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3rd year undergraduate biochemistry final exam review - glycolysis to Cori cycle

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Biochemistry Final Review

Question 1 of 71

1

Which of the following statements about the role of the PPP pathway is correct?

Select one of the following:

  • 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

Explanation

Question 2 of 71

1

Which of the following statements about the oxidative section of the PPP is correct

Select one of the following:

  • 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

Explanation

Question 3 of 71

1

Which of the following statements about the non-oxidative section of the PPP is correct

Select one of the following:

  • 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

Explanation

Question 4 of 71

1

Which of the following statements about the PPP is not true:

Select one of the following:

  • 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

Explanation

Question 5 of 71

1

Haemolytic anemia can be triggered in people deficient in glucose-6-phosphatatse by infections. What is the mechanism?

Select one of the following:

  • 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

Explanation

Question 6 of 71

1

What is an important function of the PPP

Select one of the following:

  • 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

Explanation

Question 7 of 71

1

Which of the following statements about the reactions of glycolysis is correct?

Select one of the following:

  • 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

Explanation

Question 8 of 71

1

Which of the following statements about the glycolytic intermediate fructose-6-phosphate is correct?

Select one of the following:

  • 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

Explanation

Question 9 of 71

1

Which of the following statements about the Citric Acid Cycle is correct?

Select one of the following:

  • 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

Explanation

Question 10 of 71

1

Which of the following statements about the Electron Transport Chain is correct?

Select one of the following:

  • 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

Explanation

Question 11 of 71

1

Glycogenolysis is inhibited by insulin

Select one of the following:

  • True
  • False

Explanation

Question 12 of 71

1

Glycogenolysis is inhibited by glucagon and epinephrine

Select one of the following:

  • True
  • False

Explanation

Question 13 of 71

1

Glycogenesis is the synthesis of glycogen from G6P

Select one of the following:

  • True
  • False

Explanation

Question 14 of 71

1

Insulin inhibits glycogenolysis

Select one of the following:

  • True
  • False

Explanation

Question 15 of 71

1

Insulin deactivates glycogenesis

Select one of the following:

  • True
  • False

Explanation

Question 16 of 71

1

Epinephrine release activates glycogenolysis

Select one of the following:

  • True
  • False

Explanation

Question 17 of 71

1

Epinephrine release inhibits glycogenesis

Select one of the following:

  • True
  • False

Explanation

Question 18 of 71

1

Glucagon inhibits glycogen breakdown

Select one of the following:

  • True
  • False

Explanation

Question 19 of 71

1

Glucagon activates liver gluconeogenesis

Select one of the following:

  • True
  • False

Explanation

Question 20 of 71

1

Insulin is secreted from the liver in response to an increase in blood glucose

Select one of the following:

  • True
  • False

Explanation

Question 21 of 71

1

Insulin's effect include:

Select one of the following:

  • Stimulation of lipid synthesis

  • Glycogen synthesis

  • Protein Synthesis

  • Glycolysis and inhibition of gluconeogenesis and lipid breakdown

  • All of the above

  • None of the above

Explanation

Question 22 of 71

1

Gluconeogenesis is the formation of new glucose molecules from precursors in the liver including:

Select one of the following:

  • Lactate

  • Pyruvate

  • Alpha-keto acids

  • All of the above

  • None of the above

Explanation

Question 23 of 71

1

What is the net yield of ATP per glucose molecule that passes through all of aerobic respiration (glucose --> CO2 + H2O)?

Select one of the following:

  • 2

  • 4

  • 6

  • 32, depending on the shuttle system used

  • None of the above

Explanation

Question 24 of 71

1

What do cyanide, azide, and carbon monoxide all have in common?

Select one of the following:

  • 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

Explanation

Question 25 of 71

1

Uncouplers are compounds that inhibit the phosphorylation of ADP:

Select one of the following:

  • 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

Explanation

Question 26 of 71

1

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

Select one of the following:

  • True
  • False

Explanation

Question 27 of 71

1

In Eukaryotes the enzymes of the citric acid cycle are found in the:

Select one of the following:

  • Nucleus

  • Mitochondria

  • Endoplasmic Reticulum

  • Cytosol

Explanation

Question 28 of 71

1

A cytochrome that can move freely in the mitochondrial membrane is:

Select one of the following:

  • Cytochrome a

  • Cytochrome b

  • Cytochrome c

  • Cytochrome c1

Explanation

Question 29 of 71

1

Which of the following enzymatic reactions are control points for glycolysis?

Select one of the following:

  • Aldolase

  • Glucose-6-phosphate isomerase

  • Both A and B

  • Neither A nor B

Explanation

Question 30 of 71

1

The Q cycle refers to flow of electrons from

Select one of the following:

  • 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

Explanation

Question 31 of 71

1

The step in which acetyl-CoA enters the CA cycle is classified as what type of reaction?

Select one of the following:

  • Decarboxylation

  • Dehydrogenation

  • Condensation

  • substrate-level phosphorylation

Explanation

Question 32 of 71

1

The following enzyme(s) is/are unique to the glyoxylate cycle

Select one of the following:

  • malate synthase

  • malate dehydrogenase

  • isocitrate lyase

  • All of the above

  • A and C only

Explanation

Question 33 of 71

1

Which complex in the electron transport chain carries electrons from cytochrome c to molecular oxygen, reducing it to water?

Select one of the following:

  • I

  • II

  • III

  • IV

  • V

Explanation

Question 34 of 71

1

The terminal electron acceptor for complex III of the ETC is:

Select one of the following:

  • FAD

  • Q

  • Fe-S

  • Cytochrome c

Explanation

Question 35 of 71

1

The glyoxylate cycle leads from two-carbon compounds to glucose in each organism below, except:

Select one of the following:

  • Yeast

  • Animals

  • Bacteria

  • Plants

  • None of the above

Explanation

Question 36 of 71

1

Which is a component of Complex I?

Select one of the following:

  • Q

  • FMN

  • TPP

  • FAD

Explanation

Question 37 of 71

1

The glyoxylate cycle is:

Select one of the following:

  • 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

Explanation

Question 38 of 71

1

What feature of Cytochromes makes them valuable in electron transport systems?

Select one of the following:

  • The porphyrin ring

  • Aspartate residues in the active site

  • The Iron Ion

  • The multiple alpha-helices

Explanation

Question 39 of 71

1

Complex II in the electron transport chain supplies electrons as what to teh rest of the chain (Complexes III and IV)

Select one of the following:

  • QH2

  • FADH2

  • Fe-S

  • Succinate

Explanation

Question 40 of 71

1

Compare the pH of the mitochondrial matrix and the intermembrane space

Select one of the following:

  • 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

Explanation

Question 41 of 71

1

How many protons are translocated across the inner mitochondrial membrane by Complex III for each pair of electrons passing through the ETC

Select one of the following:

  • 0

  • 1

  • 2

  • 4

Explanation

Question 42 of 71

1

The P/O ratio refers to the number of moles of ATP produced for each moles of:

Select one of the following:

  • Oxygen atoms consumed in electron transport

  • Hydrogen molecules consumed in electron transport

  • NADH reoxidized in electron transport

  • FADH2 reoxidized in electron transport

Explanation

Question 43 of 71

1

During glycolysis, isomerization occurs during which of the following reactions?

Select one of the following:

  • 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

Explanation

Question 44 of 71

1

Iron sulfur clusters (Fe-S) that can accept or donate one electron are found in which complexes of the electron transport chain?

Select one of the following:

  • I, II, III, and IV

  • II and III

  • I

  • I, II, and III

Explanation

Question 45 of 71

1

The enzyme that catalyzes the conversion of pyruvate to lactate is:

Select one of the following:

  • Pyruvate kinase

  • Lactate dehydrogenase

  • Lactate reductase

  • Lactoenolpyruvate

Explanation

Question 46 of 71

1

The ultimate electron acceptor from complex II is:

Select one of the following:

  • Q

  • O2

  • QH2

  • FMN

  • cytochrome c

Explanation

Question 47 of 71

1

The proton motive force is a result of:

Select one of the following:

  • 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

Explanation

Question 48 of 71

1

Which substance causes muscles to ache during strenuous exercise?

Select one of the following:

  • Pyruvic acid

  • Lactic acid

  • Lactate Ion

  • Lactose dehydrogenase

Explanation

Question 49 of 71

1

ATP synthase is located in what area of the mitochondrion?

Select one of the following:

  • matrix

  • intermembrane space

  • inner membrane

  • outer membrane

Explanation

Question 50 of 71

1

In the respiratory ETC electrons are passed from:

Select one of the following:

  • NADH and QH2 to O2

  • O2 to NAD+ and Q

  • ATP to O2

  • O2 to NADH

Explanation

Question 51 of 71

1

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:

Select one of the following:

  • Anabolic

  • Catabolic

  • Amplifying

  • Amphibolic (catabolic and anabolic)

Explanation

Question 52 of 71

1

The inner mitochondrial membrane contributes to the formation of a proton gradient mainly because it:

Select one of the following:

  • 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

Explanation

Question 53 of 71

1

Oxidative phosphorylation requires all of the items listed below, except:

Select one of the following:

  • 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

Explanation

Question 54 of 71

1

Once inside a cell, glucose is rapidly phosphorylated to G6P. What is the main purpose of this phosphorylation?

Select one of the following:

  • to activate phosphofructokinase-1

  • to keep glucose inside the cell

  • to form a high-energy compound

  • to prevent mutarotation

Explanation

Question 55 of 71

1

In the mitochondria NADH and QH2 are essentially oxidized by ____________ since it is the terminal electron acceptor

Select one of the following:

  • Ozone

  • Hydrogen Peroxide

  • Carbon Dioxide

  • Oxygen

Explanation

Question 56 of 71

1

Heat can be generated in the brown adipose tissue of hibernating mammals due to _______________:

Select one of the following:

  • 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

Explanation

Question 57 of 71

1

How many protons are translocated across the inner mitochondrial membrane by complex IV for every pair of electrons passing the electron transport chain?

Select one of the following:

  • 0

  • 1

  • 2

  • 3

  • 4

Explanation

Question 58 of 71

1

Which enzyme catalyzes the conversion of citrate to isocitrate?

Select one of the following:

  • Aldolase

  • Citrate isomerase

  • Aconitase

  • Citrate synthase

Explanation

Question 59 of 71

1

Which step int he citric acid cycle is a rearrangement reaction?

Select one of the following:

  • citrate to isocitrate

  • succinyl-CoA to succinate

  • fumarate to L-malate

  • glucose-1,6-bisphosphate to fructose-1,6-bisphosphate

Explanation

Question 60 of 71

1

Which 5-carbon intermediate of the citric acid cycle is converted to a 4-carbon molecule with the release of Carbon dioxide

Select one of the following:

  • isocitrate

  • succinate

  • alpha-ketoglutarate

  • fumerase

Explanation

Question 61 of 71

1

Pyruvate passes through the outer mitochondrial membrane by _____________?

Select one of the following:

  • Porin proteins

  • simple diffusion through the lipid bilayer

  • pyruvate translocase

  • passive transport

Explanation

Question 62 of 71

1

What type of reaction is the conversion of fumarate to malate?

Select one of the following:

  • condensation

  • oxidative decarboxylation

  • dehydrogenation

  • hydration

Explanation

Question 63 of 71

1

Which cofactor is NOT used by the pyruvate dehydrogenase complex?

Select one of the following:

  • QH2

  • FAD

  • thiamine pyrophosphate

  • lipoamide

Explanation

Question 64 of 71

1

2,3-bisphosphoglycerate is:

Select one of the following:

  • 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

Explanation

Question 65 of 71

1

Which of the following elements is required for the enzymatic reaction that produces phosphoenolpyruvate?

Select one of the following:

  • Manganese

  • Potassium

  • Magnesium

  • Calcium

Explanation

Question 66 of 71

1

What two isomerization reactions occur in glycolysis? Why are these steps necessary

Select one or more of the following:

  • 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

Explanation

Question 67 of 71

1

How is glycolysis maintained under anaerobic conditions?

Select one or more of the following:

  • 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

Explanation

Question 68 of 71

1

How does citrate influence glycolysis?

Select one or more of the following:

  • 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

Explanation

Question 69 of 71

1

Describe the two isoforms of lactate dehydrogenase

Select one or more of the following:

  • 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

Explanation

Question 70 of 71

1

Why is it necessary that there be a mechanism to replenish oxaloacetate?

Select one or more of the following:

  • 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

Explanation

Question 71 of 71

1

How is succinate dehydrogenase unique when compared to the other enzymes in the citric acid cycle

Select one or more of the following:

  • It is the only enzyme embedded in the mitochondrial membrane

  • It is directly associated with the electron transport chain

Explanation

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