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
animals)
+ ENERGY (anaerobic resp. in
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.