pag anaerobic rsp in yeast with redox indicators

Question 1

what and how is the experiment measuring

Answer 1

• measures the rate of dehydrogenase
• dehydrogenase catalyses NADH formation in glycolysis
• DCPIP or methylene blue indicator take up H and get reduced instead of NAD
• faster rate of respiration = faster rate of hydrogen release = faster the dyes get reduced and change colour

Question 2

colour change

Answer 2

blue to colourless

Question 3

outline method for when independent variable is temperature

Answer 3

• add set volume of yeast suspension to test tubes containing a certain concentration of glucose
• put test tube in a temperature-controlled water bath and leave for 5 minutes
• add set volume of DCPIP to the test tube and start stopwatch immediately
• stop stopwatch when solution becomes colourless
• record time taken for a colour change once the dye is added
• repeat across a range of temperatures

Question 4

control variables

Answer 4

• volume of dye
• volume of yeast suspension
• type of substrate
• concentration of substrate
• temperature
• pH

Question 5

limitations

Answer 5

• not measuring rate of dehydrogenase directly, only predicting rate by measuring rate of electron transfer
• colour change subjective