Lab 4 - Fermentation

Question 1

Define fermentation and an equation to describe it

Answer 1

Chemical process by which MCOs such as bacteria fungi and yeasts break down sugars into water, alcohol and CO2

glucose -> ethanol + carbon dioxide

Question 2

Why is methylene blue used in this experiment?

Answer 2

Able to enter all yeast cells dead/alive and oxidised to colourless compound in live cells

Question 3

Compare the energy produced from fermentation vs aerobic and anaerobic respiration

Answer 3

Fermentation = 2 ATP from substrate level phosphorylation
Anaerobic respiration = 2 ATP from oxidative phosphorylation with exogenous electron acceptors
Aerobic respiration = 38 ATP from oxidative phosphorylation with endogenous electron acceptors

Question 4

Briefly describe the method used in this experiment

Answer 4

1. Inoculate apple juice in Durham tube with loopful of yeast culture
2. Incubate for 1 week at room temperature

Question 5

What were the expected results of this experiment?

Answer 5

1. Gas production in the Durham tube
2. Strong alcohol odour
3. Wet mount with approx. 10% dead cells coloured blue from methylene blue dye