Chapter 16

Question 1

Why is glucose used as a fuel by all organisms?

Answer 1

because it is the most stable hexose sugar, it is formed under prebiotic conditions, low tendency to nonenzymatically react with proteins

Question 2

hexokinase

Answer 2

phosphorylates glucose

Question 3

phosphoglucose isomerase

Answer 3

Converts glucose 6-phosphate into fructose 6-phosphate

Question 4

phosphofructokinase

Answer 4

Forms fructose 1,6-bisphosphate

Question 5

aldolase

Answer 5

cleaves fructose 1,6-biphosphate

Question 6

triose phosphate isomerase

Answer 6

Catalyzes the interconversion of three-carbon isomers

Question 7

Glyceraldehyde 3-phosphate dehydrogenase

Answer 7

Generates the first high-phosphoryl-transfer-potential compound that is not ATP

Question 8

phosphoglycerate kinase

Answer 8

generates the first molecule of ATP

Question 9

Phosphoglycerate mutase

Answer 9

Converts 3-phosphoglycerate into 2-phosphoglycerate

Question 10

enolase

Answer 10

Generates the second high-phosphoryl-transfer-potential compound that is not ATP

Question 11

pyruvate kinase

Answer 11

Generates the second molecule of ATP

Question 12

Lactic acid fermentation and alcoholic fermentation are oxidation–reduction reactions. Identify the ultimate electron donor and electron acceptor.

Answer 12

In both cases, the electron donor is glyceraldehyde 3-phosphate. In lactic acid fermentation, the electron acceptor is pyruvate, converting it into lactate. In alcoholic fermentation, acetaldehyde is the electron acceptor, forming ethanol.