Quiz
Biochemistry Final Review
Fragen in diesem Quiz (71)
1Which of the following statements about the role of the PPP pathway is correct?
- Aa) The PPP produces ribose-5-P and NADPH
- Bb) THE PPP pathway oxidizes NADPH to NADP+
- Cc) The rate-limiting reaction of the PPP is catalyzed by transketolase
- Da) The PPP occurs in the mitochondria of most cells
2Which of the following statements about the oxidative section of the PPP is correct
- Aa) The PPP generates NADH
- Bb) THE PPP pathway oxidizes NADPH to NADP+
- Cc) The rate-limiting reaction of the PPP is catalyzed by G6P
- Dd) The PPP supplies ribose-5-P and NADPH in the quantities the cells require
3Which of the following statements about the non-oxidative section of the PPP is correct
- Aa) The non-oxidative reactions of the PPP are not reversible
- Bb) Transketolase is an enzyme that transfers three-carbon units in the PPP
- Cc) Transaldolase is an enzyme that transfers two-carbon units in the PPP
- Dd) Pentoses undergo isomerizations in the PPP
4Which of the following statements about the PPP is not true:
- Aa) The PPP relies on the availability of NADP+
- Bb) The PPP has an irreversible oxidative section and a reversible non-oxidative section
- Cc) The PPP enables excess ribose to be metabolized
- Dd) The PPP relies on the availability of NADPH
5Haemolytic anemia can be triggered in people deficient in glucose-6-phosphatatse by infections. What is the mechanism?
- Aa) Infection leads to increased production of immunoglobulins which attack the erythrocyte
- Bb) Infection is accomplished by generation of oxidants which destroy the erythrocyte membrane
- Cc) Infection leads to weakening of erythrocyte cell membranes by the attachment of bacterial toxins
- Dd) Infection compromises the immune system which is unable to protect the erythrocyte
6What is an important function of the PPP
- Aa) Generation of NADH for the production of ATP by the ETC
- Bb) Generation of NADPH for fatty acid synthesis
- Cc) Generation of NAD which is necessary for glycolysis
- Dd) Generation of NADP needed in amino acid metabolism
7Which of the following statements about the reactions of glycolysis is correct?
- AG6P is split into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate
- Bfructose-1,6-bisphosphate is split into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate
- Cfructose-6-phosphate is split into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate
- DG6P is isomerized to fructose-1,6-bisphosphate
8Which of the following statements about the glycolytic intermediate fructose-6-phosphate is correct?
- Afructose-6-phosphate is formed from G6P and is split by the aldol reaction into an aldehyde and a ketone
- Bfructose-6-phosphate is an aldol so once phosphorylated to F-1,6-BP cannot be split by the aldol reaction into an aldehyde and a ketone
- Cfructose-6-phosphate is converted to G6P and can then be split by the aldol reaction into an aldehyde and a ketone
- Dfructose-6-phosphate is an aldol but is not itself split by the aldol reaction until phosphorylated to F-1,6-BP
9Which of the following statements about the Citric Acid Cycle is correct?
- AOxygen is used to oxidize the acetyl group carbons of acetyl-CoA
- BThree molecules of NADH and one molecule of FADH2 are produced in one turn of the ycle
- COxygen is not used in the CA cycle, so the cycle can occur in anaerobic conditions
- DThe CA cycle produces the water that is formed during the complete oxidation of glucose
10Which of the following statements about the Electron Transport Chain is correct?
- AThe ETC is made up of a chain of electron carriers with decreasing electron affinity
- BThe ETC is made up of a chain of electron carriers with increasing redox potential
- CThe ETC is made up of a chain of electron carriers with decreasing oxidizing power
- DThe electrons transferred from carrier to carier in the ETC gain energy
11Glycogenolysis is inhibited by insulin
- ARichtig
- BFalsch
12Glycogenolysis is inhibited by glucagon and epinephrine
- ARichtig
- BFalsch
13Glycogenesis is the synthesis of glycogen from G6P
- ARichtig
- BFalsch
14Insulin inhibits glycogenolysis
- ARichtig
- BFalsch
15Insulin deactivates glycogenesis
- ARichtig
- BFalsch
16Epinephrine release activates glycogenolysis
- ARichtig
- BFalsch
17Epinephrine release inhibits glycogenesis
- ARichtig
- BFalsch
18Glucagon inhibits glycogen breakdown
- ARichtig
- BFalsch
19Glucagon activates liver gluconeogenesis
- ARichtig
- BFalsch
20Insulin is secreted from the liver in response to an increase in blood glucose
- ARichtig
- BFalsch
21Insulin's effect include:
- AStimulation of lipid synthesis
- BGlycogen synthesis
- CProtein Synthesis
- DGlycolysis and inhibition of gluconeogenesis and lipid breakdown
- EAll of the above
- FNone of the above
22Gluconeogenesis is the formation of new glucose molecules from precursors in the liver including:
- ALactate
- BPyruvate
- CAlpha-keto acids
- DAll of the above
- ENone of the above
23What is the net yield of ATP per glucose molecule that passes through all of aerobic respiration (glucose --> CO2 + H2O)?
- A2
- B4
- C6
- D32, depending on the shuttle system used
- ENone of the above
24What do cyanide, azide, and carbon monoxide all have in common?
- AThey are all products of combustion and contribute to smog
- BThey are all nitrogenous compounds
- CThey all inhibit the final step of electron transport
- DThey all bind to hemoglobin irreversibly
- EAll of the above
25Uncouplers are compounds that inhibit the phosphorylation of ADP:
- ABy enhancing the proton gradient across the outer mitochondrial membrane
- BBy enhancing the proton gradient across the inner mitochondrial membrane
- CBecause the are transmembrane proteins in the outer mitochondrial membrane
- DWithout affecting electron transport
26Coenzyme Q can act as an intermediate electron carrier, since the ketone group of the quinone structure is readily reduced to an alcohol
- ARichtig
- BFalsch
27In Eukaryotes the enzymes of the citric acid cycle are found in the:
- ANucleus
- BMitochondria
- CEndoplasmic Reticulum
- DCytosol
28A cytochrome that can move freely in the mitochondrial membrane is:
- ACytochrome a
- BCytochrome b
- CCytochrome c
- DCytochrome c1
29Which of the following enzymatic reactions are control points for glycolysis?
- AAldolase
- BGlucose-6-phosphate isomerase
- CBoth A and B
- DNeither A nor B
30The Q cycle refers to flow of electrons from
- ANADH to coenzyme Q via Complex I
- BFADH2 to coenzyme Q via Complex II
- CCoenzyme Q to cytochrome c via Complex III
- DCoenzyme Q to NADH
31The step in which acetyl-CoA enters the CA cycle is classified as what type of reaction?
- ADecarboxylation
- BDehydrogenation
- CCondensation
- Dsubstrate-level phosphorylation
32The following enzyme(s) is/are unique to the glyoxylate cycle
- Amalate synthase
- Bmalate dehydrogenase
- Cisocitrate lyase
- DAll of the above
- EA and C only
33Which complex in the electron transport chain carries electrons from cytochrome c to molecular oxygen, reducing it to water?
- AI
- BII
- CIII
- DIV
- EV
34The terminal electron acceptor for complex III of the ETC is:
- AFAD
- BQ
- CFe-S
- DCytochrome c
35The glyoxylate cycle leads from two-carbon compounds to glucose in each organism below, except:
- AYeast
- BAnimals
- CBacteria
- DPlants
- ENone of the above
36Which is a component of Complex I?
- AQ
- BFMN
- CTPP
- DFAD
37The glyoxylate cycle is:
- AA catabolic pathway in plants and some microorganisms
- BRegarded as a shunt within the citric acid cycle
- CAn anabolic pathway in plants and some microorganisms
- DA and C only
- EB and C only
38What feature of Cytochromes makes them valuable in electron transport systems?
- AThe porphyrin ring
- BAspartate residues in the active site
- CThe Iron Ion
- DThe multiple alpha-helices
39Complex II in the electron transport chain supplies electrons as what to teh rest of the chain (Complexes III and IV)
- AQH2
- BFADH2
- CFe-S
- DSuccinate
40Compare the pH of the mitochondrial matrix and the intermembrane space
- AThe pH is lower in the intermembrane space
- BThe pH in both regions is the same
- CThe pH is lower in the matrix
- DThe comparison of pH varies from moment to moment depending on energy needs of the cell
41How many protons are translocated across the inner mitochondrial membrane by Complex III for each pair of electrons passing through the ETC
- A0
- B1
- C2
- D4
42The P/O ratio refers to the number of moles of ATP produced for each moles of:
- AOxygen atoms consumed in electron transport
- BHydrogen molecules consumed in electron transport
- CNADH reoxidized in electron transport
- DFADH2 reoxidized in electron transport
43During glycolysis, isomerization occurs during which of the following reactions?
- AFructose-1,6-bisphosphate --> dihydroxyacetone phosphate and glyceraldehyde-3-phosphate
- BGlucose --> glucose-6-phosphate
- CFructose-6-phosphate --> fructose-1,6-bisphosphate
- DGlucose-6-phosphate --> fructose-6-phosphate
44Iron sulfur clusters (Fe-S) that can accept or donate one electron are found in which complexes of the electron transport chain?
- AI, II, III, and IV
- BII and III
- CI
- DI, II, and III
45The enzyme that catalyzes the conversion of pyruvate to lactate is:
- APyruvate kinase
- BLactate dehydrogenase
- CLactate reductase
- DLactoenolpyruvate
46The ultimate electron acceptor from complex II is:
- AQ
- BO2
- CQH2
- DFMN
- Ecytochrome c
47The proton motive force is a result of:
- Athe flow of protons within the inner mitochondrial membrane
- Ba combination of an electrical potential and a chemical potential
- Cthe flow of electrons from the matrix to the intermembrane space
- Dall of the above
48Which substance causes muscles to ache during strenuous exercise?
- APyruvic acid
- BLactic acid
- CLactate Ion
- DLactose dehydrogenase
49ATP synthase is located in what area of the mitochondrion?
- Amatrix
- Bintermembrane space
- Cinner membrane
- Douter membrane
50In the respiratory ETC electrons are passed from:
- ANADH and QH2 to O2
- BO2 to NAD+ and Q
- CATP to O2
- DO2 to NADH
51The citric acid cycle oxidizes pyruvate, and some of the pathway intermediates are starting materials for many biosynthetic pathways. This means the citric acid cycle is:
- AAnabolic
- BCatabolic
- CAmplifying
- DAmphibolic (catabolic and anabolic)
52The inner mitochondrial membrane contributes to the formation of a proton gradient mainly because it:
- Acontains ATP synthase complex
- Bis not rich in proteins
- Cis the location of specific transport proteins
- Dis a barrier to protons
- Eis rich in proteins
53Oxidative phosphorylation requires all of the items listed below, except:
- Aa terminal electron acceptor which is H2O in mitochondria
- Ba matrix more positively charged than the intermembrane space
- Cthe flow of electrons from NADH and QH2 in the membrane
- DATP synthase in the correct position in the membrane
- Eenzyme complexes embedded in the membrane
54Once inside a cell, glucose is rapidly phosphorylated to G6P. What is the main purpose of this phosphorylation?
- Ato activate phosphofructokinase-1
- Bto keep glucose inside the cell
- Cto form a high-energy compound
- Dto prevent mutarotation
55In the mitochondria NADH and QH2 are essentially oxidized by ____________ since it is the terminal electron acceptor
- AOzone
- BHydrogen Peroxide
- CCarbon Dioxide
- DOxygen
56Heat can be generated in the brown adipose tissue of hibernating mammals due to _______________:
- Aincreased ATP production by ATP synthase
- Ba greater pH gradient across the inner mitochondrial membrane by complex IV
- Cuncoupling by thermogenin
- Dinsufficient NADH production during the citric acid cycle due to less active pyruvate translocases
57How many protons are translocated across the inner mitochondrial membrane by complex IV for every pair of electrons passing the electron transport chain?
- A0
- B1
- C2
- D3
- E4
58Which enzyme catalyzes the conversion of citrate to isocitrate?
- AAldolase
- BCitrate isomerase
- CAconitase
- DCitrate synthase
59Which step int he citric acid cycle is a rearrangement reaction?
- Acitrate to isocitrate
- Bsuccinyl-CoA to succinate
- Cfumarate to L-malate
- Dglucose-1,6-bisphosphate to fructose-1,6-bisphosphate
60Which 5-carbon intermediate of the citric acid cycle is converted to a 4-carbon molecule with the release of Carbon dioxide
- Aisocitrate
- Bsuccinate
- Calpha-ketoglutarate
- Dfumerase
61Pyruvate passes through the outer mitochondrial membrane by _____________?
- APorin proteins
- Bsimple diffusion through the lipid bilayer
- Cpyruvate translocase
- Dpassive transport
62What type of reaction is the conversion of fumarate to malate?
- Acondensation
- Boxidative decarboxylation
- Cdehydrogenation
- Dhydration
63Which cofactor is NOT used by the pyruvate dehydrogenase complex?
- AQH2
- BFAD
- Cthiamine pyrophosphate
- Dlipoamide
642,3-bisphosphoglycerate is:
- Aessential for the efficient release of O2 from hemoglobin
- Ba product of the enzyme phosphofructokinase
- Cconverted to 3-phosphoglycerate with formation of ATP
- Dan essential component of glycolysis for ATP production
65Which of the following elements is required for the enzymatic reaction that produces phosphoenolpyruvate?
- AManganese
- BPotassium
- CMagnesium
- DCalcium
66What two isomerization reactions occur in glycolysis? Why are these steps necessary
- AGlucose-6-phosphate is isomerized to fructose-6-phosphate, converting an aldose to a ketose, which then allows phosphorylation at the number 1 carbon
- BLater in the pathway, dihydroxyacetone is converted to glyceraldehyde-3-phosphate, utilizing both of the molecules formed from fructose-1,6-bisphosphate cleavage
67How is glycolysis maintained under anaerobic conditions?
- APyruvate can be reduced to either lactate or ethanol, and this reaction is accompanied by the oxidation of NADH to regenerate NAD+
- BFermentation reactions ^^ lactic or alcoholic fermentation
68How does citrate influence glycolysis?
- APhosphofructokinase is inhibited by citrate, which is an intermediate in the citric acid cycle
- BThus, if citrate levels are high, the enzyme is inhibited, and fewer glucose molecules are metabolized
- CIn this sense, citrate serves as a cell indicator
- DHigh levels of citrate in the cytoplasm means that biosynthetic precursors are abundant, and sot here is no need to degrade additional glucose for this purpose
69Describe the two isoforms of lactate dehydrogenase
- ATwo forms exist, called M and H, which predominate in the skeletal and heart muscle, respectively
- BThe two forms are products of different genes, but are similar in structure, and can form tetramers in various H:M ratios
- CThe two forms differ in their sensitivity to pyruvate
- DH+ functions primarily to oxidize lactate to pyruvate, which serves as a fuel for aerobic metabolism. In contrast, M4 produces lactate so that glycolysis can continue under anaerobic conditions
70Why is it necessary that there be a mechanism to replenish oxaloacetate?
- ADuring periods of biosynthesis, oxaloacetate may be converted to amino acids for protein synthesis
- BEven if acetyl-CoA will operate at reduced levels until new oxaloacetate is formed
71How is succinate dehydrogenase unique when compared to the other enzymes in the citric acid cycle
- AIt is the only enzyme embedded in the mitochondrial membrane
- BIt is directly associated with the electron transport chain
Informationen
- Beschreibung
- 3rd year undergraduate biochemistry final exam review - glycolysis to Cori cycle
- Autor
- Kaitlyn Emily Bi
- Sprache
- English
- Aufrufe
- 317
- Schlagwörter
- Bewertung
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