Midterm 3

Cyanide is very toxic in high enough doses because it binds irreversibly to cytochrome C. Which of the following is not an effect of cyanide's inhibition of cytochrome C? a) Increase in the rate of the citric acid cycle's activity b) Increased ratio of ADP:ATP c) Build-up of NADH d) Increased pH in the mitochondrial intermembrane space

a) Increase in the rate of the citric acid cycle's activity

Which of the hypothesis for insulin resistance was derived from excess fat deposition in adipocytes? a) Inflammation b) Lipid overload c) Atherosclerotic d) Altered signaling

a) Inflammation

In mammalian cells, where is the ATP synthase protein complex located? a) Inner membrane of mitochondria b) Outer membrane of mitochondria c) Cytoplasmic membrane d) Mitochondrial matrix

a) Inner membrane of mitochondria

Britten and Kane found that when DNA was first cut into segments of 300 base pairs and then heated to cause strand separation, almost half of the DNA reassociated very quickly. Which of the following statements from this experiment are correct? 1. Sequence reassociation was a consequence of relatively high abundance. 2. Sequences that reassociated quickly were present as multiple copies. 3. The sequences that did not reassociate were silent genes. 4. The slowly associating sequences require an additive to anneal. a) Only statements 1 and 2 are true. b) Only statements 1 and 3 are true. c) All of the listed statements are true. d) None of the listed statements are true.

a) Only statements 1 and 2 are true.

Which of the following is the ETC mobile electron carrier that is soluble in the inner membrane? a) QH2 b) FMN c) Cytochrome c d) Cytochrome c1

a) QH2

Where are proteins mainly stored to be used as a fuel reserve? a) Skeletal muscle b) Liver c) Adipocytes d) Lungs

a) Skeletal muscle

Which of these processes in aerobic respiration would not be possible in the absence of oxygen? a) The electron transport chain b) Formation of NADH from NAD+ c) Substrate-level phosphorylation d) The Citric acid cycle

a) The electron transport chain

What is the main problem when digesting, absorbing, and transporting lipids? a) Their insolubility in aqueous environments. b) Their hydrophilic in aqueous environments. c) Their size in aqueous environments. d) Their interactions with other fats in aqueous environments.

a) Their insolubility in aqueous environments.

What is NOT true about hormones? a) They act directly on target enzymes. b) They bind to cell receptors. c) Not all enzymes require second messenger. d) The hormones belong to chemical class of peptides, steroids and amino acids derivatives.

a) They act directly on target enzymes.

At which point do the electrons of FADH2 enter the electron transport chain? a) Complex IV b) Complex II c) Complex I d) Complex III

b) Complex II

Which of the following hormones promote food intake? a) insulin and leptin b) insulin and glucocorticoids c) ghrelin and adiponectin d) adrenaline and aldosterone

c) ghrelin and adiponectin

How many total ATP molecules can be generated for each FADH2, assuming oxidative phosphorylation is 100 percent efficient? a) 3.3 b) 3 c) 2.5 d) 2

d) 2

How many carbon atoms do each of the following molecules contain? (1) citrate (2) alpha-ketoglutarate (3) OAA (4) Acetyl group on CoA a) 6, 6, 5, 2 b) 6, 5, 5, 3 c) 7, 6, 4, 3 d) 6, 5, 4, 2

d) 6, 5, 4, 2

Which of the following statements about the generation of ATP in the electron transport chain is correct? a) The generation of ATP from ADP coupled to electron transfer occurs by substrate level phosphorylation as in glycolysis. b) Electron transport generates a proton gradient across the outer mitochondrial membrane. c) ATP synthase generation of ATP involves a rotating structure outside the inner mitochondrial membrane. d) ATP synthase generation of ATP involves a rotating structure inside the inner mitochondrial membrane.

d) ATP synthase generation of ATP involves a rotating structure inside the inner mitochondrial membrane.

A-ketoglutarate dehydrogenase is regulated by which of the following? a) Allosteric inhibition b) Allosteric activation c) Product inhibition d) All are correct answers

d) All are correct answers

Of the choices below, which is the LEAST oxidized molecule? a) Succinate b) Malate c) Oxaloacetate d) Citrate

d) Citrate

At which point do electrons of NADH enter the electron transport chain? a) Complex III b) Complex II c) Complex IV d) Complex I

d) Complex I

What enzyme catalyzes the reaction of oxygen to form water? a) NADH-Q oxidoreductase b) Q-cytochrome c oxidoreductase c) NADH dehydrogenase d) Cytochrome c oxidase

d) Cytochrome c oxidase

Which of the following functions is NOT carried out by the liver? a) Gluconeogenesis b) Plasma protein synthesis c) Cholesterol synthesis d) Generation of ATP for mechanical work

d) Generation of ATP for mechanical work

Eukaryotic DNA is packaged very differently than bacterial DNA. Which of the following statements is true of eukaryotic DNA packaging? a) It requires proteins that are mostly acidic in nature. b) The most abundant protein associated with packaged DNA is chromatin. c) The proteins known as histones are exclusively responsible for gene expression. d) It is packaged with special proteins known as histones.

d) It is packaged with special proteins known as histones.

After prolonged starvation the source of energy to brain is mainly derived from ________. a) Muscle protein b) Fatty acid c) Cholesterol d) Ketone bodies

d) Ketone bodies

When the beta-subunit interacts with the gamma-subunit of ATP Synthase, it can exist in the following conformational state(s): a) Open b) Tight c) Loose d) all of the above

d) all of the above

The reactions of the citric acid cycle occur in the _____________ . a) mitochondrial intermembrane space b) cytoplasm c) mitochondrial inner membrane d) mitochondrial matrix

d) mitochondrial matrix

In cellular respiration, most ATP molecules are produced by _____. a) substrate-level phosphorylation b) photophosphorylation c) cellular respiration d) oxidative phosphorylation e) photosynthesis

d) oxidative phosphorylation

Oxidative phosphorylation refers to __________. a) the electron transport chain coupled to glycolysis b) the citric acid cycle coupled to ATP synthesis c) beta-oxidation coupled to ATP synthesis d) the electron transport chain coupled to ATP synthesis

d) the electron transport chain coupled to ATP synthesis

How many total ATP molecules can be generated for each NADH, assuming oxidative phosphorylation is 100 percent efficient? a) 3.3 b) 3 c) 2.5 d) 2

a) 3.3

How many electrons enter Complex I from the complete oxidation of pyruvate? a) 8 b) 6 c) 4 d) 2 e) 0

a) 8

How many cycles of beta-oxidation are required to metabolize a 20:0 acyl-CoA? a) 9 b) 8 c) 10 d) 11

a) 9

Isocitrate dehydrogenase is down-regulated by which method? a) Allosteric inhibition b) Post-translational modification via phosphorylation c) Feedback activation d) None of these

a) Allosteric inhibition

Which enzyme in the citric acid cycle is responsible for catalyzing the rate-limiting step? a) Alpha-ketoglutarate dehydrogenase b) Isocitrate dehydrogenase c) Citrate synthase d) Malate dehydrogenase

a) Alpha-ketoglutarate dehydrogenase

Which ATP synthase subunit binds protons from the intermembrane space? a) C10 b) Beta c) Alpha d) Gamma

a) C10

The chromosomes are present in nucleus as an entangled mass of DNA-protein complex called ________. a) Chromatin b) Chromonema c) Chromoplasm d) Chromatid

a) Chromatin

Which set of lipoprotein particles is ordered from largest to smallest by size? a) Chylomicron > VLDL > LDL > HDL b) HDL > LDL > VLDL > chylomicron c) Chylomicron > VLDL > HDL > LDL d) VLDL > chylomicron > HDL > LDL

a) Chylomicron > VLDL > LDL > HDL

Coenzyme Q carries electrons between which stages of the electron-transport chain? a) Complex I, II and III only b) Complex III and Complex IV only c) Complex I and II only d) Complex I and III only

a) Complex I, II and III only

Which of the following is NOT a two-electron carrier? a) Cytochrome c b) QH2 c) FADH2 d) NADH

a) Cytochrome c

Why is there variability with regards to ATP production via oxidative phosphorylation? a) Depends on the shuttle system used by NADH. b) Depends on the shuttle system used by FADH2. c) Depends on where in the cell ATP production takes place. d) Depends on how much ATP is produced during Glycolysis and the Citric Acid Cycle.

a) Depends on the shuttle system used by NADH.

What determines the sequence of electron carriers in the electron transport chain? a) Electrons are passed through the complexes in order of increasing reduction potential. b) Electrons are passed through the complexes in order of decreasing reduction potential. c) Electrons are passed through the complexes randomly. d) Electrons are passed through the complexes in a manner that decreases entropy.

a) Electrons are passed through the complexes in order of increasing reduction potential.

In resting muscles, which compound is used an energy source? a) Fatty acid b) Glucose c) Ketone bodies d) Lactic acid

a) Fatty acid

Which enzyme from the liver helps in maintaining the blood sugar level? a) Hexokinase IV b) Glucokinase c) Phosphokinase d) Phosphatase

a) Hexokinase IV b) Glucokinase

What reaction is catalyzed by lipoprotein lipase, or lipase? a) Hydrolysis of TAGs into fatty acids and glycerol. b) Hydrolysis of cholesterol into acetyl-CoA. c) Hydrolysis of TAGs into amino acids and glycerol. d) Hydrolysis of cholesterol into fatty acid and water.

a) Hydrolysis of TAGs into fatty acids and glycerol.

What is the main mechanism of action for oxidative phosphorylation? a) Uses the free energy of the proton gradient generated as a result of transferring electrons from NADH or FADH2 to O2 by a series of electron carriers for ATP production. b) Uses the net yield of ATP produced by Glycolysis and the Citric Acid Cycle to produce more ATP. c) Uses the free energy released during redox reactions in Complexes I-IV (the electron transport chain) and is uncoupled to Complex V (ATP synthase). d) To make more ATP from outside sources such as extracellular proteins.

a) Uses the free energy of the proton gradient generated as a result of transferring electrons from NADH or FADH2 to O2 by a series of electron carriers for ATP production.

Multicellular organisms are dependent on _____________________ to switch from a quiescent to proliferative state for normal growth. a) growth factors b) nutrients c) biomass d) glycolysis

a) growth factors

Water-soluble hormones affect target cells by binding to __________. a) plasma membrane receptors b) cAMP c) adenylate cyclase d) protein kinases

a) plasma membrane receptors

The enzyme pyruvate dehydrogenase generates _____ acetyl CoA, _______ NADH, and _____ CO2 molecule. a) 2, 1, 1 b) 1, 1, 1 c) 1, 2, 1 d) 1, 2, 2

b) 1, 1, 1

Which ATP synthase subunit catalyzes the phosphorylation of ADP? a) Alpha b) Beta c) Gamma d) C10

b) Beta

What is the mechanism of action for the Citrate Synthase 2-part reaction? a) Hydrolysis followed by condensation b) Condensation followed by hydrolysis c) Decarboxylation followed by hydrolysis d) Decarboxylation followed by condensation

b) Condensation followed by hydrolysis

Which of these are a characteristic of diabetes mellitus? a) Excess of ketones in urine b) Excess of glucose in urine c) Excess of amino acids in urine d) Excess of fatty acids in urine

b) Excess of glucose in urine

Where is the hormone binding site on a transmembrane receptor? a) Cytosol b) Extracellular c) Inner layer of plasma membrane d) Nuclear lamina

b) Extracellular

How do endocrine hormones reach their target cells? a) Hormones are released at synapses adjacent to target cells. b) Hormones are transported through the blood stream to target cells. c) Hormones are produced by endocrine cells that are adjacent to target cells. d) Ducts transport hormones directly to target cells.

b) Hormones are transported through the blood stream to target cells.

In mammalian cells, where does the electron transport chain take place? a) Outer membrane of mitochondria b) Inner membrane of mitochondria c) Cytoplasmic membrane d) Mitochondrial matrix e) Mitochondrial intermembrane space

b) Inner membrane of mitochondria

Cytochrome c, an essential protein of the electron transport chain, is located in the mitochondria. Please identify its specific location. a) Matrix b) Intermembrane space c) Inner membrane d) Outer membrane

b) Intermembrane space

Which of the following is not an example of substrate-level phosphorylation? a) 1, 3-Bisphosphoglycerate -----> 3-Phosphoglycerate b) Isocitrate ----> alpha-ketoglutarate c) Phosphenolpyruvate ----> Pyruvate d) SuccinylcoA ----> Succinate

b) Isocitrate ----> alpha-ketoglutarate

What alternate fuel reserve is used by brain during starving conditions? a) Acetyl-CoA b) Ketone bodies c) Malonyl-CoA d) HMG-CoA reductase

b) Ketone bodies

Why does the brain require large amounts of ATP for its functions? a) Mechanical work b) Membrane potential to transmit nerve impulse c) Blood circulation d) Ultrafiltration

b) Membrane potential to transmit nerve impulse

During the electron transport, energy from ________ is used to pump hydrogen ions into the ________. a) acetyl CoA; intermembrane space b) NADH and FADH2 ; intermembrane space c) NADH and FADH2 ; mitochondrial matrix d) NADH; mitochondrial matrix e) NADH; intermembrane space

b) NADH and FADH2 ; intermembrane space

The first reaction of the citric acid cycle, where acetyl-CoA and __________ combine to form citrate, is catalyzed by __________. a) CoA; isocitrate dehydrogenase b) OAA; citrate synthase c) isocitrate; citrate synthase d) OAA; alpha-ketoglutarate dehydrogenase

b) OAA; citrate synthase

What is the purpose of the proton motive force? a) Powers the phosphorylation of ATP to ADP. b) Powers the phosphorylation of ADP to ATP. c) Powers the production of high energy electron carriers. d) Powers the ability to generate more redox reactions.

b) Powers the phosphorylation of ADP to ATP.

Which of the following statements about the generation of ATP in the electron transport chains is correct? a) The F1 subunit of the ATP synthase contains the motor which is driven to rotate by the proton flow. b) The F1 subunit of the ATP synthase contains the catalytic center that synthesizes ATP. c) The F0 subunit of the ATP synthase binds ADP and Pi tightly before ATP synthesis occurs. d) The F0 subunit of the ATP synthase contains the catalytic center that synthesizes ATP.

b) The F1 subunit of the ATP synthase contains the catalytic center that synthesizes ATP.

What is oxidized in each round of beta-oxidation? a) The carbonyl carbon of the acyl chain b) The beta carbon of the acyl chain c) NAD+ d) FAD

b) The beta carbon of the acyl chain

Which of the following statements about the electron transport chain is correct? a) The electron transport chain is made up of a chain of electron carriers with decreasing electron affinity. b) The electron transport chain is made up of a chain of electron carriers with increasing redox potential. c) The electron transport chain is made up of a chain of electron carriers with decreasing oxidizing power. d) The electrons transferred from carrier to carrier in the electron transport chain gain energy.

b) The electron transport chain is made up of a chain of electron carriers with increasing redox potential.

Which statement is TRUE about the H2A, H2B, H3 and H4 histone proteins? a) They are not present in equimolar concentration. b) They are present in equimolar concentration. c) They are present as a tetramer. d) They are present as a hexamer with two units each of H3 and H4.

b) They are present in equimolar concentration.

Most of the oxygen that we take in by breathing is converted to __________. a) carbon dioxide b) water c) neither water nor carbon dioxide d) hydrogen peroxide

b) water

A deficiency in which of the following within the mitochondrial matrix will not limit a cell's rate of oxidative phosphorylation? a) O2 b) NAD+ c) A deficiency in any of these will limit the rate of oxidative phosphorylation d) FADH2

c) A deficiency in any of these will limit the rate of oxidative phosphorylation

Which of the following is the least dense, with the highest ratio of lipid to proteins? a) VLDL b) IDL c) Chylomicrons d) HDL

c) Chylomicrons

Carbon atoms enter the citric acid cycle in the reaction involving which enzyme? a) Malate dehydrogenase b) Isocitrate dehydrogenase c) Citrate synthase d) Alpha-ketoglutarate dehydrogenase

c) Citrate synthase

In mammalian cells, where does the electron transport chain take place? a) Outer membrane of mitochondria b) Cytoplasmic membrane c) Inner membrane of mitochondria d) Mitochondrial matrix

c) Inner membrane of mitochondria

Which of the following components are NOT part of a major fuel reserve in the body? a) Glycogen b) Protein c) Insulin d) Triacylglycerols

c) Insulin

Does the citric acid cycle directly require oxygen (O2)? a) Yes, oxygen is required to reduce NAD+ to NADH in the citric acid cycle. b) No, carbon dioxide is the only gas that is a substrate for the citric acid cycle. c) No, oxygen (O2) is not a substrate for any of the enzyme-catalyzed reactions. d) Yes, the citric acid cycle requires oxygen (O2) to make ATP.

c) No, oxygen (O2) is not a substrate for any of the enzyme-catalyzed reactions.

The chromosomes are held in nucleus by ________. a) Nuclear membrane b) Nuclear sheath c) Nuclear envelope d) Nuclear lamina

c) Nuclear envelope

Which of the following is not a major fuel reserve in the human body? a) Triacylglycerols b) Protein c) Nucleic acids d) Glycogen

c) Nucleic acids

What is the role of activated protein kinases? a) Degrade cAMP to AMP. b) Phosphorylate ADP to ATP. c) Phosphorylate proteins. d) Activate adenylate cyclase

c) Phosphorylate proteins.

Why are citrate synthase, isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase good candidates for regulation of the citric acid cycle? a) These enzymes are feedback inhibited by high [ATP]. b) These enzymes control the output of the pathway by keeping [intermediates] high. c) These enzymes catalyze the irreversible reactions in the citric acid cycle. d) These enzymes are allosterically activated by high [ATP].

c) These enzymes catalyze the irreversible reactions in the citric acid cycle.

Aconitase catalyzes a reaction in which Citrate is converted to D-Isocitrate. What is the purpose of this reaction? a) To cause the release of water. b) To free CO2 from the reaction. c) To relocate the hydroxyl group so a carbonyl group can later be formed. d) To produce a high energy electron carrier.

c) To relocate the hydroxyl group so a carbonyl group can later be formed.

The chemiosmotic theory states that: a) mitochondrial enzymes will pump protons to the cytosol to create a proton motive force. b) protons only get pumped into the mitochondrial matrix. c) free energy is used to pump protons of the mitochondrial matrix into the intermembrane space. d) none of the above

c) free energy is used to pump protons of the mitochondrial matrix into the intermembrane space.

The heme prosthetic groups that are present within cytochromes can each accept how many electrons at a time? a) 1 b) 2 c) 3 d) none

a) 1

How many electrons enter Complex II from complete oxidation of pyruvate? a) 4 b) 6 c) 8 d) 0 e) 2

e) 2

Imagine that a toxin is introduced to the body and inhibits the establishment of the proton gradient in the intermembrane space. What would you predict would be the result? a) NADH would be oxidized b) Fermentation could not occur c) Substrate-level phosphorylation would be inhibited d) Pyruvate would be unable to enter the Citric acid cycle e) ATP synthase would be unable to produce ATP

e) ATP synthase would be unable to produce ATP

What is reduced in each round of beta-oxidation? a) The beta carbon of the acyl chain b) The carbonyl carbon of the acyl chain c) FAD d) NAD+ e) NAD+ and FAD

e) NAD+ and FAD

The heart has the largest metabolic demand of any organ. Which of the following is not a primary substrate of the heart metabolism for ATP production? a) Glucose b) Fatty acids c) ketone bodies d) Lactate e) Protein

e) Protein

During aerobic respiration, which of the following pathways correctly orders the process of cellular metabolism after glycolysis in eukaryotic cells? a) Pyruvate decarboxylation to Oxidative phosphorylation to Citric acid cycle b) Citric acid cycle to Oxidative phosphorylation to Pyruvate decarboxylation c) Citric acid cycle to Pyruvate decarboxylation to Oxidative phosphorylation d) Pyruvate decarboxylation to Citric acid cycle to Oxidative phosphorylation e) Pyruvate decarboxylation to Citric acid cycle to Oxidative phosphorylation

e) Pyruvate decarboxylation to Citric acid cycle to Oxidative phosphorylation