Cellular Respiration
Introduction
The reactions within cells which result in the synthesis of ATP using energy
stored in glucose are referred to as cellular respiration. Aerobic respiration
requires oxygen as the final electron acceptor. Fermentation does not require
oxygen.
The equation for aerobic respiration is below.
C6H12O6 + 6O2 -> 6CO2 + 6 H2O + 36 or 38 ATP
In aerobic respiration (equation above) glucose is completely broken down to
CO2 + H2O but during fermentation, it is only partially broken down. Much of
the energy originally available in glucose remains in the products produced.
Plant and fungal cells produce alcohol as a result of fermentation and animal
cells produce lactic acid. The equation for alcohol fermentation is below.
C6H12O6 -> 2CO2 + 2C2H5OH + 2 ATP
Notice from the above equations that aerobic respiration produces much more
ATP per glucose molecule than fermentation.
Fermentation
We will investigate fermentation by measuring the amount of carbon dioxide
produced by yeast. The rate of cellular respiration is proportional to the
amount of CO2 produced (see the equation for fermentation above).
In this experiment, we will measure the rate of cellular respiration using either
distilled water or one of four different food sources. Create a hypothesis
regarding the rate of cellular respiration for each of the different food sources
listed in the step below.