passed from FMN to Fe-S proteins, FMN becomes ______________, whereas Fe-S protein becomes __________.
re-oxidized......reduced
If a metaboic poison irreversibly binds to cyt a, cyt a will become permanently ___________, whereas cyt a3 will ber permanently _________.
reduced ...... oxidized
A new mutant has been discovered such that electrons from NADH are not passed to FMN but rather to Cyt b directly. What effect would this change have on the relative magnitude of the electrochemical proton gradient across the inner mitochondrial membrane.
It would reduce the gradient by about 20%
After the first disruption, when electron transfer and ATP synthesis still occur, what must be present?
all of the electron transport proteins as well as ATP synthase
After the further agitation of the membrane vesicles, what must be lost from the membrane?
ATP synthase, in whole or in part
These inside-out vesicles...
-will become alkaline inside the vesicles when NADH is added
-will become acidic inside the vesicles when NADH is added
-will make ATP from ADP and Pi if transfered to a pH4 buffered solution after incubation in a pH 7 buffered solution.
-will hydrolyze ATP to pump protons out of the interior of the vesicle to the exterior.
-will reverse electron flow to generate NADH from NAD+ in the absence of oxygen.
will become acidic inside the vesicles when NADH is added