Download Enduring Understanding: Growth, reproduction and maintenance of

Essential Knowledge 2.A.2: Organisms capture
and store free energy for use in biological
processes

How do organisms produce ATP in the
absence oxygen?
◦ Fermentation (glycolysis + fermentation =
anaerobic respiration)

What type of organisms use fermentation?
◦ Facultative Anaerobes- an organism that makes
ATP by aerobic respiration when oxygen is available
but switches to fermentation when oxygen is not
available
◦ Obligate Anaerobes – carry out only fermentation
(anaerobic respiration) and cannot survive in the
presence of oxygen
Glucose
Glycolysis
CYTOSOL
Pyruvate
No O2 present:
Fermentation
O2 present:
Aerobic cellular
respiration
MITOCHONDRION
Ethanol
or
lactate
Acetyl CoA
Citric
acid
cycle

What are the two types of fermentation?
◦ Alcoholic Fermentation
◦ Lactic Acid Fermentation

Is ATP produced during fermentation?
◦ NO – but fermentation allows glycolysis to continue
to make a net gain of 2 ATP per glucose by
oxidizing NADH to NAD+.
◦ In fermentation as NADH is oxidized a carbon
compound is reduced.

Pyruvate is converted
to ehtanol in two steps
◦ Step 1 releases CO2 from
pyruvate leaving
acetaldehyde
◦ Step 2 oxidized NADH to
NAD+ and reduced
acetaldehyde to ethanol

Occurs in bacteria,
yeast, and some plants
Alcoholic Fermentation

Pyruvate is converted
to Lactacte in one step
◦ Pyrvuate is reduced to
lactate as NADH is
oxidized to NAD+

Occurs in bacteria,
fungi, and human
muscle cells
Lactic Acid Fermentation
2 ADP + Pi
2
Glucose
2 ATP
Glycolysis
2 Pyruvate
2
NAD+
2
+ NADH
2
H+
2 CO2
2 Acetaldehyde
2 Ethanol
(a) Alcohol
fermentation
2 ADP + Pi
2
Glucose
Glycolysis
2
NAD+
2 Lactate
(b) Lactic acid
fermentation
2 ATP
2
+ NADH
2
H+
2 Pyruvate