Cellular Respiration
•Respiration is the transfer of stored energy in food molecules to a more usable
form.
•Respiration involves the exchange of gases between the organism and the
environment.
•Cellular respiration involves a series of enzyme-controlled reactions in which
energy in food is broken down into energy that the organism can use (ATP).
•This energy is the energy used by the body to carry out the life functions.
ATP = Adenosine Triphosphate = 3 Phosphates
When ATP is broken down, energy is released, and
a phosphate is lost, and ADP is formed.
ADP = Adenosine Diphosphate = 2 Phosphates
Water + ATP
ADP + P + Energy
This is called Hydrolysis.
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Dehydration Synthesis is the reverse of hydrolysis.
Dehydrate means to remove water.
ADP + P + Energy
Water + ATP
There are two types of respiration: Anaerobic and Aerobic
Anaerobic respiration is when the organism does not
use oxygen.
Aerobic respiration is when the organism uses free
oxygen to carry out respiration.
The majority of organisms carry out aerobic
respiration.
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Anaerobic Respiration
•Also called Fermentation or Glycolysis
•Some cells lack the enzymes necessary for anaerobic respiration, while
others revert to anaerobic respiration when oxygen is lacking.
•The enzymes needed for anaerobic respiration are found in the
cytoplasm.
•Glucose is broken down in a series of enzyme controlled reactions into
either lactic acid or alcohol and carbon dioxide.
•Lactic acid is produced in animals and causes muscle fatigue.
•Lactic acid is also produced by some bacteria and is important in
making cheeses, buttermilk, and yogurt.
•Alcohol and CO2 are produced by yeast and bacteria and are important
in brewing and baking.
Anaerobic Respiration produces 2 ATP Only
Glucose
Glucose
(enzymes)
(enzymes)
2 Lactic Acids + 2 ATP
OR
2 Alcohol + 2 CO2 + 2 ATP
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Aerobic Respiration
•Oxygen is used during aerobic respiration.
•Aerobic respiration takes place in the mitochondria.
•During this process, and due to the presence of oxygen, the chemical
energy of glucose is released gradually in a series of enzyme-controlled
reactions (Krebs Cycle).
•Aerobic Respiration is more efficient because more ATP energy is
created at the end.
•If oxygen is present after anaerobic respiration, then aerobic
respiration can occur.
•Pyruvic Acid is the intermediate substance produced in both alcohol
and lactic acid fermentation, before aerobic respiration take place.
6 H2O + 6 CO2 + 36 ATP
C6H12O6 + 6 02
Water + Carbon Dioxide + Energy
Glucose + Oxygen
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Comparing Photosynthesis to Cellular Respiration
Photosynthesis
Cellular Respiration
In Chloroplasts
In Mitochondria
CO2 + H2O = C6H12O6 +
O2
O2 + C6H12O6 = CO2 + H2O
They are basically the opposite. Photosynthesis produces sugar
and oxygen needed for life functions. Cellular Respiration uses
oxygen and sugar to produce Carbon Dioxide and Water. Only
plants use Photosynthesis.
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