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Biochemistry Final Review

Beschreibung

3rd year undergraduate biochemistry final exam review - glycolysis to Cori cycle
Kaitlyn Emily Bi
Quiz von Kaitlyn Emily Bi, aktualisiert more than 1 year ago
Kaitlyn Emily Bi
Erstellt von Kaitlyn Emily Bi vor etwa 9 Jahre
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Zusammenfassung der Ressource

Frage 1

Frage
Which of the following statements about the role of the PPP pathway is correct?
Antworten
  • a) The PPP produces ribose-5-P and NADPH
  • b) THE PPP pathway oxidizes NADPH to NADP+
  • c) The rate-limiting reaction of the PPP is catalyzed by transketolase
  • a) The PPP occurs in the mitochondria of most cells

Frage 2

Frage
Which of the following statements about the oxidative section of the PPP is correct
Antworten
  • a) The PPP generates NADH
  • b) THE PPP pathway oxidizes NADPH to NADP+
  • c) The rate-limiting reaction of the PPP is catalyzed by G6P
  • d) The PPP supplies ribose-5-P and NADPH in the quantities the cells require

Frage 3

Frage
Which of the following statements about the non-oxidative section of the PPP is correct
Antworten
  • a) The non-oxidative reactions of the PPP are not reversible
  • b) Transketolase is an enzyme that transfers three-carbon units in the PPP
  • c) Transaldolase is an enzyme that transfers two-carbon units in the PPP
  • d) Pentoses undergo isomerizations in the PPP

Frage 4

Frage
Which of the following statements about the PPP is not true:
Antworten
  • a) The PPP relies on the availability of NADP+
  • b) The PPP has an irreversible oxidative section and a reversible non-oxidative section
  • c) The PPP enables excess ribose to be metabolized
  • d) The PPP relies on the availability of NADPH

Frage 5

Frage
Haemolytic anemia can be triggered in people deficient in glucose-6-phosphatatse by infections. What is the mechanism?
Antworten
  • a) Infection leads to increased production of immunoglobulins which attack the erythrocyte
  • b) Infection is accomplished by generation of oxidants which destroy the erythrocyte membrane
  • c) Infection leads to weakening of erythrocyte cell membranes by the attachment of bacterial toxins
  • d) Infection compromises the immune system which is unable to protect the erythrocyte

Frage 6

Frage
What is an important function of the PPP
Antworten
  • a) Generation of NADH for the production of ATP by the ETC
  • b) Generation of NADPH for fatty acid synthesis
  • c) Generation of NAD which is necessary for glycolysis
  • d) Generation of NADP needed in amino acid metabolism

Frage 7

Frage
Which of the following statements about the reactions of glycolysis is correct?
Antworten
  • G6P is split into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate
  • fructose-1,6-bisphosphate is split into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate
  • fructose-6-phosphate is split into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate
  • G6P is isomerized to fructose-1,6-bisphosphate

Frage 8

Frage
Which of the following statements about the glycolytic intermediate fructose-6-phosphate is correct?
Antworten
  • fructose-6-phosphate is formed from G6P and is split by the aldol reaction into an aldehyde and a ketone
  • fructose-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
  • fructose-6-phosphate is converted to G6P and can then be split by the aldol reaction into an aldehyde and a ketone
  • fructose-6-phosphate is an aldol but is not itself split by the aldol reaction until phosphorylated to F-1,6-BP

Frage 9

Frage
Which of the following statements about the Citric Acid Cycle is correct?
Antworten
  • Oxygen is used to oxidize the acetyl group carbons of acetyl-CoA
  • Three molecules of NADH and one molecule of FADH2 are produced in one turn of the ycle
  • Oxygen is not used in the CA cycle, so the cycle can occur in anaerobic conditions
  • The CA cycle produces the water that is formed during the complete oxidation of glucose

Frage 10

Frage
Which of the following statements about the Electron Transport Chain is correct?
Antworten
  • The ETC is made up of a chain of electron carriers with decreasing electron affinity
  • The ETC is made up of a chain of electron carriers with increasing redox potential
  • The ETC is made up of a chain of electron carriers with decreasing oxidizing power
  • The electrons transferred from carrier to carier in the ETC gain energy

Frage 11

Frage
Glycogenolysis is inhibited by insulin
Antworten
  • True
  • False

Frage 12

Frage
Glycogenolysis is inhibited by glucagon and epinephrine
Antworten
  • True
  • False

Frage 13

Frage
Glycogenesis is the synthesis of glycogen from G6P
Antworten
  • True
  • False

Frage 14

Frage
Insulin inhibits glycogenolysis
Antworten
  • True
  • False

Frage 15

Frage
Insulin deactivates glycogenesis
Antworten
  • True
  • False

Frage 16

Frage
Epinephrine release activates glycogenolysis
Antworten
  • True
  • False

Frage 17

Frage
Epinephrine release inhibits glycogenesis
Antworten
  • True
  • False

Frage 18

Frage
Glucagon inhibits glycogen breakdown
Antworten
  • True
  • False

Frage 19

Frage
Glucagon activates liver gluconeogenesis
Antworten
  • True
  • False

Frage 20

Frage
Insulin is secreted from the liver in response to an increase in blood glucose
Antworten
  • True
  • False

Frage 21

Frage
Insulin's effect include:
Antworten
  • Stimulation of lipid synthesis
  • Glycogen synthesis
  • Protein Synthesis
  • Glycolysis and inhibition of gluconeogenesis and lipid breakdown
  • All of the above
  • None of the above

Frage 22

Frage
Gluconeogenesis is the formation of new glucose molecules from precursors in the liver including:
Antworten
  • Lactate
  • Pyruvate
  • Alpha-keto acids
  • All of the above
  • None of the above

Frage 23

Frage
What is the net yield of ATP per glucose molecule that passes through all of aerobic respiration (glucose --> CO2 + H2O)?
Antworten
  • 2
  • 4
  • 6
  • 32, depending on the shuttle system used
  • None of the above

Frage 24

Frage
What do cyanide, azide, and carbon monoxide all have in common?
Antworten
  • They are all products of combustion and contribute to smog
  • They are all nitrogenous compounds
  • They all inhibit the final step of electron transport
  • They all bind to hemoglobin irreversibly
  • All of the above

Frage 25

Frage
Uncouplers are compounds that inhibit the phosphorylation of ADP:
Antworten
  • By enhancing the proton gradient across the outer mitochondrial membrane
  • By enhancing the proton gradient across the inner mitochondrial membrane
  • Because the are transmembrane proteins in the outer mitochondrial membrane
  • Without affecting electron transport

Frage 26

Frage
Coenzyme Q can act as an intermediate electron carrier, since the ketone group of the quinone structure is readily reduced to an alcohol
Antworten
  • True
  • False

Frage 27

Frage
In Eukaryotes the enzymes of the citric acid cycle are found in the:
Antworten
  • Nucleus
  • Mitochondria
  • Endoplasmic Reticulum
  • Cytosol

Frage 28

Frage
A cytochrome that can move freely in the mitochondrial membrane is:
Antworten
  • Cytochrome a
  • Cytochrome b
  • Cytochrome c
  • Cytochrome c1

Frage 29

Frage
Which of the following enzymatic reactions are control points for glycolysis?
Antworten
  • Aldolase
  • Glucose-6-phosphate isomerase
  • Both A and B
  • Neither A nor B

Frage 30

Frage
The Q cycle refers to flow of electrons from
Antworten
  • NADH to coenzyme Q via Complex I
  • FADH2 to coenzyme Q via Complex II
  • Coenzyme Q to cytochrome c via Complex III
  • Coenzyme Q to NADH

Frage 31

Frage
The step in which acetyl-CoA enters the CA cycle is classified as what type of reaction?
Antworten
  • Decarboxylation
  • Dehydrogenation
  • Condensation
  • substrate-level phosphorylation

Frage 32

Frage
The following enzyme(s) is/are unique to the glyoxylate cycle
Antworten
  • malate synthase
  • malate dehydrogenase
  • isocitrate lyase
  • All of the above
  • A and C only

Frage 33

Frage
Which complex in the electron transport chain carries electrons from cytochrome c to molecular oxygen, reducing it to water?
Antworten
  • I
  • II
  • III
  • IV
  • V

Frage 34

Frage
The terminal electron acceptor for complex III of the ETC is:
Antworten
  • FAD
  • Q
  • Fe-S
  • Cytochrome c

Frage 35

Frage
The glyoxylate cycle leads from two-carbon compounds to glucose in each organism below, except:
Antworten
  • Yeast
  • Animals
  • Bacteria
  • Plants
  • None of the above

Frage 36

Frage
Which is a component of Complex I?
Antworten
  • Q
  • FMN
  • TPP
  • FAD

Frage 37

Frage
The glyoxylate cycle is:
Antworten
  • A catabolic pathway in plants and some microorganisms
  • Regarded as a shunt within the citric acid cycle
  • An anabolic pathway in plants and some microorganisms
  • A and C only
  • B and C only

Frage 38

Frage
What feature of Cytochromes makes them valuable in electron transport systems?
Antworten
  • The porphyrin ring
  • Aspartate residues in the active site
  • The Iron Ion
  • The multiple alpha-helices

Frage 39

Frage
Complex II in the electron transport chain supplies electrons as what to teh rest of the chain (Complexes III and IV)
Antworten
  • QH2
  • FADH2
  • Fe-S
  • Succinate

Frage 40

Frage
Compare the pH of the mitochondrial matrix and the intermembrane space
Antworten
  • The pH is lower in the intermembrane space
  • The pH in both regions is the same
  • The pH is lower in the matrix
  • The comparison of pH varies from moment to moment depending on energy needs of the cell

Frage 41

Frage
How many protons are translocated across the inner mitochondrial membrane by Complex III for each pair of electrons passing through the ETC
Antworten
  • 0
  • 1
  • 2
  • 4

Frage 42

Frage
The P/O ratio refers to the number of moles of ATP produced for each moles of:
Antworten
  • Oxygen atoms consumed in electron transport
  • Hydrogen molecules consumed in electron transport
  • NADH reoxidized in electron transport
  • FADH2 reoxidized in electron transport

Frage 43

Frage
During glycolysis, isomerization occurs during which of the following reactions?
Antworten
  • Fructose-1,6-bisphosphate --> dihydroxyacetone phosphate and glyceraldehyde-3-phosphate
  • Glucose --> glucose-6-phosphate
  • Fructose-6-phosphate --> fructose-1,6-bisphosphate
  • Glucose-6-phosphate --> fructose-6-phosphate

Frage 44

Frage
Iron sulfur clusters (Fe-S) that can accept or donate one electron are found in which complexes of the electron transport chain?
Antworten
  • I, II, III, and IV
  • II and III
  • I
  • I, II, and III

Frage 45

Frage
The enzyme that catalyzes the conversion of pyruvate to lactate is:
Antworten
  • Pyruvate kinase
  • Lactate dehydrogenase
  • Lactate reductase
  • Lactoenolpyruvate

Frage 46

Frage
The ultimate electron acceptor from complex II is:
Antworten
  • Q
  • O2
  • QH2
  • FMN
  • cytochrome c

Frage 47

Frage
The proton motive force is a result of:
Antworten
  • the flow of protons within the inner mitochondrial membrane
  • a combination of an electrical potential and a chemical potential
  • the flow of electrons from the matrix to the intermembrane space
  • all of the above

Frage 48

Frage
Which substance causes muscles to ache during strenuous exercise?
Antworten
  • Pyruvic acid
  • Lactic acid
  • Lactate Ion
  • Lactose dehydrogenase

Frage 49

Frage
ATP synthase is located in what area of the mitochondrion?
Antworten
  • matrix
  • intermembrane space
  • inner membrane
  • outer membrane

Frage 50

Frage
In the respiratory ETC electrons are passed from:
Antworten
  • NADH and QH2 to O2
  • O2 to NAD+ and Q
  • ATP to O2
  • O2 to NADH

Frage 51

Frage
The 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:
Antworten
  • Anabolic
  • Catabolic
  • Amplifying
  • Amphibolic (catabolic and anabolic)

Frage 52

Frage
The inner mitochondrial membrane contributes to the formation of a proton gradient mainly because it:
Antworten
  • contains ATP synthase complex
  • is not rich in proteins
  • is the location of specific transport proteins
  • is a barrier to protons
  • is rich in proteins

Frage 53

Frage
Oxidative phosphorylation requires all of the items listed below, except:
Antworten
  • a terminal electron acceptor which is H2O in mitochondria
  • a matrix more positively charged than the intermembrane space
  • the flow of electrons from NADH and QH2 in the membrane
  • ATP synthase in the correct position in the membrane
  • enzyme complexes embedded in the membrane

Frage 54

Frage
Once inside a cell, glucose is rapidly phosphorylated to G6P. What is the main purpose of this phosphorylation?
Antworten
  • to activate phosphofructokinase-1
  • to keep glucose inside the cell
  • to form a high-energy compound
  • to prevent mutarotation

Frage 55

Frage
In the mitochondria NADH and QH2 are essentially oxidized by ____________ since it is the terminal electron acceptor
Antworten
  • Ozone
  • Hydrogen Peroxide
  • Carbon Dioxide
  • Oxygen

Frage 56

Frage
Heat can be generated in the brown adipose tissue of hibernating mammals due to _______________:
Antworten
  • increased ATP production by ATP synthase
  • a greater pH gradient across the inner mitochondrial membrane by complex IV
  • uncoupling by thermogenin
  • insufficient NADH production during the citric acid cycle due to less active pyruvate translocases

Frage 57

Frage
How many protons are translocated across the inner mitochondrial membrane by complex IV for every pair of electrons passing the electron transport chain?
Antworten
  • 0
  • 1
  • 2
  • 3
  • 4

Frage 58

Frage
Which enzyme catalyzes the conversion of citrate to isocitrate?
Antworten
  • Aldolase
  • Citrate isomerase
  • Aconitase
  • Citrate synthase

Frage 59

Frage
Which step int he citric acid cycle is a rearrangement reaction?
Antworten
  • citrate to isocitrate
  • succinyl-CoA to succinate
  • fumarate to L-malate
  • glucose-1,6-bisphosphate to fructose-1,6-bisphosphate

Frage 60

Frage
Which 5-carbon intermediate of the citric acid cycle is converted to a 4-carbon molecule with the release of Carbon dioxide
Antworten
  • isocitrate
  • succinate
  • alpha-ketoglutarate
  • fumerase

Frage 61

Frage
Pyruvate passes through the outer mitochondrial membrane by _____________?
Antworten
  • Porin proteins
  • simple diffusion through the lipid bilayer
  • pyruvate translocase
  • passive transport

Frage 62

Frage
What type of reaction is the conversion of fumarate to malate?
Antworten
  • condensation
  • oxidative decarboxylation
  • dehydrogenation
  • hydration

Frage 63

Frage
Which cofactor is NOT used by the pyruvate dehydrogenase complex?
Antworten
  • QH2
  • FAD
  • thiamine pyrophosphate
  • lipoamide

Frage 64

Frage
2,3-bisphosphoglycerate is:
Antworten
  • essential for the efficient release of O2 from hemoglobin
  • a product of the enzyme phosphofructokinase
  • converted to 3-phosphoglycerate with formation of ATP
  • an essential component of glycolysis for ATP production

Frage 65

Frage
Which of the following elements is required for the enzymatic reaction that produces phosphoenolpyruvate?
Antworten
  • Manganese
  • Potassium
  • Magnesium
  • Calcium

Frage 66

Frage
What two isomerization reactions occur in glycolysis? Why are these steps necessary
Antworten
  • Glucose-6-phosphate is isomerized to fructose-6-phosphate, converting an aldose to a ketose, which then allows phosphorylation at the number 1 carbon
  • Later in the pathway, dihydroxyacetone is converted to glyceraldehyde-3-phosphate, utilizing both of the molecules formed from fructose-1,6-bisphosphate cleavage

Frage 67

Frage
How is glycolysis maintained under anaerobic conditions?
Antworten
  • Pyruvate can be reduced to either lactate or ethanol, and this reaction is accompanied by the oxidation of NADH to regenerate NAD+
  • Fermentation reactions ^^ lactic or alcoholic fermentation

Frage 68

Frage
How does citrate influence glycolysis?
Antworten
  • Phosphofructokinase is inhibited by citrate, which is an intermediate in the citric acid cycle
  • Thus, if citrate levels are high, the enzyme is inhibited, and fewer glucose molecules are metabolized
  • In this sense, citrate serves as a cell indicator
  • High 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

Frage 69

Frage
Describe the two isoforms of lactate dehydrogenase
Antworten
  • Two forms exist, called M and H, which predominate in the skeletal and heart muscle, respectively
  • The two forms are products of different genes, but are similar in structure, and can form tetramers in various H:M ratios
  • The two forms differ in their sensitivity to pyruvate
  • H+ 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

Frage 70

Frage
Why is it necessary that there be a mechanism to replenish oxaloacetate?
Antworten
  • During periods of biosynthesis, oxaloacetate may be converted to amino acids for protein synthesis
  • Even if acetyl-CoA will operate at reduced levels until new oxaloacetate is formed

Frage 71

Frage
How is succinate dehydrogenase unique when compared to the other enzymes in the citric acid cycle
Antworten
  • It is the only enzyme embedded in the mitochondrial membrane
  • It is directly associated with the electron transport chain
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