Exam 4 Problem Roulette Flashcards
Cytochrome c is a mobile electron carrier that moves among Complexes of the mitochondrial electron transport chain. Which Complexes does it move between?
II and IV
II and III
I and III
IV and the F1/Fo ATPase
III and IV
III and IV
Expressing thermogenin (UCP1) generates heat because:
It uncouples Oxygen reduction from proton transport.
It uncouples electron transport from pumping protons, causing the electrons to release their potential energy as heat.
It uncouples proton transport from ATP production, causing the protons to release their potential energy as heat.
None of the options are correct.
It uncouples F1 and Fo causing rapid ATP hydrolysis which releases heat.
It uncouples proton transport from ATP production, causing the protons to release their potential energy as heat.
What is the P/O ratio for mitochondrial oxidation using NADH?
1.5/2/.5
2
3
3/2
2.5
2.5
When the ΔG’° of the ATP synthesis reaction is measured on the surface of the ATP synthase enzyme, it is found to be close to zero. This is thought to be due to:
None of the above
enzyme-induced oxygen exchange.
stabilization of ADP relative to ATP by enzyme binding.
a very low energy of activation.
stabilization of ATP relative to ADP by enzyme binding.
stabilization of ATP relative to ADP by enzyme binding.
Which of the following dehydrogenation reactions do NOT contribute NADH to Complex I?
Malate dehydrogenase
a-ketoglutarate dehydrogenase
Isocitrate dehydrogenase
glutamate dehydrogenase
acyl-CoA dehydrogenase
acyl-CoA dehydrogenase
A new electron carrier has been discovered. It directly passes 4 electrons to ubiqinol. How many ATPs is this carrier worth when fully charged?
1.5 ATPs
3 ATPs
2.5 ATPs
6 ATPs
2 ATPs
3 ATPs
Reactions catalyzed by which of the following proteins do NOT contribute electron carriers to the electron transport chain?
Glucose-6-phosphate dehydrogenase
Malate dehydrogenase
Succinate dehydrogenase
Alcohol dehydrogenase
Glucose-6-phosphate dehydrogenase
What is the final electron acceptor in Oxidative Phosphorylation?
Carbon dioxide
Water
Cytochrome c
Hydrides
Molecular oxygen
Molecular oxygen
Which enzyme passes electrons directly or indirectly to coenzyme Q without pumping protons?
Acyl-CoA dehydrogenase
Glycerol-3-phosphate dehydrogenase
Succinate dehydrogenase
All options are correct
All options are correct
For the following two half reactions:
Cytochrome c (Fe3+) + e– ->cytochrome c (Fe2+) E’ (V) = 0.220
FAD + 2H+ + 2e– -> FADH2 E’ (V) = -0.219
We would expect the spontaneous complete reaction to be:
Cytochrome c (Fe3+) + FADH2 ->cytochrome c (Fe2+) + FAD + 2H+
2 Cytochrome c (Fe3+) + FAD + 2H+ -> 2 cytochrome c (Fe2+) + FADH2
2 Cytochrome c (Fe3+) + FADH2 -> 2 cytochrome c (Fe2+) + FAD + 2H+
Cytochrome c (Fe3+) + FAD + 2H+ -> cytochrome c (Fe2+) + FADH2
2 cytochrome c (Fe2+) + FAD + 2H+ LaTeX: \rightarrow 2 Cytochrome c (Fe3+) + FADH2
2 Cytochrome c (Fe3+) + FADH2 -> 2 cytochrome c (Fe2+) + FAD + 2H+
How many reducing equivalents are transferred to molecular oxygen for the ten protons pumped out of the inner mitochondrial membrane by Complexes I through IV?
10
1
6
2
4
2
Amytal is a barbituate that inhibits Complex I of the electron transport chain. Which of the following might happen if amytal is present in mitochondria:
Increased levels of NADH
ATP is not synthesized
QH2 is not produced
I and II only
II and III only
I, II, and III
I only
II only
I only
In the mitochondria a motive force for ATP/ADP exchange is the __________ and for importing inorganic phosphate into the matrix is the ___________.
membrane potential (positive in the matrix), sodium ion gradient
proton gradient, membrane potential (negative in the matrix)
membrane potential (positive in the matrix), proton gradient
membrane potential (negative in the matrix), sodium ion gradient
membrane potential (negative in the matrix), proton gradient
membrane potential (negative in the matrix), proton gradient
Which of the following electron carriers is lipid soluble?
Cytochrome c
Ubiquinone
Plastocyanin
All of these
Flavin nucleotides
Ubiquinone
About how many protons are passively transported through the F1/Fo complex in order to phosphorylate one molecule of ADP? (Assume 9 c subunits in Fo.)
3.5
4
2
3
2.5
3
The overall reaction: QH2 + 2 cyt c (ox) + 2HN+ -> + 2cyt c (red) + 4HP+ is catalyzed by which electron transfer complex?
ATP synthase
Complex IV
Complex III
Complex I
Complex II
Complex III
There is a defect in Complex III of some mitochondria that prevents protons frombeing pumped to the intermembrane space by this complex. All other complexes apparently function normally. How many total protons are pumped during oxidative phosphorylation in these mutant mitochondria if the initial electrons come from NADH?
2
8
10
6
4
6
In certain tissues, the yield of ATP from _______________ is reduced due to the use of the ___________________ rather than the _________________ for transport of electrons into the respiratory chain.
FADH2, malate-aspartate shuttle, glycerol 3-phosphate shuttle
NADH, malate-aspartate shuttle, glycerol 3-phosphate shuttle
FADH2, glycerol 3-phosphate shuttle, malate-aspartate shuttle
NADH, glycerol 3-phosphate shuttle, malate-aspartate shuttle
NADH, glyceraldehyde-3-phoshate shuttle, malate-aspartate shuttle
NADH, glycerol 3-phosphate shuttle, malate-aspartate shuttle
What is the result of one round of electron transport by Complex I of the Respiratory Chain?
QH2 becomes oxidized
Electrons accepted from NADH are passed to FAD
NADH gets reduced
4 Protons are pumped from the Intermembrane space to the Matrix
4 protons are pumped from the Matrix to the intermembrane space
4 protons are pumped from the Matrix to the intermembrane space
Succinate dehydrogenase is dysfunctional in a species of garden slug. While its metabolism is compromised on a number of levels, it can still undergo oxidative phosphorylation. What is the maximal P/O ratio for these organisms if NADH is used as an electron source?
2.5
4
1
2
1.5
2.5
In ATP synthase, the interaction of stalk with a beta-subunit in the F1 complex contributes to ATP synthesis by:
Decreasing the free energy for formation of a phosphodiester bond between ADP and Pi
Increasing the free energy of ATP dissociation from the beta subunit
Increasing the free energy for protons to cross the membrane
Allowing the c-ring to rotate with a free energy of ~0
Decreasing the free energy of ATP dissociation from the beta subunit
Decreasing the free energy of ATP dissociation from the beta subunit
The following electron carriers are capable of transporting exactly one electron except:
CuA
Cytochrome c
FeS cluster
Ubiquinone
Plastocyanin
Ubiquinone
If an uncoupler is added to the mitochondrial membrane, which of the following would NOT be an expected consequence?
An increase in the electrical potential across the mitochondrial membrane
An increase in oxygen utilization
An increase in temperature
A decrease in the measured P/O ratio
A decrease in the amount of ATP produced per mole of glucose consumed
An increase in the electrical potential across the mitochondrial membrane
Which of the following is an alternative route of entry into the electron transport chain that bypasses both complex I and complex II and transfers electrons directly to ubiquinone?
Malate dehydrogenase
alpha-ketoglutarate dehydrogenase
Succinate dehydrogenase
Glyceraldehyde-3-phosphate dehydrogenase
Glycerol-3-phosphate dehydrogenase
Glycerol-3-phosphate dehydrogenase
Passing two electrons from glycerol-3-phosphate through the respiratory chain yields:
2.5 ATP
None of the other answers is correct
6 ATP
10 ATP
1.5 ATP
1.5 ATP
During oxidative phosphorylation, the proton motive force that is generated by electron transport is used to:
create a pore in the inner mitochondrial membrane.
oxidize NADH to NAD+.
generate the substrates (ADP and Pi) for the ATP synthase.
induce a conformational change in the ATP synthase.
reduce O2 to H2O.
induce a conformational change in the ATP synthase.
What is the result of activation of Complex I of the Respiratory Chain?
4 protons are pumped from the matrix to the intermembrane space
4 Protons are pumped from the intermembrane space to the Matrix
NADH gets reduced
QH2 becomes oxidized
Electrons accepted from NADH are passed to FAD
4 protons are pumped from the matrix to the intermembrane space
Onto which side of the mitochondrial membrane, or into which space, are protons actively pumped during electron transport?
Into the Intermembrane Space
Into the Stroma
Into the Cytoplasm
Into the Lamellae
Into the Lumen
Into the Intermembrane Space
Which of the following is a role for the transmembrane domain of the ATP Synthase at the end of the Respiratory Chain?
Contains the ADP/ATP binding site
Contains the FMN that provides protons for ATP synthesis
Contains the proton pore
Contains the catalytic domain for the ATPase
Contains the electron transport pore
Contains the proton pore
I add an inhibitor of mitochondrial respiration that prevents electron transfer to cytochrome c. Which of the following outcomes is the most likely?
Buildup of QH2 but not NADH; decreased oxygen consumption
Buildup of QH2 but not NADH, increased oxygen consumption
Normal levels of QH2 and NADH; decreased oxygen consumption
Normal levels of QH2 and NADH; increased oxygen consumption
Buildup of both QH2 and NADH; decreased oxygen consumption
Buildup of both QH2 and NADH; decreased oxygen consumption
The following molecules are produced by the first phase of the Q cycle:
Ubiquinol (fully reduced)
Semiquinone radical
Ubiquinone (fully oxidized)
II and III only
I and II only
I only
I, II, and III
I and III only
II and III only
Which of the following is true regarding Ubiquinone?
It is assigned to neither Complex II nor Complex III since its role is to function as a carrier between them
It can accept one electron to become a relatively stable radical
It must accept two protons and 4 electrons to go from a fully reduced to a fully oxidized state.
It contains one FAD and one iron-sulfur center
None of the above statements is true regarding Ubiquinone
It can accept one electron to become a relatively stable radical
How many protons must be pumped across the membrane in order to make 1 molecule of ATP? (Consider all processes. Assume, as we did in class, that the c-ring of Fo has 9 subunits).
10
4
3
2.5
6
4
Fully reduced Electron Transferring Flavoprotein passes its electrons to Coenzyme Q. In what metabolic pathway was ETF reduced by an adenine nucleotide electron carrier?
Glyoxylate Pathway
Pentose Phosphate Pathway
Glycolysis
Kreb’s Cycle
Beta-oxidation of fatty acids
Beta-oxidation of fatty acids
What molecule is central to carbohydrate (i.e. sugar) metabolism in the liver, being at a crossroads of at least 5 important possible fates and whose concentration controls regulatory enzyme activity in each of those fates?
ATP
Glucose 6-phosphate
NADPH
Glutamate
Acetate
Next Question
Glucose 6-phosphate
The active site of the first enzyme in carbon fixation in C3 plants coordinates a magnesium ion. Which amino acid is NOT involved in this coordination?
All of these amino acids coordinate the magnesium.
Asp
Lys
Glu
His
His
The synthesis of amino acids often involves transamination reactions, resulting in the synthesis of which Kreb’s Cycle intermediate?
Fumarate
Citrate
Malate
Oxaloacetate
Alpha-ketoglutarate
Alpha-ketoglutarate
In Photosystem II, which of the following directly oxidizes the Mn4CaO5 cluster?
An exciton
Oxygen (O2)
A tyrosine radical
A special chlorophyll in the P680 reaction center
Water
A tyrosine radical
The Oxygen Evolving Complex produces ____ electrons and pumps ____ H+ into the thylakoid lumen for every O2 produced.
2, 4
8, 8
4, 2
2, 8
4, 4
4, 4
nder times of metabolic stress, what is the correct order of use of BioMolecules in catabolic pathways to ensure enough energy is produced to get through the stress?
Monosaccharides, polysaccharides, triglycerides, amino acids.
Polysaccharides, monosaccharides, triglycerides, amino acids.
Monosaccharides, fatty acids, polysaccharides, amino acids, triglycerides
Fatty acids, monosaccharides, triglycerides, amino acids
Fatty acids, monosaccharides, polysaccharides, amino acids, proteins
Submit
Monosaccharides, polysaccharides, triglycerides, amino acids.
A 30-carbon precursor of the steroid nucleus is:
isopentenyl pyrophosphate.
lysolecithin.
geranyl pyrophosphate.
farnesyl pyrophosphate.
squalene.
squalene
What product from glycogen catabolism in very active skeletal muscle is sent to the liver through the blood as a part of the Cori Cycle?
Lactate (or Lactic Acid)
ATP
NADH
Glucose
Ketone Bodies
Lactate (or Lactic Acid)
If all the Acytyl-CoA used to synthesize a palmitate (C16) fatty acid are in the mitochondria, there will be an additional expense in fatty acid synthesis of up to ________.
16 ATP
7 ATP
2 ATP
14 ATP
8 ATP
16 ATP
he synthesis of Cysteine from Serine requires ___ electrons to reduce sulfate to sulfide.
10
2
8
6
4
8
For the synthesis of one molecule of palmitate, the fatty acid synthase complex (in isolation) consumes the following reagents:
1 acetyl CoA, 7 malonyl CoA, 16 NADPH
8 malonyl CoA, 16 NADPH
8 acetyl CoA, 14 NADPH
8 malonyl CoA, 14 NADPH
1 acetyl CoA, 7 malonyl CoA, 14 NADPH
1 acetyl CoA, 7 malonyl CoA, 14 NADPH
The major pathways of Ammonium Assimilation lead to the synthesis of which one of the following amino acids?
Phosphoenolpyruvate
Asp
Ser
Gln
Gly
Gln
When the [NADPH]/[NADP+] ratio in plants is low, photophosphorylation is primarily non-cyclic. What is/are the major product(s) of photophosphorylation in this circumstance?
I. ATP
II. NADPH
III. O2
II only
I only
I and III
All of these
II and III
II and III
Which prosthetic group is found on all aminotransferases?
Flavin mononucleotide (FMN)
Pyridoxal phosphate (PLP)
Thiamine pyrophosphate (TPP)
Lipoate
Flavin adenine nucleotide (FAD)
Pyridoxal phosphate (PLP)
What structure, molecule or system replenishes the “electron hole” created in the P680 Reaction Center due to exciton transfer?
FADH2
NADH
Ferridoxin
P700
Oxygen evolving complex
Oxygen evolving complex
Malonyl-CoA for acyl chain synthesis is produced by acetyl-CoA carboxylase. What prosthetic group is required for this enzyme?
Transcobalamin
NADH
Biotin
Magnesium
Thiamine pyrophosphate
Biotin
Which one of these is most commonly used as a reducing agent in the cell to facilitate fatty acid synthesis?
NADH
NADPH
NAD+
NADP+
FADH2
NADPH
Which process occurs in photosynthesis?
I. Carbon atoms in CO2 become reduced.
II. Oxygen atoms in water become oxidized.
III. NADP is reduced to NADPH by electron transport processes.
III only
II only
None of these processes occur in photosynthesis.
I, II and III
I only
I, II and III
Which of the following actually leaves a Photochemical Reaction Center, a critical reaction in Photophosphorylation?
A hydride ion
A molecule of oxygen (O2)
A molecule of cytochrome c
An electron
A photon of light
An electron
The strategy of using multiple isozymes to catalyze an early shared step in amino acid synthesis, each of which is subject to a unique set of allosteric effectors is referred to as:
Feedback inhibition
Uncompetitive inhibition
Sequential inhibition
Concerted inhibition
Enzyme multiplicity
Enzyme multiplicity
The difference between C-3 and C-4 plants is
The total number of carbons that are removed as CO2 by one turn of the Calvin Cycle in each plant type
The number of carbons that are in the initial compound into which carbon is fixed
The number of steps in the Calvin Cycle in one type of plant versus the other type of plant
The number of carbons in the final Cycle products of Calvin Cycle for different plants
The number of CO2 molecules required by cells with these pathways to keep the concentration of Oxaloacetate constant in the Kreb’s Cycle
The number of carbons that are in the initial compound into which carbon is fixed
In the mitochondrial shuttles, NADH and acetyl-CoA are carried across the mitochondrial membrane as “equivalents.” NADH is carried across the membrane as _________, and acetyl-CoA is carried across the membrane as _______.
malate; citrate
citrate; malate
malate; pyruvate
citrate; malate
pyruvate; citrat
malate; citrate
The first intermediate in cholesterol synthesis which contains all the carbon atoms which will eventually form the four fused ring cholesterol backbone is
acetyl-CoA
lanosterol
Activated Isoprene
mevalonate
squalene
squalene
The fixation of atmospheric nitrogen is costly with respect to energy, and only certain organisms undergo nitrogen fixation. How many molecules of ATP are required to fix one N2 into 2 NH4+?
32
16
2
8
4
16
The order of the key intermediates in cholesterol synthesis is:
mevalonate, squalene, activated isoprenes, lanosterol
activated isoprenes, mevalonate, squalene, lanosterol
mevalonate, activated isoprenes, lanosterol, squalene
activated isoprenes, mevalonate, lanosterol, squalene
mevalonate, activated isoprenes, squalene, lanosterol
mevalonate, activated isoprenes, squalene, lanosterol
For every CO2 incorporated into 3-phosphoglycerate by Rubisco, ____________ is/are consumed (not counting ribulose 1,5-bisphosphate or water).
1 ATP
no other molecules
1 ATP and 1 NADPH
2 ATP
1 NADPH
no other molecules
You add carbamoyl phosphate with an isotopically-labelled nitrogen to the cell. Which of the following nucleotides will contain the nitrogen label?
GTP
ATP
None of these
CTP
CTP
What important intermediate is the first in the purine synthesis pathway that has a complete double ring structure?
Squalene
Spermidine
Acetolactate
Inosinate
AICAR
Inosinate
In comparing fatty acid biosynthesis with β oxidation of fatty acids, which of the following statements is incorrect?
A thioester derivative of D-β-hydroxybutyrate is an intermediate in the synthetic path, not in the degradative path.
Fatty acid biosynthesis uses NADPH exclusively, whereas β oxidation uses NAD+ exclusively.
The condensation of two moles of acetyl-CoA in the presence of a crude extract is more rapid in bicarbonate buffer than in phosphate buffer at the same pH; the cleavage of acetoacetyl-CoA proceeds equally well in either buffer.
A thioester derivative of crotonic acid (trans-2-butenoic acid) is an intermediate in the synthetic path, but not in the degradative path.
Fatty acid degradation is catalyzed by cytosolic enzymes; fatty acid synthesis by mitochondrial enzymes.
Fatty acid degradation is catalyzed by cytosolic enzymes; fatty acid synthesis by mitochondrial enzymes.
Which of the following is involved in Photophosphorylation and NOT Oxidative Phosphorylation
Coenzyme Q
Iron-Sulfur Centers (Clusters)
Cytochrome B6f
Cytochrome c
Copper Centers
Cytochrome B6f
In the bacterial pheophtyin-quinone reaction centers, how are P870’s electrons replaced?
Oxidation of H2S
From a tyrosine radical
Oxidation of water by the oxygen-evolving complex
They do not have to be replaced because this reaction center is in a cyclic electron transfer pathway.
Oxidation of NADH
They do not have to be replaced because this reaction center is in a cyclic electron transfer pathway.
Heme groups are prosthetic groups in which Complex?
Phosphate translocase
Oxygen Evolving Complex
Complex I
F1/Fo Particles
Complex III
Complex III
In cholesterol synthesis, the first molecule in the synthetic pathway that possesses a sterol nucleus is:
Mevalonate
Squalene
Lanosterol
Cholesterol
Isoprene
Lanosterol
The following enzyme is the most important site of regulation for fatty acid biosynthesis:
Malonyl/Acetyl-CoA-ACP transferase
Enoyl-ACP reductase
Acetyl-CoA carboxylase
Ketoacyl reductase
Ketoacyl synthase
Acetyl-CoA carboxylase
Which of the following statements is NOT true of the major regulatory point for cholesterol synthesis.
I. It is immediately after reactions which are shared with the formation of ketone bodies.
II. It is at a step where 2 NADPH molecules are consumed.
III. A coenzyme A molecule is released.
IV. It introduces a branch point in a linear molecule.
III only
IV only
II only
All of the choices are true.
I only
IV only
Which important intermediate of cholesterol synthesis, beginning with acetate, is itself transformed by three successive phosphoryl group transfer reactions?
Acetoacetyl-CoA
Squalene
Lanosterol
Mevalonate
Isoprenes
Mevalonate
Why are Reaction Centers named as such? (That is, why are they called Reaction Centers?
They capture an exciton of light
They produce carbon dioxide
They produce molecular oxygen
They split water
They release an electron, meaning they participate in oxidation-reduction
They release an electron, meaning they participate in oxidation-reduction
Which of the following is NOT a fate of glucose-6-phosphate in the fed state?
Oxidation via glycolysis, Kreb’s cycle, and the respiratory chain
Dephosphorylation to glucose
Conversion to acetyl CoA for fatty acid synthesis
Synthesis of ribulose-5-phosphate
Conversion to glycogen
Dephosphorylation to glucose
After each round of acyl chain elongation, the new acyl chain moves from
Acetyl CoA to Malonyl CoA
KS to ACP
ACP to Malonyl CoA
ACP to KS
ACP to KS
Which of the following is involved in mitochondrial electron transport and not in electron transport in chloroplasts?
Plastoquinone
Coenzyme Q
Cytochrome c oxidase
Iron-Sulfur Centers (Clusters)
Cytochrome B6/f
Cytochrome c oxidase
Most bacteria can synthesize all twenty amino acids. But certain mutant strains, known as “auxotrophs” are unable to synthesize a particular amino acid, and require the addition of that amino acid to their growth media in order to grow well. A glycine auxotroph would fail to synthesize glycine, as well as the following molecule:
Cytosine Nucleotides
Cysteine
Guanine nucleotides
Serine
3-phosphoglycerate
Guanine nucleotides
Chemical uncouplers of photophosphorylation have been identified. Like mitochondrial uncouplers, these agents cause an increase in temperature of plant tissue. Which of the following is another likely metabolic consequence of a partial uncoupler of photophosphorylation:
Protons move more rapidly from stroma to the thylakoid lumen
Oxygen consumption increases
NADPH synthesis is halted
Via regulatory mechanisms, the plant increases the ratio of cyclic to non-cyclic pathways
Protons accumulate in the thylakoid lumen
Via regulatory mechanisms, the plant increases the ratio of cyclic to non-cyclic pathways
The component of plant reaction centers which is most analogous in function to Complex III in oxidative phosphorylation is:
Cytochrome b6f complex
Ferredoxin:NADP oxidoreductase
Plastocyanin
Cytochrome c2
pheophytin
Cytochrome b6f complex
The following enzyme in the palmitate synthesis pathway is positively regulated by citrate:
Malonyl/Acetyl-CoA-ACP transferase
Acetyl-CoA carboxylase
HMG-CoA reductase
Ketoacyl synthase
Enoyl-ACP reductase
Acetyl-CoA carboxylase
CMP, UMP, and TMP all have _____ as a common precursor.
glutamine
adenosine
aspartate
S-adenosyl methionine
inosine
aspartate
Which of the following statements is/are correct about purine synthesis?
I. GTP is required for the synthesis of AMP.
II. ATP is required for the synthesis of AMP.
III. GTP is required for the synthesis of GMP.
IV. ATP is required for the synthesis of GMP.
I and IV
II and IV
I only
II only
III only
IV only
I and IV
Which of the following chemical transformations regulates Rubisco?
Phosphorylation/dephosphorylation
Reduction/Oxidation
Decarboxylation
Carbamoylation
Protonation
Carbamoylation
Carbamoyl phosphate is an important intermediate in the synthesis of which of the following groups of molecules?
Pyrimidines
Amino acids derived from Pyruvate
Deoxyribonucleotides
Aromatic amino acids
Purines
Pyrimidines
In photosynthesis, absorption of light energy in chloroplast “light reactions” ultimately leads to:
absorption of O2 and release of CO2.
absorption of CO2 and release of O2.
hydrolysis of ATP and reduction of NADP+.
use of iron-sulfur proteins.
synthesis of ATP and oxidation of NADPH.
absorption of CO2 and release of O2.
Which of the following molecules in photophosphorylation is NOT an integral membrane protein?
Plastocyanin
Light Harvesting Complex
Photosystem II
Photosystem I
Cytochrome b6f complex
Plastocyanin
Glutamine synthetase converts _____ to _____ whereas glutamate synthase converts ____ to _____.
α-ketoglutarate; glutamine; α-ketoglutarate; glutamate
asparagine; glutamine; α-ketoglutarate; glutamate
glutamate; glutamine; α-ketoglutarate; glutamate
formate; glutamine; ammonia; glutamate
α-ketoglutarate; glutamine; oxaloacetic acid; glutamate
glutamate; glutamine; α-ketoglutarate; glutamate
What is the important intermediate at a branch point that leads to either AMP or GMP synthesis?
Folate
Xanthylate
AICAR
Chorismate
Inosinate
Inosinate
What molecule is the ultimate electron donor in Photophosphorylation?
NADH
Chlorophyll
Water
Oxygen
Carbon Dioxide
Water
Identify which of the following is not present in chloroplasts but is present in mitochondria
Iron-Sulfur centers (clusters)
Matrix
Porphyrin rings
DNA
Electron transport system
Matrix
Which of the following molecules are negative regulators of fatty acid synthesis?
Citrate
Epinephrine
Palmityl-CoA
III only
I only
None of these
I and II only
II and III only
II and III only
ukaryotic cells synthesize which of the following from CDP-diacylglycerol?
Sucrose
Glycerol
Cholesterol
Starch
Phospholipids
Phospholipids
What amino acid serves as a reactant in most transamination reactions for amino acid synthesis?
Ala
Gly
Arg
Glu
Gln
Glu
Which of the following terms describes leptin?
Steroid hormone
Autocrine hormone
Endocrine hormone
Paracrine hormone
Eicosanoid hormone
Endocrine Hormone
Which of the following important intermediates of cholesterol synthesis is missing from this list taken from the four summary steps: Acetate, Squalene, Cholesterol?
Phosphatidic Acid
Malonyl-CoA
Mevalonate
Methyl-malonyl-CoA
CDP-choline
Mevalonate
The cellular respiration rate is regulated by ADP. This is an example of which regulatory mechanism?
Mass action
Feedback regulation
Acceptor control
Concerted regulation
Sequential Inhibition
Acceptor control
Identify the correct order of the four biochemical mechanisms that are repeated many times to produce Palmitate from Acetyl-CoA and Malonyl-CoA
Reduction, Dehydration, Reduction, Condensation
Condensation, Reduction, Reduction, Dehydration
Reduction, Condensation, Reduction, Dehydration
Dehydration, Reduction, Condensation, Reduction
Condensation, Reduction, Dehydration, Reduction
Condensation, Reduction, Dehydration, Reduction
One amino acid directly involved in the purine biosynthetic pathway is:
tryptophan
glutamate.
alanine.
leucine.
aspartate
aspartate
Which of the following is NOT required for the synthesis of Cholesterol from its initial precursor?
Coenzyme A
Carbon dioxide
NADPH
ATP
Carbon dioxide
Which of the following would NOT supply NADPH (from NADP+) that could be used for anabolic pathways?
Pentose Phosphate Pathway
Malic Enzyme
Photosynthesis
All of the above produce NADPH
Beta-Oxidation
Beta-Oxidation
Which of the following is true of non-cyclic phosphorylation in photosynthesis?
NADH donates electrons to reduce P680, causing phosphorylation of ADP
Molecular oxygen is evolved and NADP+ is reduced
The same electrons used by the oxygen evolving complex are not used for ADP phosphorylation.
ADP phosphorylated by Cfo/CF1 is transported from chloroplasts and not used by them, so there is no phosphorylation/dephosphorylation cycle
Activated electrons from NADP+ reduction are passed through Plastocyanin to reduce P700+
Molecular oxygen is evolved and NADP+ is reduced
Which of the following nucleic acid derivatives is used in large amounts for fatty acyl chain synthesis?
NADH
FMN
NADP+
NADPH
ACP
NADPH
Which of the following is the proper order of electron transport between Photosystem II and Photosystem I in higher plant membranes?
Cytochrome Q, Cytochrome a, Cytochrome c
Plastocyanin, plastoquinone, iron-sulfur center
Chlorophyll a, plastocyanin, plastoquinone
Pheophytin, plastocyanin, plastoquinone
Plastoquinone, Cytochrome b6/f, plastocyanin
Plastoquinone, Cytochrome b6/f, plastocyanin
Fatty acid synthesis requires _____________ for each round, while beta oxidation yields _______________ for each round.
NADPH; FADH2
1 FADH2 and 1 NADH; 2 NADH
2 NADH; 1 FADH2 and 1 NADPH
2 NADPH; 1 FADH2 and 1 NADH
NADPH; NADH
2 NADPH; 1 FADH2 and 1 NADH
ome herbicides inhibit electron transfer to plastocyanin. Which of the following is a likely effect of this herbicide?
Excessive heat is generated, causing enzyme denaturation
ATP synthesis and NADPH synthesis are both prevented
ATP synthesis continues, but NADPH is not formed
The oxygen-evolving complex cannot donate electrons to Photosystem II
NADPH synthesis continues, but ATP is not formed
ATP synthesis continues, but NADPH is not formed
Electrons in photosystem I come from _____; electrons in photosystem II come from _____.
Photosystem II; O2
O2; Photosystem I
NADPH, Photosystem 1
H2O; Photosystem I
Photosystem II; H2O
Photosystem II; H2O
Where in the chloroplast is Plastocyanin located?
On the cytoplasmic side of the chloroplast
On the Inside of the outer membrane
On the stromal side of the membranes
On the lumenal side of the stromal membranes
On the outside of the outer membrane
On the lumenal side of the stromal membranes
Which of the following characterizes C4 plants?
High photorespiration rate, high metabolic rates, high water loss
Low starch concentration in leaf cells, low light conditions, wet and humid environment
Low water loss, growth in high light/tropical conditions, high photosynthetic rates
High water loss, high photosynthetic rates, high metabolic rates
Low water loss, growth in high light/tropical conditions, high photosynthetic rates
The key regulatory step in cholesterol biosynthesis is catalyzed by:
Mevalonate 5-phosphotransferase
Phosphomevalonate kinase
HMG-CoA reductase
Acetyl CoA carboxylase
HMG-CoA synthase
HMG-CoA reductase
What prosthetic group is required by acetyl-CoA carboxylase, covalently linked to a Lys residue?
Vitamin B12
Tetrahydrofolate
FADH2
Biotin
Cardiolipin
Biotin
What is the form of sulfur that is incorporated into Cys (using Serine)?
Sulfate
Sulfide
Sulfite
H2S
Sulfide
An amino acid that does not derive its carbon skeleton, at least in part, from α-ketoglutarate is:
threonine.
glutamine.
proline.
glutamate.
arginine.
threonine
When the [NADPH]/[NADP+] ratio in plants is high, photophosphorylation is primarily cyclic. What is/are the major product(s) of photophosphorylation in this circumstance?
ATP + NADPH
NADPH
O2
ATP
ATP
Which of the following statements describes insulin?
A “bottom-up” metabolic regulator that signals that blood glucose is low
A peptide hormone that signals that blood glucose is low
A “top-down” metabolic regulator that leads to a decrease in blood glucose levels
A “bottom-up” metabolic regulator that leads to a decrease in blood glucose levels
A “top-down” metabolic regulator that leads to an increase in blood glucose levels
A “bottom-up” metabolic regulator that leads to a decrease in blood glucose levels
What is the main regulatory mechanism on Purine Synthesis?
Phosphorylation/dephosphorylation of the first enzyme of the pathway
Feedback inhibition, mostly by monophosphates
Limitation of the starting reactant, which comes from Glycolysis
Competitive inhibition by Pyrimidine diphosphates
Inhibition of the formation of AICAR
Feedback inhibition, mostly by monophosphates
The molecule exported from the mitochondria to feed into fatty acid synthesis also regulates ___________and ______________.
carnitine acyltransferase and acetyl-CoA carboxylase
Fatty acid synthase and acetyl-CoA carboxylase
Fatty acid synthase and PFK-1
PFK-1 and carnitine acyltransferase
PFK-1 and acetyl-CoA carboxylase
PFK-1 and acetyl-CoA carboxylase
The cellular ATP/ADP ratio controls the rate of:
Oxidative phosphorylation
The TCA cycle
Glycolysis
I only
II and III
I and II
I, II and III
I and III
I, II and III
During the initial charging step of fatty synthesis, a(n) ________ group is covalently linked to a _________ of acyl carrier protein.
Malonyl; cysteine
Acetyl; biotin prosthetic group
Acetyl; cysteine
Acetyl; phosphopantetheine prosthetic group
Malonyl; phosphopantetheine prosthetic group
Malonyl; biotin prosthetic group
Malonyl; phosphopantetheine prosthetic group
Which of the following enzymes is present in the Calvin cycle, but not present in either glycolysis or the pentose phosphate pathway?
Transketolase
Transaldolase
Aldolase
Phosphoglycerate kinase
Ribulose 5-phosphate kinase
Ribulose 5-phosphate kinase
Inosinate (IMP) serves as a precursor in pathways that generate which of the following?
Thymidine
NADH
Fumarate
Asp
Cytosine
Fumarate
Which of the following statements best describes the reactions of the Third Stage of Carbon Assimilation?
Decarboxylation of pentose phosphates to produce oxaloacetate
Triose phosphates are reduced to form glyceraldehyde 3-phosphate
Dihydroxyacetone phosphate is used to produce either starch or sucrose
Triose phosphates are converted to pentose phosphates
Carbon dioxide is incorporated into a pentose
Submit
Triose phosphates are converted to pentose phosphates
The synthesis of DNA requires deoxyribonucleotides derived from ribonucleotides by reduction. What molecule provides the reducing equivalents for this reaction?
NADPH
NADH
FADH2
NAD+
NADP+
NADPH
How many malonyl-CoA and acetyl-CoA are necessary to produce 1 molecule of Palmitate?
1 Malonyl-CoA and 7 Acetyl-CoA
1 Malonyl CoA and 8 Acetyl-CoA
1 Malonyl-CoA and 8 Acetyl-CoA
7 Malonyl-CoA and 1 Acetyl-CoA
7 Malonyl-CoA and 7 Acetyl-CoA
7 Malonyl-CoA and 1 Acetyl-CoA
Coenzyme Q and cholesterol synthesis share which common precursor?
Squalene
NADH
Activated Isoprene
Malonyl-CoA
Lanosterol
Activated Isoprene
Which pair of amino acids would you expect to have essentially identical synthesis pathways (parallel reactions, same chemistry), differing only by the identity of one of the starting substrates?
Trp, Tyr
Val, Ile
Asp, Gln
Ser, Cys
Thr, Ser
Val, Ile
Cholesterol is synthesized from:
choline.
malate.
acetyl-CoA.
oxalate.
lipoic acid.
acetyl-CoA.
Pyrimidine nucleotides are synthesized de novo from what amino acid and using what extra source of energy?
Asn and NADPH
Ser and ATP
Glu and NADH
Asp and GTP
Asp and ATP
Asp and ATP
Which of the following does NOT describe a physiological consequence of high blood glucagon levels?
Inhibition of acetyl-CoA carboxylase
Glucose released to the blood
Incorrect
Decreased activity of phosphofructokinase in the liver
Polymerization of fatty acid synthetase
Increased activity of glycogen phosphorylase
Polymerization of fatty acid synthetase
For which group of molecules below is Inosinate (IMP) an important intermediate?
Pyrimidine nucleotides
Amino acids derived from alpha-ketoglutarate
Purine nucleotides
Amino Acids derived from 3-phosphoglycerate
the deoxyribonucleic acids
Purine nucleotides
From the choices below, select the one which is NOT shared between oxidative phosphorylation and photophosphorylation
participation of quinones.
chlorophyll.
proton pumping across a membrane to create electrochemical potential.
use of iron-sulfur proteins.
involvement of cytochromes.
chlorophyll.
On which side of the chloroplast membrane is the ATP Synthase active site?
On the stromal side of the membranes
On the Inside of the outer membrane
On the outside of the outer membrane
On the cytoplasmic side
On the lumenal side of the stromal membranes
On the stromal side of the membranes
If all the electrons used in the reductive steps of the synthesis of a palmitate (C16) fatty acid were instead fed into the respiratory chain for ATP synthesis, there could be a net production of up to _______ ATP.
40
28
17.5
35
20
35
The Oxygen Evolving Complex of Photophosphorylation
Accepts electrons and produces molecular oxygen, plus pumps 4 protons to the thylakoid lumen
Passes 4 electrons to P700+
Links PSII with PSI through a pair of Cytochrome molecules
Passes 4 electrons to P680+ and passes 4 protons to the chlorplast stroma
Incorrect
Uses a Manganese Complex rather than Magnesium to remove electrons from molecular oxygen
Accepts electrons and produces molecular oxygen, plus pumps 4 protons to the thylakoid lumen
Place the following electron-carriers into the proper order as found in plant chloroplasts.
1) Cytochrome b6f complex
2) Plastocyanin
3) P700
4) P680
5) NADPH
4, 1, 2, 3, 5
1, 3, 4, 2, 5
2, 1, 3, 4, 5
4, 2, 5, 1, 3
3, 2, 4, 1, 5
4, 1, 2, 3, 5
Many plants synthesize several different photopigments. With respect to photophosphorylation, the reason for this is:
If the reactants to synthesize chlorophyll are not available, other photopigments can replace chlorophyll in the photosystems
This provides several alternate routes of electron entry to the photosystems
Photopigments with different absorption maxima can absorb photons from the entire visible spectrum
The different standard reduction potentials of different photopigments allow them to operate under a variety of different redox conditions
Plants synthesize different photopigments depending on the nutrients available
Photopigments with different absorption maxima can absorb photons from the entire visible spectrum
The compartment of the chloroplast which is analogous to the intermembrane space of the mitochondria is:
thylakoid lumen
outer membrane
granal stacks
thylakoid membrane
stroma
thylakoid lumen
Head-group Exchange is a strategy used for the synthesis of
Palmitate
Triacylglycerols
Cholesterol
Membrane phospholipids
Leukotrienes
Membrane phospholipids
The initial reaction in the REDUCTIVE phase (Stage 2) of the Calvin cycle is the reverse of a particular reaction in another pathway. What is the driving force for this reaction in the Calvin cycle?
In the direction it runs in the Calvin cycle, there is a large and negative LaTeX: \DeltaΔ
G’0 so the reaction is naturally favorable.
This reaction is favorable due to the high concentration of NADPH made in the light reactions of photosynthesis.
This reaction uses Mg2+ and the elevated concentration of Mg2+ during the day helps to drive it forward
This reaction is favorable due to the high concentration of ATP made in the light reactions of photosynthesis.
This reaction is favorable due to the high concentration of ATP made in the light reactions of photosynthesis.
The final reaction in synthesizing dNTPs is catalyzed by ribonucleotide reductase. This enzyme will:
Catalyze the hydrolysis of the 2’OH from an NTP.
Reduce the 2’ OH on an NTP using 2 electrons
Oxidize the 3’ OH on an NTP releasing 2 electrons
Oxidize the 3’ OH on an NTP releasing 2 electrons
Reduce the 3’ OH on an NTP using 2 electrons
Reduce the 2’ OH on an NTP using 2 electrons
