Cellular Respiration
and Fermentation
Plant Biology 1
Respiration and
Fermentation
 Process of converting glucose to a
useable form of energy
 Respiration uses Oxygen and is very
efficient
 Fermentation does not need Oxygen but
is very inefficient
ATP




Adenosine Tri-phosphate
A compound that “powers” the cell
All cell parts need ATP to work properly
Without ATP, the cell dies.
ATP
So where can we get ATP?
Glycolysis, Cell respiration or fermentation
Glycolysis
 Cells cannot break down large compounds
 Glucose must be changed so the cell can use
it.
 Through a series of chemical reactions,
glucose is changed to pyruvic acid
 During this process, 6 molecules of ATP are
produced (8 are produced, but 2 are used up)
Pyruvic acid
 Energy compound produced at the end of
glycolysis
Glucose
2 ATP’s used
8 ATP’s
produced
Glycolysis
Pyruvic Acid
Respiration (an aerobic
process)
 Process of converting pyruvic acid to ATP
in the presence of oxygen
 One pyruvic acid molecule can produce
30 molecules of ATP
 By-product of respiration is CO2 + H20
 Takes places inside each cell, in the
mitochondria (organelle)
Respiration
C6H12O6 + 6O2= 6CO2 +6 H2O
This reaction produces
30 ATPs!
Glucose
2 ATP’s used
8 ATP’s
produced
Glycolysis
Pyruvic Acid
Respiration
30 ATP’s
produced
CO2 and H2O
What if there is no, or not
enough oxygen?
Fermentation
Fermentation (an
anaerobic process)
 Process of producing some ATP without
oxygen present
 Much less efficient
 Only 2 ATP’s are produced from each glucose
molecule
 All cells are capable of fermentation
 Two types
 Lactic Acid fermentation
 Alcoholic fermentation
Lactic Acid Fermentation
 “Feeling the burn!”
 When a cell runs out of oxygen, it makes
ATP by repeating the glycolysis process.
 Fermentation replaces a special
compound lost during glycolysis
 Fermentation does not produce ATP, but
merely allows the cell to go through the
glycolysis process repeatedly.
Lactic Acid fermentation
 Fermentation uses sugar much faster
than respiration
 This is why exercise is better if your cells
are functioning in this mode (anaerobic).
 Lactic acid and carbon dioxide are the by
products of fermentation. If you produce
them, your body must get rid of them
quickly, or they can cause damage to
your cells.
Alcoholic Fermentation
 Similar to lactic acid fermentation, but the
by-product is ethyl alcohol, instead of
lactic acid, and carbon dioxide
 The carbon dioxide produces the air
spaces in bread, and the ethyl is the toxin
that impairs brain function when
consumed.
2 ATP’s used
Glucose
8 ATP’s
produced
Glycolysis
2 ATP’s
produced
No
Pyruvic Acid
Is oxygen
present?
Fermentation
Yes
Respiration
30 ATP’s
produced
Ethyl alcohol
or lactic acid
and CO2
CO2 and H2O
Something to think about
 What is the advantage of aerobic
respiration vs anaerobic?
 Why wouldn’t all cells just do aerobic?
 In what situations would anaerobic be
better?