BICH 411 Exam 1

The corresponding cofactor/intermediate of pyruvate decarboxylase is:

Thiamine pyrophosphate

The corresponding cofactor/intermediate of transketolase is:

Thiamine pyrophosphate

Match the following: Transaldolase Transketolase Phosphoglucomutase Pyruvate Carboxylase Glycogen phosphorylase Biotin Thiamine pyrophosphate Pyridoxal Phosphate Schiff Base Phosphoserine

Transaldolase --> Schiff Base Transketolase --> Thiamine pyrophosphate Phosphoglucomutase --> Phosphoserine Pyruvate Carboxylase --> Biotin Glycogen phosphorylase --> Pyridoxal Phosphate

(T/F) Glycolysis is an exergonic process

True

(T/F) Pyruvate Carboxylase is found only in the mitochondria

True

Glycogen synthesis requires __________ to activate glucose-1-phosphate.

UTP

The conversion of 3-phosphoglycerate into 2-phosphoglycerate invoves:

a phosphorylated histine residue

Isozymes:

are enzymes that catalyze the same reaction but are encoded by different genes.

Glycogen stored in the muscles cannot contribute directly to blood glucose levels because:

muscle tissue lacks glucose-6-phosphatase

Green leaf cells of plants are:

photoautotrophic

(T/F) Glycogen synthase requires pyridoxal phosphate as a cofactor.

False

(T/F) Glycolytic enzymes are found in the mitochondria

False

(T/F) One of the function of the pentose phosphate pathway is to generate NADH

False

(T/F) the first committed step of glycolysis is catalyzed by hexokinase

False

Glycolysis is an anabolic pathway (T/F)

False

Which of the following is not a substrate of Hexokinase? A. Fructose B. Glucose C. Mannose D. Galactose

Galactose

Write the balanced equation for the formation of glycogen from galactose:

Galactose + ATP + UTP + H2O + Glycogen_n --> Glycogen_n+1 + ADP + UDP + 2Pi

In terms of yield, phosphorolysis is preferable to hydrolysis in the breakdown of glycogen because:

Glucose 1-phosphate yields more net ATP then free glucose yields when catabolized into pyruvate.

In an intact cell, the free energy change (ΔG) associated with an enzyme catalyzed reaction is often different from the standard free energy change (ΔG0) of the same reaction because:

In the cell, the concentration of reactants and products are not at 1M concentrations

Which of the following enzymes catalyzes a substrate level phosphorylation? (A)Pyruvate kinase. (B) Hexokinase. (C) Phosphofructokinase. (D)Glucokinase. (E) Glucose-6-phosphatase.

(A) Pyruvate kinase

Which of the following statements about ATP is not true? (A)ATP is usually complexed with Mg2+. (B) ATP is kinetically unstable. (C) ATP has 2 phosphoanhydride bonds. (D)ATP has a large thermodynamic potential. (E) All of the above statements are true.

(B) ATP is kinetically unstable

Which of the following statements concerning catabolic pathways is true? (A) Catabolic pathways consume ATP. (B) Catabolic pathways are energy releasing. (C) Catabolic pathways are divergent. (D) Catabolic pathways are reductive. (E) All of the above statements are true.

(B) Catabolic pathways are energy releasing

Which of the following reactions is catalyzed by transaldolase? (A)Fructose-6-P + Glyceraldehyde-3-P <--> Xylulose-5-P + Erythrose-4-P (B) Erythrose-4-P + Fructose-6-P <--> sedoheptulose-7-P + Glyceraldehyde-3-P (C) Fructose-1-6-bisphosphate <--> Dihydroxyacetone-P + Glyceraldehyde-3-P (D)Sedoheptulose-7-P + glyceraldehydes-3-P <--> xyulose-5-P + ribose-5-P (E) Ribulose-5-P <--> Xyulose-5-P

(B) Erythrose-4-P + Fructose-6-P <--> sedoheptulose-7-P + Glyceraldehyde-3-P

All of the following are important reasons to phosphorylate glucose EXCEPT: (A)Glucose-6-phosphate has negative charge which prevents its transport out of the cell. (B) The large positive free energy change is important to getting the glycolytic pathway started. (C) The phosphorylation of glucose keeps the concentration of free glucose in the cell low to favor the influx of glucose into the cell. (D)The transfer of phosphoryl groups conserves metabolic energy. (E) The phosphorylation of glucose is point of regulatory control.

(B) the large positive free energy change id important to getting the glycolytic pathway started.

Which of the following reactions is unique to gluconeogenesis? (A)Pyruvate -->Lactate (B) PEP --> Pyruvate (C) Oxaloacetate --> PEP (D)Glucose-6-phosphate --> Glucose (E) 1,3-Bisphosphoglycerate --> 3-phosphoglycerate

(C) Oxaloacetate --> PEP

Which of the following statements about metabolism is incorrect? (A) All metabolic pathways are regulated. (B) Every metabolic pathway has a rate determining step (C) Every metabolic pathway has a first committed step (D) All metabolic pathways are reversible (E) Metabolic pathways may occur in different cellular locations.

(D) All metabolic pathways are reversible

Which one of the following statements concerning gluconeogenesis is correct? (A) Gluconeogenesis occurs mainly in muscle tissue. (B) Gluconeogenesis is stimulated by 2,6-bisphosphofructose. (C) Gluconeogenesis is inhibited by elevated concentrations of acetyl-CoA. (D) Gluconeogenesis is important in maintaining blood glucose levels during the overnight fast. (E) Gluconeogenesis uses fatty acids as noncarbohydrate precursors.

(D) Gluconeogenesis is important in maintaining blood glucose levels during the overnight fast

Which of the following does not contribute to the large -ΔG0' associated with ATP hydrolysis? (A)The phosphoanhydride bonds. (B) The products of hydrolysis have greater resonance stabilization that ATP. (C) The products of hydrolysis have greater solvation stabilization than ATP. (D)The entropy decreases upon ATP hydrolysis. (E) Electrostatic repulsions are relieved upon hydrolysis

(D) the entropy decreases upon ATP hydrolysis

Which one of the following statements concerning gluconeogenesis is correct? (A)Gluconeogenesis occurs mainly in muscle tissue. (B) Gluconeogenesis is stimulated by 2,6-bisphosphofructose. (C) Gluconeogenesis is inhibited by elevated concentrations of acetyl-CoA. (D)Gluconeogenesis is important in maintaining blood glucose levels during the overnight fast. (E) Gluconeogenesis uses fatty acids as noncarbohydrate precursors.

(D)Gluconeogenesis is important in maintaining blood glucose levels during the overnight fast.

Glycogen Synthase catalyzes which of the following reactions? (A)Glycogenn + Glucose --> Glycogenn+1 (B) Glycogenn + Glucose-1-phosphate --> Glycogenn+1 + Pi (C) Glycogenn+1 + Pi Glycogenn + --> a-Glucose-1-phosphate (D)Glucose-1-phosphate + UTP --> UDP-Glucose + UDP (E) UDP-Glucose + Glycogenn --> Glycogenn+1 + UDP

(E) UDP-Glucose + Glycogenn --> Glycogenn+1 + UDP

Glycogen is broken down by glycogen phosphorylase to yield glucose-1-P. If glucose-1-P passes through glycolysis to give pyruvate, the net yield is:

3 moles of ATP and 2 moles of NADH per mole of glucose-1-P

Which of the following intermediates of glycolysis are high energy compounds? A. Glucose 6-phosphate B. Fructose 1,6-bisphosphate C. Dihydroxyacetone phosphate D. 1,3-Bisphosphoglycerate

1,3-Bisphosphoglycerate

The oxidation of one molecule of glucose by anaerobic glycolysis yields a net of:

2 moles of lactate and 2 moles of ATP

Gluconeogenesis requires a total of __________ NTPs.

6

Class I aldolases are characterized by:

A Schiff base intermediate

Glucokinase: A. has a Km for glucose considerably greater than the normal blood glucose concentration B. is found in the muscle tissue C. is inhibited by glucose-6-phosphate D. is an isozyme of phosphofructokinase is metabolically important only when glucose concentration is low

A. has a Km for glucose considerably greater than the normal blood glucose concentration

Lactate produced by anaerobic muscle tissue is: a. stored in muscle until oxygen is available. b. carried by the blood to the liver for gluconeogenesis and converted to glucose. c. further reduced to glycerol in muscle. d. transferred to erythrocytes to release oxygen from hemoglobin. e. none of the above.

B. carried by the blood to the liver for gluconeogenesis and converted to glucose

The corresponding cofactor/intermediate of pyruvate carboxylase is:

Biotin

Which of the enzymes listed below is used in both gluconeogenic and glycolytic pathways? A. Hexokinase B. Phosphofructokinase-1 C. Phosphoglycerate kinase D. Pyruvate kinase E. Phosphoenolpyruvate caarboxykinase

C. Phosphoglycerate kinase

What are the final products of aerobic catabolism of glucose?

CO2 and H2O

Which of the following reactions is catalyzed by transketolase? (A)Ribulose-5-P <--> Ribose-5-P (B) Erythrose-4-P + Fructose-6-P <--> sedoheptulose-7-P + Glyceraldehyde-3-P (C) Fructose-1-6-bisphosphate <--> Dihydroxyacetone-P + Glyceraldehyde-3-P (D)Sedoheptulose-7-P + glyceraldehyde-3-P <--> xyulose-5-P + ribose-5-P (E) Ribulose-5-P <--> Xyulose-5-P

D) Sedoheptulose-7-P + glyceraldehyde-3-P <--> xyulose-5-P + ribose-5-P

The 9th reaction of glycolysis is catalyzed by:

Enolase

The extracellular "first messenger" that initiates the cyclic AMP dependent phosphorylation cascade in the muscles is:

Epinephrine

The corresponding cofactor/intermediate of alcohol dehydrogenase is:

NAD+/NADH

The corresponding cofactor/intermediate of glyceraldehyde-3-phosphate dehydrogenase is:

NAD+/NADH

Which of the following enzymes catalyze an irreversible reaction? A. Phosphoglucose isomerase B. Phosphofructokinase-1 C. Aldolase D. Glyceraldehyde-3-phosphate dehydrogenase E. Phosphoglycerate kinase

Phosphoglucose isomerase

The first committed step of glycolysis is catalyzed by:

Phosphoglycerate kinase

The corresponding cofactor/intermediate of glycogen phosphorylase is:

Pyridoxal phosphate

The last reaction of glycolysis is catalyzed by:

Pyruvate Kinase

Under anaerobic conditions, skeletal muscle generates lactate from pyruvate to:

Regenerate NAD+ for further glycolysis

The corresponding cofactor/intermediate of Class I aldolase is:

Schiff base

The corresponding cofactor/intermediate of Transaldolase is:

Schiff base

Transketolase is an enzyme that catalyzes:

The Thiamine pyrophosphate (TPP) dependent transfer of 2-carbon units to an aldolase.

Anabolism:

The biosynthesis of biomolecules from simple precursors.

Which of the following enzymes catalyzes a substrate level phosphorylation? a. phosphoglycerate kinase b. hexokinase c. phosphofructokinase d. glucokinase e. glyceraldehyde-3-phosphate dehydrogenase

a. phosphoglycerate kinase

2ADP <--> ATP + AMP is catalyzed by:

adenylate kinase

the conversion of dihydroxyacetone phosphate into glyceraldehye 3-phosphate involves:

an enediol intermediate

The mechanism of the epimerization of ribulose-5-phosphate into xylulose-5-phosphate by the enzyme ribulose-5-phosphate epimerase involves:

an enediolate intermediate

Which of the following is not a major source of energy in the cell? a. proteins b. nucleic acids c. triaglycerols d. fatty acids e. polysaccharides

b. nucleic acids

A bond may be "high energy" for any of the following reasons except: a. products of its cleavage are more resonance stabilized than the original compound b. the bond is unusually stable, requiring a large energy input to cleave it c. electrostatic repulsion is relieved when the bond is cleaved d. a cleavage product may be unstable, tautomerizing to a more stable form e. the bond may be strained

b. the bond is usually unstable, requiring a large energy input to cleave it

The enzyme fructose-1,6-bisphosphate is activated by:

citrate

The pentose phosphate pathway: a. produces NADH for the conversion of lactate to pyruvate b. produces NADH for ATP production via oxidative phosphorylation c. produces NADH for anabolic reductive biosynthesis d. produces NADPH for anabolic reductive biosynthesis e. produces NADPH for ATP production via oxidative phosphorylation

d. produces NADPH for anabolic reductive biosynthesis

The phosphorylation of glycogen synthase and glycogen phosphorylase:

deactivates glycogen synthase while activating glycogen phosphorylase

Gluconeogenesis is the synthesis of:

glucose from non-carbohydrate precursors

The endoplasmic reticulum bound enzyme that hydrolyzes glucose-6-phosphate to glucose in the liver is:

glucose-6-phosphatase

The three irreversible steps of glycolysis are catalyzed by:

hexokinase, phosphofructokinase-1, pyruvate kinase

The best control point for regulating a metabolic pathway is an enzyme that catalyzes a reaction:

that is irreversible under cellular conditions

Enolase catalyzes which reaction

the dehydration of 2-phosphoglycerate

The conversion of glyceraldehyde 3-phosphate into 1,3-bisphosphoglycerate involves:

the formation of a covalent thioester intermediate

The reaction catalyzed by glyceraldehyde-3-phosphate dehydrogenase involves:

the formation of a covalent thioester intermediate

Gluconeogeneis is:

the formation of glucose from noncarbohydrate precursors

Catabolism:

the process by which nutrients are broken down to salvage components and generate energy