Exam 2 Flashcards Preview

The minimum amount of energy required to bring about a chemical reaction is called:

Which of the following is not a property of enzymes?

A) Capable of being regulated

B) Reaction rates high in comparison to uncatalyzed  reaction

C) Highly specific

D) Side products of reactions are rare

E) All of the above are true

Consider the following reaction diagram. Which letter indicates the transition state?

In contrast to inorganic catalysts, enzymes have an intricately shaped surface called the __________.

The lock and key model of enzyme activity proposes that each:

The synthesis of enzymes in response to changing metabolic needs is referred to as:

Which of the following is a coenzyme?

Alcohol dehydrogenase without NAD+ is called a _______:

The term synthetase is included in which class of enzymes?

Which of the following is not a type of oxidoreductase?

A Peroxidase

B) Hydroxylase

C) Reductase

D) Dehydrogenase

E) Peptidase

Which of the following classes of enzymes catalyze reactions involving the cleavage of bonds by the addition of water?

Consider the following reaction data.

Alanylanine + water -----à  alanine

[alanylanine}                                       [water]              Rate

0.1                                                       0.1                   1x 10-4

0.2                                                       0.1                   2x10-4

0.1                                                       0.2                   2x10-4

0.2                                                       0.2                   4x10-4

The reaction is _______ order overall.

The steady state assumption states that if:

K₁ = the rate constant for ES formation

K₂ = the rate constant for ES dissociation

K₃ = the rate constant for product formation

The expression of the Michaelis constant is equal to:

Where

K₁ = the rate constant for ES formation

K₂ = the rate constant for ES dissociation

K₃ = the rate constant for product formation

Specific activity is defined as

In the Lineweaver-Burk double reciprocal plot the slope is equal to _____.

In the Lineweaver-Burke double reciprocal plot the vertical intercept is equal to ____.

In the Lineweaver-Burke double reciprocal plot the horizontal intercept is equal to _________.

In competitive inhibition, increasing the concentration of substrate:

Which of the following amino acids is capable of acting as a general acid or general base at physiological pH ?

Which of the following amino acids can participate in covalent catalysis?

A) Tryptophan

B) Tyrosine

C) Serine

D) Histidine

E) Both C and D are correct

Which of the following is a feature of transition metals that makes them efficient cofactors?

A) Have a high concentration of positive charge

B) Can act as a Lewis acid

C) Have directed valences

D) Can exist as a variety of valence states

E) All of the above are correct

NADPH and NADH are coenzymes found in which class of enzymes?

Which of the following is not present in the active site of alcohol dehydrogenase?

A) Zn++

B) Histidine

C) Cysteine

D) NAD+

E) Proline

Enzyme control is accomplished in which of the following ways?

A) Genetic control

B) Covalent modification

C) Allosteric regulation

D) Compartamentation

E) All of the above are correct

Zymogens are a feature of what type of enzymatic control?

 Regulatory enzymes are a feature of what type of enzymatic control?

Positive cooperativity is a feature of what type of enzymatic control?

Segregation of biochemical pathways into different organelles in an example of which type of enzymatic regulation?

Catalysts are effective because they:

 Enzymes act by _________.

Enzyme studies are best carried out:

Alcohol dehydrogenase is an example of which of the following classes of enzymes?

Which of the following is not an assumption of the law of mass action?

A) Forward reaction is linear

B)  Reverse reaction is linear

C) System is homogenous

D)  Interacting molecules move randomly and independently of each other

E) All are assumptions of the law of mass action

Metabolons are defined as:

Metabolic flux is best defined as a:

Which of the following molecules can most easily facilitate quantum mechanical tunneling? 

A) NADH

B) NADD

C) NADT

D) All of the above are correct

E) None of these molecules are involved in tunneling

Which of the following amino acids cannot actively participate in a catalytic site?

A) Serine

B) Threonine

C) Tyrosine

D) Lysine

E) Glutamine

In addition to serine and aspartate which of the following amino acids is a member of the serine triad?

Which of the following is not an important metal in biological systems

A) Na+

B) K+

C) Mg++

D) Cu++

E) Ba++

Both glycogenesis and glycogenolysis are controlled primarily by the interplay between the two hormones insulin and ________.

Hexokinase D is found in the _______.

An enzyme family called the _________ catalyzes the phosphorylation of hexoses in the body.

The conversion of glucose-1-phosphate to UDP-glucose has a DG0’ near zero. Which of the following reactions is coupled with the above reaction to drive it to completion?

Which of the following is required for the conversion of UDP-glucose to glycogen?

A) Glycogen synthase

B) Branching enzyme

C) Glucose phosphorlyase

D) Debranching enzyme

E) Both A and B are correct

A glycogen molecule that has been degraded to its branch points is called

Regulation of glycolysis involves all of the following except

A) Insulin

B) Glucagon

C) SREBP1c

D) AMPK

E) None of the above

The binding of insulin to receptors on the surface of muscle cells stimulates which of the following processes

Under stressful conditions epinephrine is released from the adrenal medulla. The release of epinephrine has which of the following effects on glucose metabolism?

A) Glycogenolysis is stimulated

B) Glycogenesis is inhibited

C) Adenylate cyclase is activated

D) Both A and B are correct

E) All of the above are correct

Phosphorylase kinase

Cori’s disease is caused by

Which of the following activates phosphoprotein phosphatase?

Glucose-6-phosphate is a substrate in which of the following processes

A) Gluconeogenesis

B) Glycolysis

C) Photosynthesis

D) Glycogenolysis

E) Both A and B are correct

Fructose-2,6-biphosphate

The Embden-Myerhof pathway is also referred to as

In glycolysis ________ moles of ATP are produced per mole of glucose consumed.

In glycolysis ________ moles of NADH are produced per mole of glucose consumed

The presence of which of the following molecules indicates that the cell has sufficient energy reserves?

A) ATP

B) Citrate

C) ADP

D) Fructose-1,6-biphosphate

E) Both A and B are correct

Which of the following enzymes is an oxidoreductase?

The first reaction in the oxidative phase of the pentose phosphate pathway is catalyzed by

Which of the following enzymes catalyzes an irreversible process

In anaerobic organisms pyruvate is used to regenerate cellular ________

Allosteric regulation of which of the following enzymes is important in the regulation of glycolysis?

A) Hexokinase

B) PFK-1

C) Pyruvate kinase

D) Both A and C are correct

E) All of the above are correct

Gluconeogenesis occurs primarily in the

) Which of the following molecules can be used to synthesize glucose via gluconeogenesis.

A)  Lactate

B) Pyruvate

C) Glycerol

D) Keto acids

E) All of the above are correct

Which of the following is the most important glucogenic amino acid?

A) Aspartate

B) Alanine

C) Glycine

D) Glutamate

E) All are equally important

Gluconeogenesis is stimulated by high concentrations of which of the following compounds?

A) Lactate

B) Glycerol

C) Amino acid

D) Both A and B are correct

E) All of the above are correct

Which of the following is an oxidizing agent in fermentation?

A) Lactate

B) Glucose

C) NADH

D) Pyruvate

E) ADP

In addition to glucose which of the following sugars are important in the human diet?

A) Fructose

B) Galactose

C) Mannose

D) Sucrose

E) Both A and D are correct

Intermediates in the nonoxidative phase of the pentose phosphate pathway include all of the following except

A) Dihydroxyacetone phosphate

B) Sedoheptulose-7-phosphate

C) Fructose-6-phosphate

D) Xylulose-5-phosphate

E) Erythrose-4-phosphate

The use of a highly exergonic reaction in the beginning of a catabolic pathway is referred to as 

Aldol cleavage of which of the following sugars will produce one mole each of dihydroxyacetone and glyceraldehyde?

Which of the following is a second messenger in glycogenolysis?

A) Glucagon

B)  Insulin

C)  Glucose

D)  ATP

E) cAMP

Phosphoroylation of glucose upon entering the cell has what effect?

Physiologically, the most important kinases are  glycogen kinase and  ________

Which of the following enzymes is not required in gluconeogenesis?

A) Phosphoenolpyruvate carboxekinase

B)  Phosphofructokinase

C)  Pyruvate kinase

D) Fructose-1,6-bisphosphatase

E)  Pyruvate carboxylase

The final product of glycolysis is

The principal products of the pentose phosphate pathway include

Flux of which of the following sugars into the glycolytic pathway is essentially unregulated.

A) Glucose

B) Fructose

C) Glucose-1-phosphate

D) Both A and C are correct

E) None of the above are correct

Conversion of fructose-6-phosphate to fructose-1,6-bisphosphate has two purposes. One is the commitment of the molecule to glycolysis, the second is

Enzymes act by _________.

In the graph reaction rate vs substrate concentration, the reason that the curve reaches a plateau, and does not increase any further at high substrate concentration is that:

Regulatory enzymes are a feature of what type of enzymatic control?

Zymogens are a feature of what type of enzymatic control?

Enzyme control is accomplished in which of the following ways?

NADPH and NADH are coenzymes found in which class of enzymes?

Which of the following amino acids can participate in covalent catalysis?

A) Tryptophan;  B) Tyrosine;  C) Serine;  D) Histidine;  E) Both C and D are correct

Which of the following is the abbreviated formula of the tetrapeptide shown below? (Hint: remember to start at the N-terminal end.)

 

Which of the following classes of enzymes catalyze reactions involving the cleavage of bonds by the addition of water?

The expression of the Michaelis constant is equal to:

The lock and key model of enzyme activity proposes that each:

Which of the following structures is the beta-anomer of D-glucose:

The structures below can be identified as:

The figure below shows which type of chemical reaction:

The figure below shows a redox reaction used to identify glucose.  In this reaction:

Which one of the following is not true concerning D-glucose? 

A.     D-glucose is a reducing sugar; 

B.     D-glucose readily forms cyclic hemiacetals.; 

C.    D-glucose is optically active;      

 D.   D-glucose is a ketose.

The alpha and beta forms of D-glucopyranose can be described as  

The first step in glycolysis is phosphorylation of glucose to form glucose-6-phosphate. This action serves to:

The end product of glycolysis under anaerobic conditions is:

Which of the following decreases the rate of glycolysis in a tissue?

An enzyme family called the _________ catalyzes the phosphorylation of hexoses in the body.

Under stressful conditions epinephrine is released from the adrenal medulla. The release of epinephrine has which of the following effects on glucose metabolism?

A) Glycogenolysis is stimulated; 

B) Glycogenesis is inhibited; 

C) Adenylate cyclase is activated

D) Both A and B are correct; 

E) All of the above are correct

One of the early steps in glycogenesis is formation of UDP-glucose from glucose-1-phosphate and UTP according to the reaction:

Glucose-1-phosphate + UTP → UDP-glucose + PPi

One would expect this reaction to occur spontaneously if ΔG° were large and negative, but in fact, ΔG° for this reaction is nearly zero. What, then, drives the reaction?

We consume some fructose in our diet. The fructose can provide energy by:

The principal products of the pentose phosphate pathway include

During metabolism in a certain tissue, glucose is oxidized, ATP is generated, and NAD + is reduced to NADH. At the same time, CO 2 is released. The most likely type of metabolism here is:

Gluconeogenesis is stimulated by high concentrations of which of the following compounds?

A) Lactate; 

B) Glycerol; 

C) Amino acid; 

D) Both A and B are correct;

E) All of the above are correct

Allosteric regulation of which of the following enzymes is important in the regulation of glycolysis?

A) Hexokinase;   

B) PFK-1; 

C) Pyruvate kinase; 

D) Both A and C are correct; 

E) All of the above are correct

The presence of which of the following molecules indicates that the cell has sufficient energy reserves?

A) ATP; 

B) Citrate; 

C) ADP; 

D) Fructose-1,6-biphosphate; 

E) Both A and B are correct

The end product of glycolysis under anaerobic conditions is:

 Phosphofructokinase is allosterically inhibited by high concentrations of

The process by which ATP is formed from ADP in glycolysis is referred to as

In glycolysis ________ moles of ATP are produced per mole of glucose consumed.

Which of the following molecules can be used to synthesize glucose via gluconeogenesis.

A)  Lactate; 

B) Pyruvate; 

C) Glycerol; 

D) Keto acids; 

E) All of the above are correct

Which of the following is the most important glucogenic amino acid?

In the figure below the glucose-alanine cycle is shown.  In this cycle the alanine is derived in the muscle from the …..…….amino acid  by a …………reaction.

In the degradative pathway major nutrients are _________ broken down, resulting in the synthesis of __________ .

Conversion of galactose to glucose is accomplished by a(n)

Which of the following statements about glycogen is false?

A) Glycogen is a polymer of glucose in (14) linkages with (16) linked branches every 8–14 residues.

B) Glycogen is the storage polysaccharide in skeletal muscle and liver cells.
C) UDP–glucose is produced from glycogen by the action of the enzyme phosphorylase.
D) In glycogen breakdown, glucose residues are sequentially removed from the nonreducing ends.

In which cellular location does the following reaction take place?

pyruvate + HCO3- + ATP  ® oxaloacetate + ADP + Pi

In glycolysis ________ moles of NADH are produced per mole of glucose consumed

In the figure below identify the enzymes catalyzing the specific reactions:

What are the coenzyme forms that correspond to X and Y in the following gluconeogenic reaction catalyzed by glyceraldehyde-3-phosphate dehydrogenase?

Acyl phosphates such as 1,3-bisphosphoglycerate have a ______ phosphoryl group transfer potential compared to ATP, which can be recognized by the _______ deltaG°' values for hydrolysis.

The ubiquitous chemistry of acetyl-CoA is centered on its high-energy _________________ bond.

Which of the following is (are) associated with cAMP binding to cAMP-dependent protein kinase A?

A)cAMP binds to the regulatory subunits

B) regulatory subunits dissociate from catalytic subunits

C) catalytic subunits phosphorylate multiple targets with specifc serines and threonines

D) A and B

E) A, B, and C

In liver cells, if cAMP concentrations are high

Which of the following enzymes converts phosphorylase b is to the more active phosphorylase a?

A)cAMP-dependent protein kinase;  

B) phosphorylase kinase

C)glycogenin; 

D)calmodulin

E) phosphoprotein phosphatase-1

Which of the following serves as the free energy sourcefor the metabolic conversion of oxaloacetate to phosphoenolpyruvate, which is catalyzed by PEP carboxykinase?

A) hydrolysis of ATP —> ADP + Pi; 

B) hydrolysis of ATP —> AMP + PPi —> 2Pi

C)hydrolysis of GTP —> GDP + Pi;

D)hydrolysis of an internal phosphoanhydride

Muscle cells are not able to supply glucose for other tissues because they do not contain which of the following enzymes?

A) debranching enzyme; B) pyruvate carboxylase; C) glucose-6-phosphatase
phosphoglucomutase;  E) glycogen phosphorylase

The reaction below is catalyzed by:

Which of the following best describes the citric acid cycle as a central pathway of metabolism?

A) It is important for recovery of energy from carbohydrates only.
B) It is important for recovery of energy from fatty acids only.
C) It is important for recovery of energy from amino acids only.
D) It is important for recovery of energy from several metabolic fuels that are broken down to acetyl-CoA.
E) Only A) and B) above

The reduced coenzymes of the TCA cycle, such as FADH 2 and NADH, must pass their electrons into the electron transport chain to produce ATP, but one step of the TCA cycle yields a compound with high transfer potential that can provide energy for phosphorylation of ADP at the substrate level. What is this high-energy compound?

You may have learned the term B amphoteric B used in general chemistry to describe a substance that could function as either an acid or a base. When we describe the TCA cycle as amphibolic, we mean that it:

In addition to the regulators of enzyme activity within the citric acid cycle, two enzymes outside the cycle profoundly affect its activity. Which ones?

Which of the following citric acid cycle intermediates can be converted to aspartate via transamination?

A)Citrate; 

B)alpha-ketoglutarate;

C)succinate;

D) fumarate;

E)oxaloacetate

Which of the following conversions is an anaplerotic reaction of the citric acid cycle?

A) Pyruvate to oxaloacetate;

B) Ceretain amino acids to succinyl CoA;

C) Glutamate to alpha-ketoglutarate;

D) Aspartate to oxaloacetate;

E) All of the above are correct

NADH and NADPH are major coenzymes for oxidoreductases. While nearly equivalent in redox potential, the two coenzymes often function in different metabolic actions. In general:

Formation of ATP is increased by

If not otherwise dangerous, uncouplers would make good diet aids because:

Formation of ATP as a result of passage of electrons through the ETC is sometimes called oxidative phosphorylation because:

Among the important antioxidant molecules taken in with our food are:

Mitchell's chemiosmotic theory suggested that a high concentration of protons outside the mitochondrial membrane:

Branched-chain fatty acids, such as phytanic acid, are not a lost cause as sources of energy. They may be broken down by a process with begins with:

The location of fatty acid oxidation is:

Drugs called statins are now used to decrease plasma cholesterol levels by inhibiting the rate-limiting step of cholesterol synthesis. This step is catalyzed by:

Fatty acid oxidation occurs mostly within mitochondria, but fatty acids themselves canB t easily cross the mitochondrial membrane. How do they pass?

Fatty acid synthesis is dependent upon aggregation of dimers of acetyl-Co carboxylase to form polymers. This aggregation is slowed or prevented by:

Which of the following statements about the transport of fatty acyl-CoA derivatives (activated fatty acids) into the mitochondria is correct?

The dietary fats are transported as

Which statement best describes the oxidation of odd chain fatty acids?

a)   Additional specific enzymes are needed for the oxidative process

b)   One carbon is removed in one cycle

c)   End product is propionyl co A

d)   Hydroxy fatty acids are produced

The key regulatory enzyme of fatty acid synthesis is-

Malonyl co A is a direct inhibitor of which enzyme of fatty acid oxidation?

Which out of the followings is the primary ketone body?

a)   Acetone

b)   Acetoacetate

c)   Beta-hydroxy butyrate

d)   Hydroxy Methyl glutarate

The key regulatory enzyme of cholesterol synthesis is-

Which of the following statements about triacylglycerols is correct?

Which of the following statements about the activation of fatty acids is correct?

Which of the following statements about the transport of fatty acyl-CoA derivatives (activated fatty acids) into the mitochondria is correct?

a) Only the acyl groups of fatty acyl-CoA derivatives are attached to carnitine.

b) Fatty acyl-CoA derivatives can diffuse into the mitochondrial matrix because they are hydrophobic.

c) Fatty acyl-CoAs are carried into the mitochondrial matrix by a carnitine shuttle.

d) Fatty acyl-CoAs are oxidised in the mitochondrial matrix because most of the ATP generated is needed there.

The ETC component that transfers electrons directly to oxygen is __________.

During the oxidation of NADH there are several steps in which  deltaEo’  is sufficient for ATP synthesis. These occur within

ATP synthesis and mitochondrial electron transport are coupled by

In Complex I of the ETC, the major sources of NADH include

In Complex III, electrons are tranferred from UQH2 to

The final product of oxidative phosphorylation is ________.

The return of ______ into the mitochondrion is coupled to the formation of ______.

The energy that is captured by the electron transport system is in the form of

The cytochromes contain which type of prosthetic group?

The function of complex III is the transfer of electrons from

How many ATP are generated during the oxidation of one NADH?

How many ATP are generated during the oxidation of one FADH2?

Which of the following are true statements about the structure of ATP synthase?

A)It has a membrane-embedded component called F0 and a component found in the matrix referred to as F1;

B) The g subunit acts as a “cam” shaft in the rotational motor; 

C) The structure has a “lollipop” shape

D) A and B;

E)A, B, and C

Which of the following energy sources drives the phosphate carrier that transports P_i into the mitochondria from the cytosol?

A)ATP hydrolysis

B)simultaneous transport of H+ into the mitochondrion;  C)simultaneous transport of ADP into the mitochondrion;  D)simultaneous transport of H+ out of the mitochondrion;  E)simultaneous transport of ATP out of the mitochondrion

Which of the following statements are true about oxidative phosphorylation?

A)Electron transport provides energy to pump protons into the intermembrane space.

B)An electrochemical gradient is formed across the inner mitochondrial membrane.

C) Potassium and sodium ions form an ionic gradient across the inner mitochondrial membrane.

D) A and B; 

E) A, B, and C

Recognize the structures below and choose the best answer for the indicated labels:

The overall reaction catalyzed by pyruvate dehydrogenase is which of the following?

A) CH3COCHO  + NAD⁺ + CoASH →CH3CHOSCoA + NADH

B) CH3COCOO^- + FAD +CoASH →CH3CHSCoA  + NADH

C) CH3COCOO^- + NAD+ + CoASH →CH3COSCoA + NADH

D) CH3CH(OH)COO^- + NADH + CoASH → CH3CH(OH)COSCoA + NAD⁺

Which statement concerning Complex II of the electron transport chain is false?

A) This complex oxidizes FADH2 and reduces coenzyme Q.;

B) This complex includes a cytochrome heme.; 

C)This complex includes Fe-S centers;

D) This complex pumps protons from the matrix to the intermembrane space;

E)This complex also oxidizes succinate to fumarate in the TCA cycle.

Which is the enzyme catalyzing the two steps reaction below and which is the metabolic pathway in which this reaction occurs?!

Some chemical reactions catalyzed by the multifunctional fatty acid synthase are shown below.Identify the enzymes that catalyze each of the indicated steps:

During starvation, DHAP used to synthesize triacylglycerols is provided by a simplified version of gluconeogenesis called

Cholesterol is a precursor to:

The _____ are synthesized from C20 fatty acids such as ______ and trigger pain and inflammation.

Which of the following citric acid cycle intermediates can be converted to aspartate via transamination?

Place the following reaction intermediates of the citric acid cycle in chronological order. i. malate,  ii fumarate, iii succinylCoA, iv citrate, v α-ketoglutarate.

FADH2 is a product of which of the following reactions?

Acetyl CoA that is consumed by the citric acid cycle is produced from which of the following biochemical pathways?

The carbon skeletons of which of the following are direct precursors of amino acids? 

The overall reaction catalyzed by pyruvate dehydrogenase is which of the following?

The citric acid cycle is a component of aerobic respiration. Molecular oxygen

The main toxic effect of oxygen is due to which of the following?

The first molecule of carbon dioxide is released from which of the following compounds in the citric acid cycle?

The high energy molecule produced in the conversion of succinyl-CoA to succinate is which of the following

Which of the following conversions is an anaplerotic reaction of the citric acid cycle?

A) Pyruvate to oxaloacetate

B) Ceretain amino acids to succinyl CoA

C) Glutamate to a-ketoglutarate

D) Aspartate to oxaloacetate

E) All of the above are correct