1. Release of energy from glucose.
Combustion or Cell Respiration?
Figure 1 Robin Müller [CC-BY-SA-3.0 ( via Wikimedia Commons

2. Glucose molecules All sugar molecules contain a lot of energy.
Combustion of Sugar Demo
Description: A sugar cube will not burn unless it is first rubbed with ash.
Concept: Ashes catalyze the burning of sugar. A catalyst speeds up a reaction.
Materials:
Sugar cubes
Bunsen burner or propane torch
tongs
ashes (from burned plant material)
Safety: Be careful not to burn yourself.
Procedure: With tongs, hold a sugar cube in a flame (it will melt but will not burn).
Rub a sugar cube with ash. Hold this cube in a flame (it will burn).
Clean-up: If the sugar melts and makes a mess, clean it up. Leave the room clean for the next lecturer.
All sugar molecules contain a lot of energy.
This energy is released rapidly in combustion,
the temperature can reaches 300°C .
This energy release is too rapid for living cells .

3. Combustion & Respiration
The equation for combustion is the same as respiration.
Word Equation:
Glucose + Oxygen  Carbon Dioxide + Water.
Symbol Equation:
C6H12O O2  6CO H2O +

4. What is the difference? Respiration breaks down glucose in cells
to release its energy to form ATP.
ATP is an energy carrying molecule made from ADP
Energy from the breakdown of glucose is used to form ATP

5. Respiration temperatures are lower
Respiration is a ‘controlled release of energy’
It breaks down glucose in small steps. Focus on the carbon atoms …as molecules get smaller they release energy.
Glucose  Pyruvate  Acetyl  Carbon Dioxide
6C 3C 2C 1C

6. A fuller picture of Respiration

7. Cell Respiration in Words

8. Cell Respiration in Sentences
Cell respiration is the controlled release of energy from organic compounds in cells to form ATP.
In cell respiration, glucose in the cytoplasm is broken down into pyruvate, by glycolysis with a small yield of ATP.

9. In Aerobic Respiration
In the presence of oxygen
Pyruvate is broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP.

10. In Anaerobic Respiration
In the absence of oxygen
Pyruvate can be converted into lactate, (in humans) or into ethanol and carbon dioxide, (in yeast) in the cytoplasm with no further yield of ATP.