Cell Structure and Function Test 2
Pyruvate dehydrogenase is regulated by all of the following except NADH. CO2. acetyl CoA. AMP. ATP.
CO2.
The ER and Golgi work together to package and glycosylate proteins for secretion, incorporation into the plasma membrane, or deposition in other organelles of the endomembrane system. If a researcher were to add a nonhydrolyzable analog of GTP (cannot be hydrolyzed to GDP) intracellularly, which of the following processes would most likely be impacted? oligosaccharide synthesis on glycoproteins in the ER and Golgi COPI- and COPII-dependent transport between the ER and Golgi clathrin-uncoating of vesicles vesicular fusion for exocytosis at the plasma membrane
COPI- and COPII-dependent transport between the ER and Golgi
What is the role of calcium at the synaptic terminal? What is the role of calcium at the synaptic terminal? Calcium, like sodium, is out of both ionic and electrical equilibrium. Therefore, it counteracts the loss of free energy following depolarization of the synaptic terminal. Depolarization of the synaptic terminals by an invading action potential opens voltage-gated calcium channels at the terminal, thus permitting diffusion of calcium out of the synaptic terminal. Depolarization of the synaptic terminals by an invading action potential releases intracellular calcium stores or allows calcium channels to open to allow calcium to enter the synaptic terminal from the extracellular environment, thus permitting neurotransmitter release. Calcium enters the synaptic terminal, permitting water to enter, increasing hydrostatic pressure, and forcing neurotransmitter out of the terminal into the synapse.
Depolarization of the synaptic terminals by an invading action potential releases intracellular calcium stores or allows calcium channels to open to allow calcium to enter the synaptic terminal from the extracellular environment, thus permitting neurotransmitter release.
IP3 receptors are associated with mitochondrial membranes. ER membranes. intracellular membranes. lysosomes. plasma membranes.
ER membranes.
Which of the following statements about action potentials is false? Electrical signals are propagated along a dendrite. Due to leaking, membranes are subject to subthreshold depolarization, which is insufficient to produce the action potential. A refractory period is always necessary following an action potential. They require rapid changes in membrane potential. At the end of the action potential, most neurons show a transient hyperpolarization.
Electrical signals are propagated along a dendrite.
Pyruvate is the end-product of glycolysis. Many organisms, such as anaerobic bacteria, can only produce energy by glycolysis; therefore, pyruvate has no more potential for ATP generation for these organisms. Rather than simply excrete pyruvate, this molecule is changed to another molecule such as lactate. In these organisms, why is pyruvate changed to lactate and excreted, rather than simply excreted? Pyruvate export requires more energy than lactate. Electrons (and protons) are added to pyruvate to make lactate. NAD+ is regenerated as pyruvate is changed to lactate. Substrate level phosphorylation changes pyruvate to lactate. Electrons (and protons) are added to pyruvate to make lactate and NAD+ is regenerated as pyruvate is changed to lactate.
Electrons (and protons) are added to pyruvate to make lactate and NAD+ is regenerated as pyruvate is changed to lactate.
The number of ATPs per NADH generated by the electron transport system is higher than the number generated per FADH2 because __________. electrons from FADH2 are not oxidized all the way to water FADH2 has a higher (more negative) redox potential than NADH does FADH2 has a lower (less negative) redox potential than NADH does NADH is converted to NAD+, which increases the charge gradient for ATP synthesis
FADH2 has a lower (less negative) redox potential than NADH does
Which of the following would be most consistent with mammalian cells in culture that are primarily using glycolysis to make ATP and have a ratio of NADH/NAD+ that is higher than normal? Ethanol is being converted back to pyruvate. ATP is being depleted rapidly. ADP is being phosphorylated to ATP too quickly. Lactate dehydrogenase is being inhibited under anaerobic conditions.
Lactate dehydrogenase is being inhibited under anaerobic conditions.
Which of the following statements best describes the role of NAD+/NADH in glycolysis? NADH is used to produce energy by directly creating the phosphoanhydride bonds in ATP. NADH is capable of pumping ions during glycolysis. NADH is used primarily in substrate-level phosphorylation. NAD+ is used to carry electrons. all of the above
NAD+ is used to carry electrons.
During strenuous exercise, you may notice that your muscles burn. Which of the following statements best explains this phenomenon? Carbon dioxide is building up in muscle and changing the pH. Without oxygen, pyruvate is being converted to lactic acid. Pyruvic acid causes muscle pain. Proteins are being digested to provide energy. ADP is accumulating, which produces a burning sensation.
Without oxygen, pyruvate is being converted to lactic acid.
Which of the following is not a product of the TCA cycle? ATP FADH2 acetyl CoA CO2 NADH
acetyl CoA
Kinases are enzymes that remove phosphate groups. add phosphate groups. do not alter target activity. are always inhibitory. all of the above
add phosphate groups.
Which of the following experimental strategies could be used to block the IP3 branch but not the DAG branch of the IP3 pathway? inhibition of phospholipase C addition of a cAMP phosphodiesterase inhibitor adding an antagonist of the IP3 receptor inhibition of protein kinase C
adding an antagonist of the IP3 receptor
Which term best describes the nitrogenous base adenine plus the sugar ribose? adenosine diphosphate adenine adenosine triphosphate adenosine adenosine diphosphate followed by adenine or adenosine
adenosine
Which of the following pairings is not correct? phospholipase C-diacylglycerol (DAG) adenylyl cyclase-ATP phospholipase C-inositol triphosphate calmodulin-calcium ions
adenylyl cyclase-ATP
In an experiment, mice were fed glucose containing a radioactive carbon atom at position 1. This atom was found in __________. early TCA intermediates only, then carbon dioxide coenzyme A NADH all TCA intermediates, then carbon dioxide
all TCA intermediates, then carbon dioxide
Cyclic AMP is __________. an allosteric regulator of adenylyl cyclase an allosteric regulator of phospholipase C an allosteric regulator of protein kinase A an allosteric regulator of phosphodiesterase
an allosteric regulator of protein kinase A
Because NADH generated in the cytosol cannot enter the mitochondrion, electrons and protons from NADH are transferred in by __________. a proton pump an electron shuttle system lactate cytochromes
an electron shuttle system
Synthetic compounds that inhibit receptors by preventing the natural messenger from binding are known as antagonists. syndecans. receptor upregulators. specific proteoglycans. agonists.
antagonists.
Which of the following would induce synaptic release of neurotransmitter in the absence of an action potential in a neuron? Which of the following would induce synaptic release of neurotransmitter in the absence of an action potential in a neuron? inhibition of neurotransmitter receptors in the dendrites of the axons increasing the rate of neurotransmitter removal from the synaptic cleft demyelination of the axon application of a calcium ionophore that equilibrated calcium between the cytoplasm of the synaptic terminal and the extracellular space
application of a calcium ionophore that equilibrated calcium between the cytoplasm of the synaptic terminal and the extracellular space
The portion of the nervous system that is associated with the control of involuntary activities is the peripheral nervous system. autonomic nervous system. somatic nervous system. automatic nervous system. central nervous system.
autonomic nervous system.
In electron transport, which respiratory complex is not involved in the flow of electrons from FADH2? complex I complex II complex III complex IV all of the above
complex I
Of the following sequences, which shows the correct molecules through which electrons flow when delivered to the electron transport system by NADH? complex I, coenzyme Q, complex III, complex IV, oxygen complex II, coenzyme Q, complex III, complex IV, oxygen complex I, cytochrome c, complex III, coenzyme Q, complex IV, oxygen complex I, coenzyme Q, complex III, cytochrome c, complex IV, oxygen complex I, coenzyme Q, complex IV, cytochrome c, oxygen
complex I, coenzyme Q, complex III, cytochrome c, complex IV, oxygen
In electron transport, which respiratory complex is not involved in the flow of electrons from NADH? complex I complex II complex III complex IV all of the above
complex II
Proton gradients are generated by all of the following complexes except complex III. complex II. complex IV. coenzyme Q. complex I.
complex II.
Hyperpolarization of the postsynaptic nerve terminal does not affect the initiation of an action potential. decreases the chance that an action potential will be initiated. increases the chance that an action potential will be initiated. is stimulated by an influx of calcium ions. none of the above
decreases the chance that an action potential will be initiated.
Oxidation in biological systems is usually accompanied by hydrogenation. resonance stabilization. repulsion. dehydrogenation. all of the above
dehydrogenation.
Desensitization of a cell to a ligand may involve all of the following except a lessened response to the ligand. lowered affinity of a receptor for the ligand. receptor-mediated endocytosis. destruction of the ligand. receptor down-regulation.
destruction of the ligand.
To have a hormone receptor system that is responsive to changes in hormone concentration, it is useful if the concentration of the hormone is far below the Kd before the stimulation of hormone secretion. always more than 10 times the Kd. never more than 10 times the Kd. far above the Kd before the stimulation of hormone secretion. always constant.
far below the Kd before the stimulation of hormone secretion.
The form of fatty acid that is transported into the mitochondrion is decarboxylated fatty acid residues. triacylglycerols. fatty acyl CoA phospholipids. sulfated fatty acid
fatty acyl CoA
You add a large amount of XFF to cultured liver cells. Which of the following might you observe if XFF can bind to human epinephrine receptors? glucose-6-phosphate polymerization decreased protein synthesis increased cell division glycogen breakdown all of the above
glycogen breakdown
A phosphoanhydride bond Check all that apply. has a standard free energy of hydrolysis of -7.3 kcal/mol. is a high-energy bond. is broken by hydrolysis.
has a standard free energy of hydrolysis of -7.3 kcal/mol. is a high-energy bond. is broken by hydrolysis.
In eukaryotes, pyruvate is converted to acetyl CoA when passing the mitochondrial cristae. in the mitochondrial matrix. in the cellular cytosol. when passing through the mitochondrial outer membrane. in the intermembrane space.
in the mitochondrial matrix.
Electron transport and oxidative phosphorylation are metabolic functions of the __________ of the mitochondrion. matrix inner membrane outer membrane intermembrane space
inner membrane
All of the following are glial cells except astrocytes. interneurons. oligodendrocytes. Schwann cells. interneurons and Schwann cells.
interneurons.
MAPKs are activated by microtubules. membranes. mitogens. methylation. methionine.
mitogens.
An action potential can always be initiated specifically at which of the following locations associated with a neuron? synaptic boutons nodes of Ranvier ion channels ion channels and synaptic boutons none of the above
nodes of Ranvier
As pyruvate is prepared for the TCA cycle, it undergoes a process of reductive decarboxylation. oxidative decarboxylation. oxidative carboxylation. reductive carboxylation. CoQ reproduction.
oxidative decarboxylation.
If a eukaryotic organism does not depend on fatty acids as an energy source, one would expect to find β-oxidation activity associated with which of the following organelles? peroxisome ribosome cytoplasm mitochondrion cell membrane
peroxisome
It would be useful to determine if the mechanism of action for the XFF-XFF receptor is similar to that of estrogen or epinephrine. To test this, you use a nonhydrolyzable analogue of GTP in the reaction mixture. If the mechanism is still similar to that of epinephrine, you would expect the cellular responses would be blocked. prolonged. delayed. prolonged and delayed. The mechanism cannot be determined.
prolonged.
Which hormone is not an amino acid derivative? thyroxine epinephrine histamine norepinephrine prostaglandin
prostaglandin
Which of the following is not a final electron acceptor in anaerobic respiration? iron nitrate sulfur pyruvate hydrogen
pyruvate
Pyruvate is converted to acetyl CoA by a unique enzyme known as multiplex enzyme system. transitionase system. pyruvate decarboxylase. pyruvate CoA transferase. pyruvate dehydrogenase complex.
pyruvate dehydrogenase complex.
The purpose of the fermentation process is the production of novel compounds, such as inorganic acids. generation of additional energy in the form of ATP. generation of additional reducing equivalents. regeneration of NAD+. all of the above
regeneration of NAD+.
Phosphatases are enzymes that remove phosphate groups. do not alter target activity. are always inhibitory. add phosphate groups. all of the above
remove phosphate groups.
All of the following are directly used as alternative substrates for glycolysis except mannose. fructose. galactose. ribose. galactose and ribose.
ribose.
The somatic nervous system controls cardiac muscle. some glands. smooth muscle. skeletal muscles. the brain and spinal cord.
skeletal muscles.
Both the phosphorylation of intermediates and the formation of ATP in glycolysis are examples of substrate-level phosphorylation. anabolic phosphorylation. oxidative phosphorylation. product-level phosphorylation. aerobic phosphorylation.
substrate-level phosphorylation.
Which of the following is not a product of fermentation? sucrose ethanol lactate CO2 NAD+
sucrose
Statins are drugs that are administered to inhibit the biosynthesis of cholesterol in the liver, and thus are used to lower blood plasma cholesterol levels in order to decrease patient risk of atherosclerosis and associated diseases such as myocardial infarction (heart attack). Which of the following components of the endomembrane system is the site of action of statin drugs? the nucleus lysosomes the ER the Golgi complex
the ER
Which of the following would NOT necessarily affect the rate of cellular respiration and oxidative phosphorylation? the availability of reduced coenzymes the availability of ADP an intact inner mitochondrial membrane the availability of fatty acids
the availability of fatty acids
Much of the suitability of ATP as an energy intermediary is related to the instability of the bonds between the phosphate groups. These bonds are unstable because __________. the valence electrons in the phosphorus atom have less energy on average than those of other atoms the negatively charged phosphate groups vigorously repel one another they are hydrogen bonds, which are only about 10% as strong as covalent bonds the phosphate groups are polar and are attracted to the water in the interior of a cell
the negatively charged phosphate groups vigorously repel one another
Alpha- and beta-adrenergic receptors can bind epinephrine and norepinephrine, yet they trigger different signal transduction pathways. This is because __________. only one of the receptors is phosphorylated each receptor is a different tyrosine kinase only one of the receptors is activated by calcium the receptors activate different G proteins
the receptors activate different G proteins
In brown fat, ________ present in the inner mitochondrial membrane uncouples ATP synthesis from electron transport in infants and other newborn mammals. fluorocitrate thermogenin respirasomes coenzyme A submitochondrial particles
thermogenin
When one pyruvate is oxidized, the products created specifically by the TCA cycle are __________. oxygen, ATP, NAD+, and FAD two carbon dioxide, one ATP, three NADH, and one FADH2 oxygen, ATP, NADH, and FADH2 three carbon dioxide, one ATP, four NADH, and one FADH2
two carbon dioxide, one ATP, three NADH, and one FADH2
Vytorin is a relatively new drug used to treat hypercholesterolemia, and it actually contains two active, efficacious ingredients. Vytorin contains a statin drug that inhibits a crucial enzyme in cholesterol biosynthesis, but it also contains a compound that inhibits the intestinal absorption of cholesterol from the diet. Which of the following is an accurate assessment of whether this drug can or cannot be used to treat familial hypercholesterolemia (FH)? Vytorin cannot be used to treat FH patients, because it is targeting the missing enzyme for cholesterol biosynthesis in FH patients. Vytorin can be used to treat FH patients, because it is not targeting the missing enzyme for cholesterol biosynthesis in FH patients. Vytorin cannot be used to treat FH patients, because it is targeting the missing receptor in FH patients. Vytorin can be used to treat FH patients, because it is not targeting the missing receptor in FH patients.
vytorin can be used to treat FH patients, because it is not targeting the missing receptor in FH patients.
In the electron transport system, hydrogen atoms removed from NADH ultimately end up as part of __________. carbon dioxide NADH water ATP
water
The sequential process of fatty acid catabolism to acetyl CoA is called the glyoxylate cycle. β-oxidation. oxidative phosphorylation. the Cori cycle. hydrogenation.
β-oxidation.
The resting potential of a particular nerve cell is -66 mV. Depolarization of the membrane will shift the membrane potential toward -90 mV. 0 mV. -66 mV. There will be no change. There is not enough information to tell.
0 mV.
Which answer shows the correct order of occurrence during an action potential? Which answer shows the correct order of occurrence during an action potential? 1.resting state, hyperpolarizing phase, depolarizing phase, repolarizing phase 2.resting state, depolarizing phase, repolarizing phase, hyperpolarizing phase 3.depolarizing phase, hyperpolarizing phase, repolarizing phase, resting state 4.hyperpolarizing phase, depolarizing phase, repolarizing phase, resting state
2.resting state, depolarizing phase, repolarizing phase, hyperpolarizing phase
The gross output of ATP from glycolysis is ________, whereas the net output of ATP is ________. 6; 4 4; 2 2; 1 4; 1 2; 4
4; 2
The overall efficiency of aerobic respiration in eukaryotes is about 10%. 25%. 55%. 75%. 100%.
55%.
Which of the following events marks the transition to the uncoating phase for clathrin-coated vesicles? calcium release from the endoplasmic reticulum the binding of v-SNAREs to t-SNAREs ATP hydrolysis a lowering of pH
ATP hydrolysis
Choose the correct explanation of why this is so. At least some of the sodium channels in the membrane will open in response to a stimulus that depolarizes the membrane by about 20 mV. At least some of the potassium channels in the membrane will open in response to a stimulus that depolarizes the membrane by about 20 mV. Most of the sodium channels in the membrane will close in response to a stimulus that depolarizes the membrane by about 20 mV.
At least some of the sodium channels in the membrane will open in response to a stimulus that depolarizes the membrane by about 20 mV.
A researcher generates a mutant cell line in a laboratory culture in which the mutants have an RGS-GAP that is increased in activity. What is the likely outcome of this mutation? G protein-mediated cellular signaling will terminate faster. G protein-mediated cellular signaling will be prolonged. Smooth muscle relaxation will be initiated and prolonged. Adenylyl cyclase activity will increase.
G protein-mediated cellular signaling will terminate faster
Glucose is transported in the bloodstream to cells in all parts of your body. In cells, glucose has four main fates. Which of the following is not one of those fates? Glucose is transformed into sucrose. Glucose is converted to lactate. Glucose is used to synthesize glycogen. Glucose is catabolized to carbon dioxide and water. Glucose is converted to acetyl CoA to make body fat.
Glucose is transformed into sucrose.
The gene for the glycolytic enzyme hexokinase is genetically altered so that it contains an SH2 domain at the C-terminus and then is expressed in yeast cells. Which of the following is the most likely outcome of this experiment? Hexokinase will bind to and interact with activated receptor tyrosine kinases. Hexokinase will bind to and interact with phospholipase C. Hexokinase will bind to and interact with albumin. Hexokinase will bind to and interact with Ras.
Hexokinase will bind to and interact with activated receptor tyrosine kinases.
Pyruvate dehydrogenase is allosterically inhibited by ATP. Consider the picture in part A. High ATP levels indicate low levels of NAD+, so it is reasonable to shut down the reaction that consumes it. High ATP levels indicate adequate energy supply, so it makes sense that the enzyme responsible for providing the TCA cycle with more ATP is shut down. High ATP levels indicate adequate energy supply, so it makes sense that the enzyme responsible for providing the TCA cycle with more acetyl CoA substrate is shut down. High ATP levels indicate low levels of CoA−SH, so it is reasonable to shut down the reaction that consumes it.
High ATP levels indicate adequate energy supply, so it makes sense that the enzyme responsible for providing the TCA cycle with more acetyl CoA substrate is shut down.
Biosynthesis of insulin It is associated with smooth endoplasmic reticulum. It is associated with Golgi. It is associated with peroxisomes. It is associated with rough endoplasmic reticulum and Golgi. It is associated with peroxisomes and mitochondria. It is associated with endoplasmic reticulum. It is associated with mitochondria. It is associated with lysosome.
It is associated with rough endoplasmic reticulum and Golgi.
The dehydrogenases that oxidize isocitrate, α-ketoglutarate, and malate (reactions TCA-3, TCA-4, and TCA-8) are all allosterically inhibited by NADH. Consider the picture in part A. High NADH levels indicate high pH of the mitochondrial matrix, so it makes sense to shut down the metabolic pathway responsible for the formation of more H+ ions. High NADH levels indicate low pH of the mitochondrial matrix, so it makes sense to shut down the metabolic pathway responsible for the formation of more H+ ions. High NADH levels mean adequate oxidized coenzyme for the generation of more ATP, so it makes sense to shut down the catabolic machinery of the cell. High NADH levels mean adequate reduced coenzyme for the generation of more ATP, so it makes sense to shut down the catabolic machinery of the cell.
High NADH levels mean adequate reduced coenzyme for the generation of more ATP, so it makes sense to shut down the catabolic machinery of the cell.
Phosphofructokinase (Reaction Gly-3) is allosterically inhibited by citrate. High citrate levels are indicative of a sufficient supply of acetyl CoA, so it is reasonable that the key regulatory enzyme of the pathway leading to pyruvate and acetyl CoA is decreased in activity. High citrate levels are indicative of a sufficient supply of isocitrate, so it is reasonable that the key regulatory enzyme of the pathway leading to isocitrate is decreased in activity. High citrate levels are indicative of a sufficient supply of oxaloacetate, so it is reasonable that the key regulatory enzyme of the pathway leading to oxaloacetate is decreased in activity. High citrate levels are indicative of a insufficient supply of acetyl CoA, so it is reasonable that the key regulatory enzyme of the pathway leading to pyruvate and acetyl CoA is increased in activity.
High citrate levels are indicative of a sufficient supply of acetyl CoA, so it is reasonable that the key regulatory enzyme of the pathway leading to pyruvate and acetyl CoA is decreased in activity.
Isocitrate dehydrogenase (Reaction TCA-3) is allosterically activated by ADP. High levels of ADP mean high levels of ATP, so it is to the advantage of the cell to activate the metabolic pathway responsible for coenzyme oxidation, which can in turn give rise to ATP synthesis by electron transport. High levels of ADP mean high levels of ATP, so it is to the advantage of the cell to activate the metabolic pathway responsible for coenzyme reduction, which can in turn give rise to ATP synthesis by electron transport. High levels of ADP mean low levels of ATP, so it is to the advantage of the cell to activate the metabolic pathway responsible for coenzyme reduction, which can in turn give rise to ATP synthesis by electron transport. High levels of ADP mean low levels of ATP, so it is to the advantage of the cell to activate the metabolic pathway responsible for coenzyme oxidation, which can in turn give rise to ATP synthesis by electron transport.
High levels of ADP mean low levels of ATP, so it is to the advantage of the cell to activate the metabolic pathway responsible for coenzyme reduction, which can in turn give rise to ATP synthesis by electron transport.
Pyruvate dehydrogenase kinase is allosterically activated by NADH. High levels of NADH mean adequate reduced coenzyme for the generation of ATP, so it makes sense to convert PDH to the active (phosphorylated) form, which is what PDH kinase does. High levels of NADH mean adequate oxidized coenzyme for the generation of ATP, so it makes sense to convert PDH to the inactive (phosphorylated) form, which is what PDH kinase does. High levels of NADH mean adequate reduced coenzyme for the generation of ATP, so it makes sense to convert PDH to the inactive (phosphorylated) form, which is what PDH kinase does. High levels of NADH mean adequate oxidized coenzyme for the generation of ATP, so it makes sense to convert PDH to the active (phosphorylated) form, which is what PDH kinase does.
High levels of NADH mean adequate reduced coenzyme for the generation of ATP, so it makes sense to convert PDH to the inactive (phosphorylated) form, which is what PDH kinase does.
α-ketoglutarate dehydrogenase (Reaction TCA-4) is allosterically inhibited by succinyl CoA. Consider the picture in part A. High levels of succinyl CoA signal adequate levels of TCA-cycle intermediates, so it seems reasonable to shut down further TCA cycle activity. High levels of succinyl CoA signal adequate levels of NADH, so it seems reasonable to shut down the anabolic machinery of the cell. High levels of succinyl CoA signal adequate levels of α-ketoglutarate, so it is reasonable to decrease in activity an enzyme that is responsible for formation of α-ketoglutarate. High levels of succinyl CoA signal low levels of CoA−SH, so it seems reasonable to shut down the reaction that consumes it.
High levels of succinyl CoA signal adequate levels of TCA-cycle intermediates, so it seems reasonable to shut down further TCA cycle activity.
Biosynthesis of cholesterol It is associated with peroxisomes and mitochondria. It is associated with smooth endoplasmic reticulum. It is associated with mitochondria. It is associated with peroxisomes. It is associated with Golgi. It is associated with lysosome.
It is associated with smooth endoplasmic reticulum.
If every neuron exhibits an all-or-none response, how do you suppose the nervous system of an animal can distinguish different intensities of stimulation? How do you think your own nervous system can tell the difference between a warm iron and a hot iron or between a chamber orchestra and a rock band? Select all that apply: Intensity of stimulus is detected as the changes in membrane voltage. Intensity of stimulus is detected as the frequency with which individual neurons respond. Intensity of stimulus is detected as the difference in the number of separate neurons that respond. Intensity of stimulus is detected as the changes in concentration of calcium.
Intensity of stimulus is detected as the frequency with which individual neurons respond. Intensity of stimulus is detected as the difference in the number of separate neurons that respond.
β oxidation of long-chain fatty acids It is associated with Golgi. It is associated with lysosome. It is associated with mitochondria. It is associated with peroxisomes and mitochondria. It is associated with rough endoplasmic reticulum and Golgi. It is associated with peroxisomes. It is associated with smooth endoplasmic reticulum. It is associated with endoplasmic reticulum.
It is associated with peroxisomes and mitochondria.
The chemiosmotic model of ATP synthesis is based on several lines of experimental evidence. Which of the following statements is not correct experimental evidence to support the chemiosmotic model? Oxidative phosphorylation does not require a membrane-enclosed compartment. Electron transport causes protons to be pumped out of the mitochondrial matrix. Uncoupling agents abolish both the proton gradient and ATP synthesis. Artificial proton gradients established by addition of acid can drive ATP synthesis in the absence of electron transport. The proton gradient established by electron transport has enough energy to drive ATP synthesis.
Oxidative phosphorylation does not require a membrane-enclosed compartment.
Which of the following accurately summarizes the substrate-level phosphorylation strategy of ATP synthesis in glycolysis? Electrons and hydrogen atoms are transferred to NAD+, which then transfers a phosphate to ADP to make ATP. Phosphate groups are transferred exergonically from high-energy phosphorylated intermediates to ADP to make ATP. Electrons are transported through a series of carriers to reduce substrates and drive the phosphorylation of ADP to ATP. Energy from the sun is used to create a proton gradient that is used by an ATP synthase to phosphorylate ADP to ATP.
Phosphate groups are transferred exergonically from high-energy phosphorylated intermediates to ADP to make ATP.
Which of the following statements is false with regard to G-protein coupled receptors (GPCRs)? Adenylate cyclase is activated. Phosphodiesterase creates v cAMP molecules in response to moderate cAMP levels. Protein Kinase A is activated by cAMP. GPCRs can interact with specific receptor interacting proteins to modify ligand affinity. cAMP signals for its own degradation indirectly.
Phosphodiesterase creates v cAMP molecules in response to moderate cAMP levels.
__________ results from the rapid summation of __________ over time, bringing the postsynaptic neuron to its threshold. __________ occurs at the postsynaptic neuron when multiple action potentials from several presynaptic neurons result in a large depolarization by the postsynaptic neuron. Spatial summation; IPSPs; Synaptic inhibition Spatial summation; EPSPs; Temporal summation Temporal summation; EPSPs; Spatial summation Temporal summation; IPSPs; Spatial summation
Temporal summation; EPSPs; Spatial summation
A particular interneuron is designed to receive a stimulus from other neurons in the form of the neurotransmitter GABA. Which of the following is an accurate description of the dendrites of this interneuron? A particular interneuron is designed to receive a stimulus from other neurons in the form of the neurotransmitter GABA. Which of the following is an accurate description of the dendrites of this interneuron? The dendrites will be heavily insulated with myelin. The dendrites will compose the white matter of this interneuron. The dendrites of this interneuron will release GABA. The dendrites of this interneuron will contain large quantities of GABA receptors.
The dendrites of this interneuron will contain large quantities of GABA receptors.
Which of the following statements regarding the Ras protein is false? Ras activates a cascade of phosphorylation events. It is regulated by GTPase activating proteins. It is regulated by Sos, a guanine nucleotide exchange factor. The ligands are largely steroid hormones. Ras is monomeric.
The ligands are largely steroid hormones.
With respect to an action potential, which of these statements is the most relevant regarding its direction of propagation? With respect to an action potential, which of these statements is the most relevant regarding its direction of propagation? Dendrites contain a high density of sensitive voltage-gated sodium channels that initiate an action potential. The neuronal voltage-sodium channel has a refractory period following activation. The myelin sheath prevents charge leakage, allowing the current to move in only one direction. The membrane potential change generated by influx of ions propels the action potential until the Na+/K+ pump can restore balance.
The neuronal voltage-sodium channel has a refractory period following activation.
A patient was diagnosed to possess a mutation in an ER-resident protein in which the ER-signal sequences of the protein were inappropriately deleted and instead replaced with a mannose-6-phosphate during protein synthesis and posttranslational modification. What is the likely fate of this mutant protein? The protein would not be glycosylated. The protein never enters the Golgi complex. The protein would be targeted to the lysosomes. The protein would be secreted by exocytosis.
The protein would be targeted to the lysosomes.
Why are mitochondria so prevalent in skeletal muscle? They are needed to provide energy for muscle contraction. They are needed to repair damaged tissue that accumulates during exercise. They give the muscle enough elasticity to contract. Bones and muscles require a great deal of energy to prevent them from separating. The flow of blood is greatest in skeletal muscle.
They are needed to provide energy for muscle contraction.
In the first step of glycolysis, glucose can be phosphorylated because a phosphoanhydride bond has higher energy of hydrolysis than a phosphoester bond. the transfer of a phosphate from ATP to glucose is exergonic. both the number 2 and 3 carbons can be spontaneously phosphorylated. the ketosugar is rapidly phosphorylated at the carbon 1 hydroxyl group. a phosphoanhydride bond has higher energy of hydrolysis than a phosphoester bond and the transfer of a phosphate from ATP to glucose is exergonic.
a phosphoanhydride bond has higher energy of hydrolysis than a phosphoester bond and the transfer of a phosphate from ATP to glucose is exergonic.
The mannose-6-phosphate receptor would have what type of protein tag? a KDEL ER retention tag a cis-Golgi retention tag a lysosomal targeting tag a trans-Golgi retention tag
a trans-Golgi retention tag
In comparing beta -oxidation to glycolysis, it can be said that __________. beta-oxidation produces more energy per carbon because all carbons go through the TCA cycle, whereas only two-thirds of carbons from glucose do both occur in the cytosol beta-oxidation bypasses acetyl co-A beta-oxidation releases carbon dioxide and glycolysis does not
beta-oxidation produces more energy per carbon because all carbons go through the TCA cycle, whereas only two-thirds of carbons from glucose do
The axon branches of a typical neuron terminate at structures called boutons. synapses. myelin sheath. nodes of Ranvier. glia.
boutons.
Of the following electron carriers of the electron transport system, which transfers protons in addition to electrons? iron-sulfur proteins iron-copper proteins coenzyme Q cytochrome a cytochrome b
coenzyme Q
The stimulus for secretion of neurotransmitters into the synaptic cleft is an increase in calcium levels. chloride levels. potassium levels. sodium levels. neurotransmitter levels.
calcium levels.
In the Golgi complex, __________. the anterograde transport system is used to move vesicles back to the ER proteins are synthesized proteins are N-glycosylated carbohydrate side chains of glycoproteins are modified
carbohydrate side chains of glycoproteins are modified
The breakdown of glucose to pyruvate by a cell is an example of a(n) ________ reaction. aerobic amphibolic anabolic synthesis catabolic
catabolic
An energy-liberating pathway is considered to be metabolic. catabolic. hydrogenation. anabolic. all of the above
catabolic.
A researcher is attempting to isolate rough ER microsomes using ultracentrifugation. Which of the following would indicate contamination of the rough ER with another organelle? membranes ribosomes glycosylated proteins catalase
catalase
Calcium ionophores __________. inhibit calcium ATPases and allow cytosolic calcium to increase bind with calmodulin and mimic the effect of calcium or IP3 cause membranes to become permeable to calcium, allowing entry to the cytosol from ER and extracellular stores and mimicking the effect of IP3 inhibit ryanodine receptor channels and decrease the effect of IP3
cause membranes to become permeable to calcium, allowing entry to the cytosol from ER and extracellular stores and mimicking the effect of IP3
Which of the following ligands would not have an intracellular receptor? retinoic acid thyroxine progesterone epinephrine cortisol
epinephrine
All of the following are second messengers, except cyclic adenosine monophosphate. calcium ions. inositol trisphosphate. epinephrine. diacylglycerol.
epinephrine.
Which of the following represents a "molecular switch" that activates Gα proteins? the binding of ATP exchange of GDP for GTP on Gα GTP hydrolysis exchange of GTP for GDP on Gα
exchange of GDP for GTP on Gα