Unit 4.3: Glycolysis and Fermentation

Question 1

What is glycolysis? What does it produce?

Answer 1

Partial oxidation, or ‘splitting’ of sugar. Produces two 3-carbon molecules of pyruvate (from 6-carbon glucose), and a net total of two ATP and two NADH electron carrier.

Question 2

First phase of glycolysis

Answer 2

Preparatory phase: Prepares the glucose for splitting by adding two phosphate groups (consumes 2 ATP).

Question 3

Second phase of glycolysis

Answer 3

Cleavage phase: 6-carbon glucose molecule is split into two 3-carbon molecules.

Question 4

Third phase of glycolysis

Answer 4

Payoff phase: 4 ATP and 2 NADH electron carrier are produced. 2 pyruvate molecules are produced.

Question 5

What is fermentation?

Answer 5

The process of metabolizing pyruvate molecules after glycolysis in the absence of oxygen.

Question 6

What is needed for glycolysis to continue? How is this done with or without oxygen?

Answer 6

NADH must be oxidized to NAD+.
Oxygen: NAD+ is regenerated when NADH donates its electrons to the electron transport chain.
No oxygen: NADH is oxidized to NAD+ when pyruvate is made.

Question 7

Lactic acid fermentation

Answer 7

One of the pathways of fermentation. Occurs in animals/bacteria. Electrons from NADH are transferred to pyruvate which produces lactic acid and NAD+.

Question 8

Ethanol fermentation

Answer 8

One of the pathways for fermentation. Occurs in plants and fungi. Pyruvate releases CO2 to form acetaldehyde. Electrons from NADH are transferred to acetaldehyde to produce ethanol and NAD+.