Tutorial 1

Question 1

What part of the cell contains the enzymes that perform glycolysis?

Answer 1

Cytosol

Question 2

Fill in the blanks:
In the glycolytic pathway, one molecule of the 6-carbon compound _______ , is converted into 2 molecules of the 3-carbon compound _______.

Answer 2

1. Glucose
2. Pyruvate

Question 3

Before glycolysis can occur…glucose must be trapped inside the cell. Explain how this is achieved

Answer 3

Glucose is phosphorylated to glucose 6-phosphate, by the enzyme hexokinase

Question 4

Name at least 2 glycolytic reactions that involve phosphoryl transfers.

Answer 4

1. Hexokinase
2. Phosphofructokinase
3. Phosphoglycerate Kinase
4. Pyruvate Kinase

Question 5

Name one glycolytic reaction that is an example of substrate level phosphorylation

Answer 5

Glyceraldehyde 3-Posphate Dehydrogenase

Question 6

Glyceraldehyde 3-phosphate is oxidised during glycolysis.
Choose the option below which best explains what happens to the hydrogen atom and the electron that are removed during oxidation.

a. They reduce NAD+
b. They oxidise NAD+
c. They are transferred to ATP
d. They are eliminated as methane

Answer 6

A. They reduce NAD+

Question 7

In the presence of oxygen, how many molecules of ATP can be synthesised by glycolysis, from one molecule of glucose.

Answer 7

4 ATP and 2 NADH

Question 8

MULTIPLE CHOICE

Glycolysis is a pathway which occurs in:
a. Eukaryotic cells only
b. Prokaryotic cells only
c. Most muscle cells
d. Virtually all cells

Answer 8

d. Virtually all cells

Question 9

What part of the cell contains the enzymes that perform the citrate cycle?

Answer 9

Mitochondrial matrix

Question 10

How many carbon atoms are in an oxaloacetate molecule, which joins with an acetyl group during the first reaction in the citrate cycle?

A. 2
B. 3
C. 4
D. 6

Answer 10

C. 4

Question 11

How many carbon atoms are in a citrate molecule?
a. 2
b. 3
c. 4
d. 6

Answer 11

D. 6

Question 12

Fill in the blanks:
Oxidative decarboxylation which occurs during steps 3 and 4 of the citrate cycle, is the removal of both_________and __________from a substrate at the same time.

Answer 12

1. Hydrogen
2. Carbon dioxide

Question 13

Which one of the following statements concerning the citric acid cycle is correct?

A. The cycle produces 3 moles of NADH and 1 mole of FADH2 per mole of acetyl CoA oxidised to CO2 and H2O.
B. The cycle is inhibited by malate.
C. Elevated levels of NADH stimulate oxidation of acetyl CoA by the cycle.
D. The oxidation of acetate leads to a net consumption (loss) of oxaloacetate.
E. The conversion of one mole of isocitrate to one mole of succinate results in the formation of five moles of ATP (including those obtained form oxidative phosphorylation

 

Answer 13

A. The cycle produces 3 moles of NADH and 1 mole of FADH2 per mole of acetyl CoA oxidised to CO2 and H2O

Question 14

Which one of the following is NOT a characteristic of gluconeogenesis?

a. It requires energy in the form of ATP or GTP.
b. It is important in maintaining blood glucose during the normal overnight fast.
c. It uses carbon skeletons provided by degradation of amino acids.
d. It consists of all the reactions of glycolysis functioning in the reverse direction.
e. It involves the enzyme fructose 1,6-bisphosphatase.

Answer 14

d. It consists of all the reactions of glycolysis functioning in the reverse direction

Question 15

Which one of the following reactions is unique to gluconeogenesis?

a. Lactate —> pyruvate
b. Phosphoenolpyruvate —> pyruvate
c. Oxaloacetate —> phosphoenolpyruvate
d. Glucose 6-phosphate —> fructose 6-phosphate
e. 1,3-Bisphosphoglycerate —> 3-phosphoglycerate

Answer 15

c. Oxaloacetate —> phosphoenolpyruvate

Question 16

Which one of the following compounds cannot give rise to the net synthesis of glucose?

a. Lactate
b. Glycerol
c. alpha-Ketoglutarate
d. Oxaloacetate
e. Acetyl CoA

Answer 16

e. Acetyl CoA

Question 17

Which one of the following statements concerning gluconeogenesis is correct?

a. It occurs only in muscle.
b. It is stimulated by fructose 2,6-bisphosphate
c. It is inhibited by elevated levels of acetyl CoA
d. It is important in maintaining blood glucose during the normal overnight fast.
e. It uses carbon skeletons provided by the degradation of fatty acids.

Answer 17

d. It is important in maintaining blood glucose during the normal overnight fast.

Question 18

Compared to the resting state, vigorously contracting muscle shows:

a. An increased conversion of pyruvate to lactate.
b. Decreased oxidation of pyruvate to CO2 and water
c. A decreased NADH/NAD+ ratio
d. Decreased concentration of AMP
e. Decreased levels of fructose 2,6-bisphosphate

Answer 18

a. An increased conversion of pyruvate to lactate

Question 19

Muscle glycogen cannot contribute directly to blood glucose levels because:

a. Muscle glycogen cannot be converted to glucose 6-phosphate
b. Muscle lacks glucose 6-phosphatase
c. Muscle contains no glucokinase
d. Muscle contains no glycogen phosphorylase
e. Muscle lacks phosphoglucoisomerase

Answer 19

b. Muscle lacks glucose 6-phosphatase

Question 20

An abnormal, poorly branched glycogen was isolated from the liver of a patient with type IV glycogen storage disease.

The deficiency is most probably in:
a. Phosphorylase kinase
b. Glycogen phosphorylase
c. Protein kinase A
d. Amylo-alpha-(1,6)-glucosidase
e. Amylo-alpha-(1,4—> alpha-1,6)-transglycosylase

Answer 20

e. Amylo-alpha-(1,4—> alpha-1,6)-transglycosylase

Question 21

Liver glycogen can contribute directly to blood glucose levels because:

a. Liver glycogen cannot be converted to glucose 6-phosphate
b. Liver contains glucose 6-phosphatase
c. Liver contains no glucokinase
d. Liver contains no glycogen phosphorylase
e. Liver lacks phosphoglucoisomerase

Answer 21

b. Liver contains glucose 6-phosphatase