Cellular Respiration
and Combustion
Mrs. Dignan’s Science Class
The 1st Law of thermodynamics
Write down the 1st Law
of Thermodynamics
from memory
 Matter and energy
cannot be created or
destroyed.
 They can change
forms, though.
4 important chemical reactions
1.
2.
3.
4.
Photosynthesis
Combustion
Cellular Respiration
Fermentation
1. Photosynthesis
CO2 + H2O + sunlight → C6H12O6 + O2
 Balance the equation now.
 Photosynthesis is performed by autotrophs

 Autotroph=
bacteria.
plants, algae, and photosynthetic
1. Photosynthesis
Carbohydrates
are the product
 Oxygen is the
by-product

2. Combustion
Combustion is the process of burning
carbon-and-hydrogen-containing
compounds (hydrocarbons)in the presence
of oxygen
 Hydrocarbon + O2 → CO2 + H2O + Energy
 Fuel + Heat + Oxygen
Combustion!

2. Combustion
Balance the equation for the combustion
of propane gas (C3H8)
 C3H8 + O2 → CO2 + H2O + Energy
 Name 4 things that humans use
combustion reactions for.

3. Aerobic Cellular Respiration

Cellular respiration is the process of
getting energy from the sugars in food in
the presence of oxygen.
C6H12O6 + O2 → CO2 + H2O + 36ATP
 Balance the equation now.

3. Aerobic Cellular Respiration




Cellular respiration happens
in the cells of an organisms
Cellular respiration
(breathing) is why most
organisms need oxygen
(including us)
This is why we need to eat
food (and mainly
carbohydrates).
Cellular respiration occurs in
the mitochondria of the cell.

For this reason, the
mitochondria are known as
the “powerhouses” of the
cell.
ADP
Adenosine
Triphosphate
 ATP is created
by adding a
phosphate
group to ADP.
This requires
energy.

ATP
ATP

ATP is “used
up” for
energy by
the cell and
converted
back into
ADP
(Adenosine
Diphosphate)
ADP
ATP or ADP?
ATP or ADP?
ATP or ADP?
ATP or ADP?

Create your own analogy!
4. Fermentation
Fermentation is the process of converting
sugars into ATP WITHOUT oxygen.
 Fermentation is also called anaerobic
cellular respiration
 C6H12O6 → CO2 + C2H6O + 2ATP
 Balance the equation now.

4. Fermentation
Fermentation is often
performed by yeast and
bacteria.
 Yeast produce CO2 gas as
they ferment, making
bread rise.
 Yeast also make beer
alcoholic (ethanol) and
foamy (CO2).

Fermentation
Some fermenting
bacteria produce Lactic
Acid instead of alcohol.
 Lactic acid makes
fermented foods taste
sour or tangy.
 Lactic Acid Fermentation
is used to produce “sour”
products like yogurt,
sour cream, kimchi,
pickles, sourkraut, etc.

4. Fermentation
Anaerobic cellular respiration also
occurs in our muscles during
VIGOROUS exercise.
 If your body is working so hard
that your lungs can’t keep up
(you can’t get enough Oxygen to
your muscles), your muscle cells
have to do anaerobic cellular
respiration
Aerobic

Anaerobic