1. Yeast, resazurin, and respiration
cheap/quick/versatile/easy practical activities and investigations which produce quantitative results

2. National 5 Unit 1 Cell Biology 8. Respiration
‘Use immobilised yeast and hydrogen carbonate indicator, resazurin or gas sensors and data loggers to investigate rate of respiration’
Higher Biology/Higher Human Biology
Unit 2 Metabolism and Survival/Unit 1 Human Cells
2. Cell Respiration/7. Cellular Respiration
(c) Metabolic pathways of cellular respiration
‘Experiments with yeast dehydrogenase, eg using resazurin’
(e) Substrates for respiration
‘Investigation of different sugars as respiratory substrates in yeast’

3. Advanced Higher Biology Project
Optimising conditions for the growth of yeast:
beer/wine/whisky/flavourings/crisps
Using yeast to produce ß-glucan

4. How can we quantify yeast growth?

5. Base practical Time (minutes) A B (no glucose control)
C (boiled yeast control) 3 6 9 12 15 18 21 24 27 30

6. Results

7. Immobilising yeast

8. Immobilised yeast
Yeast suspension is too turbid to take measurements in a colorimeter
Instead of adding yeast suspension to each tube you can add immobilised yeast beads
Beads can be used immediately or stored in distilled water until required

9. At 590nm you will be measuring the disappearance of the blue colour of the resazurin dye
Blank the colorimeter with the appropriate carbohydrate solution
Take colorimetric readings every 3 minutes remembering to pour the solution back into the correct tube after each measurement

10. Investigations into respiration rate in yeast
Type of yeast used (fresh, dried, frozen)
Concentration of the yeast suspension
Temperature
Respiratory substrate (sucrose / starch / maltose / fructose)
Concentration of the substrate
Compare respiration rates in immobilised and non-immobilised yeast

11. Investigations GROUP A
Investigating yeast concentration using colour chart
GROUP B
Investigating temperature using colour chart
GROUP C
Investigating yeast concentration using immobilised yeast and colorimeter
GROUP D
Investigating temperature using immobilised yeast and colorimeter

12. Advanced Higher Biology Project
Optimising conditions for the growth of yeast:
beer/wine/whisky/flavourings/crisps
Using yeast to produce ß-glucan