Download Nucleic Acids

Fermentation
Chapter 9
What you need to know!
• The difference between fermentation and
cellular respiration.
Anaerobic Cellular Respiration
• Production of ATP in the absence of
oxygen
2 types of fermentation:
• Alcoholic fermentation
• Lactic acid fermentation
Organisms
• Facultative anaerobic organisms
– Can do aerobic or anaerobic cellular respiration
(CR) depending on the situation
– Ex: yeast
• Obligate Anaerobic Organisms
– Require oxygen free environment (die in the
presence of O2)
– Ex: certain soil and lake bacteria
• Obligate aerobic organisms
– Require O2
– Ex: All vertebrates
Fermentation: 2 step process
1. Glycolysis
•
•
ATP generation
(NAD+) + (H+) + e-  NADH
2. Fermentation (regeneration)
•
•
NAD+ regeneration
NADH  (NAD+) + byproducts (specific to
fermentation type)
Alcoholic Fermentation
• Location: cytoplasm of yeast and other bacteria
• Reason: NADH must be recycled back into NAD+
so glycolysis can continue
Rx: Pyruvic acid + NADH + H+  Ethanol + CO2 + NAD+
• CO2 creates carbonation in bear, fizz in
champagne, and leavens dough
• Small quantities of alcohol are made whenever you
eat by anaerobic organisms that live in your
intestines
• The liver degrades alcohol using alcohol
dehydrogenase
Lactic Acid Fermentation
• Location: cytoplasm of muscle cells
• Reason: O2 deficiency
Rx: Pyruvic acid + NADH + H+  Lactic Acid + NAD+
• Lactic acid causes muscle soreness
(burning)
• It takes days to break down lactic acid
Muscle Categories
• Fast Twitch
• Strength, large diameter, white color,
produce lots of lactic acid
• Ex: biceps, chest muscles
• Slow Twitch
• Endurance, slim diameter, red color, have
lots of mitochondria, intense vascularization
• Ex: posture muscles
ATP Yield
• Anaerobic yields 4 ATP during glycolysis
– 2 ATP activation cost
• Net Gain 2 ATP
• Aerobic yields 38 ATP during all 3 steps
– 2 ATP activation cost
• Net Gain 36 ATP
• Aerobic CR is 18 X’s more efficient per
glucose molecule