Glycolysis/Gluconeogenesis

Glycolysis

"sweet splitting"

Gluconeogenesis produces:

1GLC + 4ADP + 2GDP + 6Pi + 2H+

. How many net moles of ATP would be formed in the glycolytic conversion of one mole of fructose 1, 6-bisphosphate into phosphoenolpyruvate?

2

Glycolysis produces how much ATP (net) from each glucose that enters the pathway?

2 ATPS Net

An allosteric inhibitor of phosphofructokinase-1 is: a. ATP b. AMP c. ADP d. Fructose 2,6-bisphosphate e. Glucose-6-phosphate

A

What is the net yield of NADH when glucose-6-phosphate is oxidized by anaerobic glycolysis to yield lactate? a. 0 b. 1 c. 2 d. 3 e. 4

A

Which of the following catalyzes a dehydration (loss of H2O) reaction: a. enolase b. aldolase c. phosphoglycerate kinase d. pyruvate decarboxylase e. pyruvate kinase

A

Which of the following is a positive allosteric effector of phosphofructokinase?

AMP

PFK stimulated by

AMP lvls

Pyruvate kinase inhibited by

ATP and Alanine

. Fructose 2,6 bisphosphate: a. Is made from fructose-6-phosphate in a reaction catalyzed by glucokinase b. Is made from fructose-6-phosphate in a reaction catalyzed by a special phosphofructokinase (PFK-2) found in the liver. c. Is an allosteric activator of fructose 1,6- bisphosphatase d. Is an allosteric activator of pyruvate kinase e. Is an allosteric activator of hexokinase.

B

. Regulated steps of glycolysis in muscle tissue include which of the following (pick answer from a. b ,c, d, e below): 1. The phosphoglycerate mutase reaction 2. The phosphofructokinase reaction 3. The enolase reaction 4. The glyceraldehyde-3-phosphate dehydrogenase reaction 5. The pyruvate kinase reaction

B

. The substrates for the phosphoenolpyruvate carboxykinase reaction are: a. Alanine and GTP b. oxaloacetate and GTP c. oxaloacetate and ATP d. phosphoenolpyruvate and GTP e. Pyruvate and ATP

B

In glycolysis, a. one mole of ATP is generated in the conversion of glucose to glucose-6- phosphate. b. ATP is generated in both the conversion of phosphoenolpyruvate to pyruvate, and the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate. c. One mole of ATP is consumed in the conversion by aldolase of fructose 6- phosphate to fructose 1,6-bisphosphate. d. NADH is produced by the reaction catalyzed by pyruvate enolase. e. Both ' a' and 'c' are true.

B

Which of the following statements about pyruvate is FALSE? a. Pyruvate can enter the Citric Acid Cycle under aerobic conditions b. Pyruvate is metabolized to glucose when blood glucose levels are high. c. Pyruvate can be metabolized to lactate under anaerobic conditions. d. Pyruvate can be metabolized to ethanol under anaerobic conditions. e. Mitochondrial pyruvate is converted to oxaloacetate in gluconeogenesis

B

Citrate regulates which enzymes: a. Pyruvate carboxylase and pyruvate kinase b. Hexokinase and phosphoenolpyruvate carboxykinase c. Phosphofructokinase and fructose 1,6-bisphosphatase d. Pyruvate kinase and phosphofructokinase e. Pyruvate carboxylase and glyceraldehyde-3-phosphate dehydrogenase

C

Which of the following compounds is an allosteric activator of pyruvate carboxylase? a. citrate b. ADP c. acetyl Co A d. AMP e. Fructose 1,6 biosphosphate

C (ADP is the inhibitor)

. Reactions common to both the breakdown and the biosynthesis of glucose are catalyzed by:a. Aldolase and Pyruvate Carboxylase b. Phosphoglycerate Kinase and Phosphoenolpyruvate Carboxykinase c. Triose Phosphate Isomerase and Hexokinase d. Glyceraldehyde -3 Phosphate Dehydrogenase and Enolase e. Fructose 1,6 bisphosphatase and Glucose 6 Phosphatase

D

All of the following statements about glucose-6-phosphate are true EXCEPT: a. Its production from glucose in the liver is catalyzed by glucokinase and in the muscle by hexokinase. b. The compound normally does not cross cell membranes. c. High concentrations of it inhibit hexokinase. d. It activates pyruvate kinase by feed-forward activation e. It is converted to fructose-6-phosphate by phosphoglucose isomerase

D

All of the following statements about the enzyme glyceraldehyde-3-phosphate dehydrogenase are correct EXCEPT: a. it catalyzes an oxidation/reduction reaction. b. the enzyme forms a compound with that can donate a phosphoryl group to ADP. c. NAD+ is reduced d. Substrate level phosphorylation occurs in the reaction it catalyzes. e. inorganic phosphate is used in the reaction

D

Release of the hormone glucagon a. Stimulates gluconeogenesis b. Stimulates glycolysis c. Occurs when blood glucose levels fall d. Occurs most commonly after a big meal e. a & c are both correct

E

The gluconeogenesis pathway:a. produces glucose from precursors like dihydroxyacetone phosphate and pyruvate. b. provides a means for the further metabolism of lactate c. occurs partly in the mitochondria when pyruvate is involved. d. is a pathway that consumes ATP, but does not generate it. e. all of the above

E

. The Cori cycle converts pyruvate to ethanol under some circumstances (T/F)

F

Fructose can enter glycolysis by conversion to fructose-6-phosphate, followed by an aldolase reaction to give glycerol and dihydroxyacetone phosphate. (T/F)

F

Pyruvate Kinase stimulated by

F 1,6 BP

Deficiency in phosphoglucomutase results in a disease called galactosemia (T/F)

F, Deficiency in gal-1-P-uridyl transferase

What enzymes are different in glycolysis?

Glc-6 phosphatase (hexokinase) F1,6 bptase (PFK), pyruvate carboxylase (pyruvate kinase), PEP carboxykinase

Liver irreversible enzymes

Hexokinase (or glucokinase), PFK-1, Pyruvate kinase-l

Which enzymes consume ATP

Hexokinase, PFK,

Muscle irreversible enzymes

Hexokinase, PFK-1, Pyruvate Kinase-m

Insulin induces expression of,

PFK-1, PFK-2, PK

What is glycolysis the main source of energy for?

RBC Renal medula brain sperm

The Cori cycle occurs partially in the liver (T/F)

T

The Cori cycle ships muscle lactate to the liver for conversion to glucose (T/F)

T

During glycolysis carried out under anaerobic conditions, pyruvate can undergo fermentation to lactate or ethanol. (T/F)

TRUE

Which of the following glycolytic reactions is/are not reversible? Glucose-6-phosphate à Fructose-6-phosphate b. Fructose 1,6-bisphosphate à dihydroxyacetone phosphate + glyceraldehyde 3- phosphate c. Dihydroxyacetone phosphate à glyceraldehyde 3-phosphate d. Fructose 6-phosphate à fructose-1,6-bisphosphate e. All of the above.

a. Reversible b. reversible c. reversible d. not reversible

glucagon activates, induces expression of, and inhibits expression of

activates PKA, induces expression of : PEP carboxykinase, F1,6 bp inhibits: hexokinase, PFK-1,

What enzyme is used for ethanol formation?

alcohol dehydrogenase (acetaldehyde => ethanol)

fermentation

an aerobic degradation of glucose

Why doesn't pyruvate get pushed into gluconeogenesis right after it is made?

because gluconeogenesis is in the mito and glycolysis is in the cytosol

How is NAD+ regenerated?

by metabolism of pyruvate

Cori cycle

circular pathway in which lactic acid produced by glycolysis in skeletal muscle is carried to liver cells, where it si back to converted back to glucose and stored as liver glycogen

biotin

cofactor to the transfer of CO2 in carboxylation rxns. pyruvate carboxylase ( pyruvate => ooa)

Where does glycolysis occur?

cytosol

lactose intolerance

deficiency in lactase

How is NAD+ regenerated in anaerobic conditions?

ethanol formation, lactate formation

Where does glucose act as a structural component?

extracellular matrix, cell wall,

PFK inhibited by

high ATP lvls, and low pH

respiration level phosphorylation

involves membrane bound enzymes and transmembrane proton gradients

substrate level phosphorylation

involves soluble enzymes and chemical intermediates, Transfer of a phosphate group from an organic compound to ADP. Glycolysis and citric acid cycle utilize substrate level phosphorylation to produce ATP.

What enzyme is used in lactate formation?

lactate dehydrogenase (pyruvate => lactate)

Type 1 diabetes

little insulin (hyperglycemia), cellular Glc is low in muscles

Where does gluconeogenesis occur

liver kidney cytosol

hypoxia

low CO2 HIF (hypoxia induced transcription factor) allows for cancers to survive

pyruvate carboxylase

makes OAA from pyruvate in mitochondrial matrix; allosterically activated by acetylCoA

in cytosol NAD-linked oxidizes:

malate to ooa

in mito NADH-linked reduces:

ooa to malate

What is the purpose of shipping lactate to the heart?

oxygen rich area can carry out aerobic respiration

Which glycolytic enzyme catalyzes the isomerization of an aldose to a ketose?

phosphoglucose isomerase

Which enzymes make ATP

phosphoglycerate kinase, pyruvate kinase

What can prevent the conversion of pyruvate to ooa?

presence of ADP (signals low energy)

What enzyme is used for converting pyruvate to oxaloacetate?

pyruvate carboxylase

Importance of phosphorylated intermediates

retains intermediates in the cell, conserves metabolic energy, binding energy from binding of phosphate groups to active sites to lower activation energy and increase specificity

Glucose

rich in potential energy, can be stored as glycogen or starch, can be metabolized aerobically or anaerobically

What is the purpose of shipping lactate to the Liver

so it can be pushed back through gluconeogenesis (lactate => pyruvate => Glc => back to muscle with cori cycle)

What type of phosphorylation does glycolysis use?

substrate level phosphorylation