Download NOTES: 9.3 FERMENTATION

NOTES: 9.3
FERMENTATION
Vocabulary:
-Fermentation
-Aerobic
-Anaerobic
-Glycolysis
-Lactic Acid Fermentation
-Alcoholic Fermentation
What happens if your cells aren’t
getting enough oxygen?
● Krebs Cycle & E.T.C. CANNOT proceed without
oxygen
● Instead, FERMENTATION occurs
– Pyruvic Acid builds up in animal muscle cells
& is converted to LACTIC ACID… feel the
burn!
– In other organisms, the pyruvic acid builds up,
ferments, and becomes alcohol
● Fermentation: the release of energy from
food molecules in the absence of oxygen
(anaerobic)
● Enables cells to carry out energy production
in the absence of oxygen
● result of glycolysis + fermentation yields 2
ATP molecules per 1 molecule of glucose
(not nearly as much energy!!!!)
2 Fermentation Pathways:
1) Alcoholic
Fermentation
2) Lactic Acid
Fermentation
2 Fermentation Pathways:
1) Alcoholic Fermentation:
● occurs in yeast cells & some
other microorganisms
● pyruvic acid is broken down
into a 2-Carbon alcohol
plus carbon dioxide
Alcoholic Fermentation:
● Important to brewers & bakers!
– When yeast in dough runs out of oxygen it
ferments, giving off bubbles of carbon dioxide
gas—which forms air space in bread
– Alcohol produced in the dough evaporates
when bread is baked
*(when the level of alcohol reaches 12%,
yeast cells die)
2) Lactic Acid Fermentation:
● pyruvic acid from
glycolysis is converted to
lactic acid
● lactic acid is produced in
muscles during rapid
exercise (body can't
supply enough O2 to the
tissues)
● the build-up of lactic acid
causes a burning, painful
sensation in your
muscles
Energy & Exercise: Quick Energy
● Muscle cells only contain enough ATP for a
few seconds of energy, or a “burst” energy
– e.g. – an emergency, starting gun of race
● When this is gone, cells resort to lactic acid
fermentation which can provide enough ATP
for about 90 seconds
Energy & Exercise: Long Term
Energy
● If a race or energy need is longer, your body
must go through cellular respiration to
get enough ATP to continue
– Even well-conditioned athletes have to pace
themselves
– Your body stores energy in muscle cells and liver
in the form of GLYCOGEN
– these stores are enough to last for 15-20
minutes of activity when broken down through
cellular respiration
– After this, your body begins to break down other
molecules, including fats, for energy
– This is why aerobic exercise is beneficial for
weight control!!
Long Term Energy:
● some animals rely on stored fat for energy to
get them through long periods without food
● EXAMPLE: a bear going into hibernation!