FERMENTATION
anaerobic respiration
The process of
breaking down
“food”
molecules in
the absence of
oxygen
OBJECTIVES: SWBAT…
¡  compare & contrast cellular respiration &
fermentation
¡  identify types of fermentation
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Cellular Energy: Fermentation
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POSSIBLE PATHWAYS OF MAKING
ENERGY AFTER GLYCOLYSIS
Glycolysis
Fermentation
Respiration
anaerobic
aerobic
(WITHOUT oxygen)
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(WITH oxygen)
Cellular Energy: Fermentation
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FERMENTATION
¡  fermentation - enables cells to carry out
energy production in the absence of oxygen
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FERMENTATION
¡  occurs when O 2 is
not present
§  anaerobic – any
process that does
not require oxygen
¡  occurs in cytoplasm
¡  allows glycolysis to
continue, yielding 2
ATPs for every 1
glucose molecule
Cellular
Energy: Fermentation
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2 T YPES OF FERMENTATION:
LACTIC ACID & ALCOHOLIC
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Cellular Energy: Fermentation
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2 T YPES OF FERMENTATION:
LACTIC ACID & ALCOHOLIC
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Cellular Energy: Fermentation
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Cellular Energy: Fermentation
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FERMENTATION: LACTIC ACID
¡  produced in some bacteria, fungi, & muscle
tissue
¡  examples of lactic acid fermentation:
§  bacteria causing milk to sour
§  bacteria change cabbage to sauerkraut
§  bacteria changing dairy products to cheese &
yogurt
§  build up of lactic acid in muscles (because of lack
of oxygen) causing cramps & stiffness
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Cellular Energy: Fermentation
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FERMENTATION: LACTIC ACID
¡  lactic acid fermentation does not produce
chemical energy
¡  vital (in absence of O 2 ) in regeneration of NAD +
¡  continuous supply of NAD + is required to keep
glycolysis running
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Cellular Energy: Fermentation
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FERMENTATION: LACTIC ACID
pyruvic acid + NADH à lactic acid + NAD +
low energy
molecule
¡  lactic acid is produced
in muscles during rapid
exercise when body
cannot supply enough
oxygen to tissue to
produce all of ATP that
is required
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Cellular Energy: Fermentation
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ENERGY & EXERCISE REVIEW
¡  for a few seconds of intense activity, your body
uses small amounts of ATP stored from glycolysis
& cellular respiration
¡  after a few seconds, your body uses ATP from
lactic acid fermentation, but only lasts 90
seconds.
¡  for longer activities, your body uses ATP from
cellular respiration breaking down glycogen
(carbohydrate) stored in your muscles & tissues,
but only lasts 15-20 minutes
¡  for long activities, your body breaks down other
stored molecules, such as fats
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CELLULAR RESPIRATION:
LONG-TERM ENERGY
¡  cellular respiration is the only way to generate
a continuing supply of ATP
¡  cell respiration releases energy more slowly
than fermentation, but it is steady
¡  after 15-20 minutes of activity, body starts to
break down fats & other stored molecules for
energy – results in weight loss
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Cellular Energy: Fermentation
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LACTIC ACID FERMENTATION:
QUICK ENERGY
¡  cells contain small amounts of energy (ATP)
produced during cellular respiration
¡  after a few seconds, stored ATP runs out
¡  lactic fermentation makes about 90 seconds
worth of energy – but then you’ll owe a big
oxygen debt
¡  heavy breathing after exercise is necessary to
take in more oxygen
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SUSTAINED ENERGY VS. QUICK ENERGY:
ENERGY & EXCERCISE
Sustained Energy
Quick Energy
¡  intake & distribution ¡  intake & distribution of O 2
can not keep up with ETC
of O 2 is able to keep
demands
up with ETC
¡  Glycolysis à Lactic Acid
demands
Fermentation
¡  muscle burn = lactic acid
¡  Glycolysis à Krebs
build up
à ETC
§  can lead to muscle failure
§  take energy & time to break
down & dispose of lactic
acid
§  long recovery time
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FERMENTATION: ALCOHOL
C2H5OH
pyruvic acid + NADH à alcohol + CO 2 + NAD +
low energy
molecule
¡  occurs in yeast & a few other microorganisms
¡  used by bakers and brewers
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FERMENTATION
¡  bread, beer & wine – obtained by alcoholic fermentation by
yeasts
¡  yogurt, buttermilk, cheese, sauerkraut, olives & salami are
mostly obtained by lactic acid fermentation by lactobacillae
¡  sour bread & pumpernickel are obtained by mixed alcoholic &
lactic acid fermentations by yeast & lactobacillae
¡  soy bean sauce is obtained from a process in which fungi, yeasts
& lactobacilli play a role
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FERMENTATION
energy
C 6 H 12 O 6 + low O 2 à CO 2 + waste + energy
Requirements:
¡  C 6 H 1 2 O 6 – organic
sugar comes from
digested foods
eaten
¡  low O 2 – oxygen is
in low supply or
not there at all
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Products:
¡  C O 2 – c a r b o n d i o x i d e i s
released
¡  waste – alcohol, or lactic
acid in humans, is released
as a waste product
¡  e n e r g y – c h e m i c a l A T P
energy is released
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RESPIRATION Vs. FERMENTATION
Respiration (with oxygen)
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COMPARING
PHOTOSYNTHESIS
energy
6CO 2 + 6H 2 0 à C 6 H 12 O 6 + 6O 2
BREAK DOWN OF GLUCOSE
energy
C 6 H 12 O 6 + 6O 2 à 6CO 2 + 6H 2 O + energy
FERMENTATION
energy
small
amount of
C 6 H 12 O 6 + low O 2 à CO 2 + waste + energy
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REVIEW
1.  What is fermentation? What are two types of
fermentation?
2.  How are respiration and fermentation
similar? How are they different?
3.  When oxygen is present, yeast cells undergo
respiration. Explain why brewers must take
special care to prevent air from entering
fermentation tanks?
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REVIEW
1.  fermentation is an anaerobic process that enables cells to
carry out energy production in the absence of oxygen. Two
types are lactic acid and alcoholic fermentation.
2.  Both respiration and fermentation produce ATP,
but respiration is aerobic and produces more ATP
than fermentation, which is anaerobic.
3.  Brewers must prevent oxygen from entering
fermentation tanks because they want to produce
alcohol through fermentation & this process will
not occur in presence of oxygen.
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