Respirometer & Anaerobic Respiration

RESPIROMETER Used to investigate the rate of oxygen uptake during respiration Involves an experimental tube (where respiring organism is found) and a

control tube both linked by a manometer (measures pressure of a gas). Tubes are sealed from the atmosphere In the experimental tube the organism to be investigated is placed on a

platform that prevents contact with soda lime/potassium hydroxide below and a tube that leads directly out of the tube into the manometer.

In the control tube (A) glass beads would replace the organism (to verify the value of O2 used by the organism)

RESPIROMETER Soda lime/ Potassium hydroxide removes CO2 to allow

the measurement only of O2 used up by the organism.

Temperature on the rate of respiration is also investigated by placing the apparatus in a water bath at various temperatures

ALCOHOLIC FERMENTATION (YEAST) A form of anaerobic respiration. Pyruvate is converted to ethanal and CO2

Ethanal is further reduced to ethanol and the NADH produced in glycolysis is oxidised back to NAD+ to go another round in glycolysis.

This replenishes the NAD+ stores (which is limited) allowing glycolysis to continue and the net production of 2 ATP

ALCOHOLIC FERMENTATION (YEAST) C6H12O6 2C2H5OH + 2CO2 + ENERGY (anaerobic

resp. in yeast and some bacteria)

GLUCOSE 2ETHANOL + 2CO2 + ENERGY

This concept is used commercially and industrially in the manufacture of alcoholic beverages.

ALCOHOLIC FERMENTATION (YEAST)

COMMERCIAL USES OF YEAST Manufacture of alcoholic beverages. eg beer, whisky,

sake (Japanese). Used in the food industry for the baking of bread,

cakes and other pastries. Used in the manufacture of diary products eg.cheese,

butter and yogurts.

BEER & BREAD

LACTATE FERMENTATION (ANIMALS) A form of anaerobic respiration Pyruvate in animals is converted to lactate by lactate

dehydrogenase and NADH produced by glycolysis is oxidised back to NAD so that it can go another round in glycolysis.

C6H12O6 2C3H6O3 + ENERGY (anaerobic resp. in animals)

GLUCOSE 2LACTATE + ENERGY This ensures the net production of 2 ATP.

LACTATE FERMENTATION (ANIMALS)

OXYGEN DEBT oxygen debt in mammals- lactate fermentation supplies that

extra ATP which gives the individual “a push” in times of low oxygen during vigorous exercise

build up of harmful lactic acid (lactate) which changes the pH of the blood, can lead to the denaturing of enzymes, muscle cramps especially in the lower abdomen, thighs, carves and arms.

OXYGEN DEBT when exercise is stopped and the individual goes from

breathing to panting, the supply of O2 is increased to the tissues

This causes the reconversion of lactate to pyruvate (by stimulating Lactate Dehydrogenase LDH, the same enzyme that converted pyruvate to lactate in the first place)

aerobic respiring status is restored as pyruvate is needed for this to occur.