Required practical 9 Flashcards
What does the dehydrogenase enzyme do in yeast?
Dehydrogenase enzyme occurs naturally in yeast and catalyses reactions involved in removing H from coenzymes and carbon compounds. It is involved in all stages of aerobic respiration when NADH is made but also oxidative phosphorylation where NADH is reduced back into NAD.
What is a redox indicator and name an example?
TTC is a redox indicator that turns colourless when oxidised but red when reduced. It can pick up hydrogen removed by dehydrogenase during respiration.
Why leave the 2 test tubes carrying yeast/glucose solution and TTC for 5 minutes in a water bath before the experiment?
To allow them to equilibrate to the temperature of the water bath so the experiment is reliable.
Why periodically stir the solution?
To prevent yeast from settling at the bottom.
Which statistical test will you use to compare these variables?
Spearman’s rank.
What are the limitations to this practice?
- Endpoint is subjective (ideally use a colorimeter for quantitive data).
- Difficulties in seeing the colour change in the water bath
At which stages of respiration will dehydrogenase be removing hydrogen?
The oxidation of NADH in oxidative phosphorylation and anaerobic respiration. Also when NADH is made by oxidation of a carbon compound during all stages of respiration.
