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– 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

FermentationFermentation

1) Alcoholic Fermentation:

● occurs in yeast cells & some other microorganisms

● pyruvic acid is broken down

2 Fermentation Pathways:

● pyruvic acid is broken down into a 2-Carbon alcoholplus 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 breadgas—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 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– Your body stores energy in muscle cells and liverin 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!