4.6 Fermentation
KEY CONCEPT
Fermentation allows the production of a small
amount of ATP without oxygen.
4.6 Fermentation
Objectives
• Describe the process of fermentation.
• Summarize the importance of fermentation.
4.6 Fermentation
Vocabulary
• Fermentation
– Anaerobic process by which ATP is produced by
glycolysis.
• Lactic Acid
– Product of fermentation in many types of cells,
including human muscle cells.
4.6 Fermentation
Fermentation allows glycolysis to continue.
• Fermentation allows glycolysis to continue making ATP
when oxygen is unavailable.
• Fermentation is an anaerobic process.
– occurs when oxygen is not available for cellular
respiration
– does not produce ATP
4.6 Fermentation
• Fermentation allows glycolysis to continue making ATP
when oxygen is unavailable.
• NAD+ is recycled to glycolysis
• Lactic acid fermentation occurs in muscle cells.
– glycolysis splits glucose into two pyruvate molecules
– pyruvate and NADH enter fermentation
– energy from NADH converts pyruvate into lactic acid
– NADH is changed back into NAD+
4.6 Fermentation
Fermentation and its products are important in several
ways.
• Alcoholic fermentation is similar to lactic acid
fermentation.
– glycolysis splits glucose and the products enter
fermentation
– energy from NADH is used to split pyruvate into an
alcohol and carbon dioxide
– NADH is changed back into NAD+
– NAD+ is recycled to glycolysis
4.6 Fermentation
• Fermentation is used in food production.
– yogurt
– cheese
– bread
4.6 Fermentation
Question/Answer
• How do long-distance runners, such as marathoners,
provide the energy their bodies need for a race?
– By carb-loading, eating carbohydrate-rich foods.
• What has happened to a runner who “hits the wall”?
– The carbohydrates are depleted. The body now burns
more fat, which requires more oxygen, energy, and
time to burn.
- “Hitting the wall” means a runner is making ATP through
glycolysis and fermentation.
• Which process must happen first, fermentation or
glycolysis? Explain.
– Glycolysis must occur first because fermentation
require pyruvate and NADH.
4.6 Fermentation
Question/Answer
• How are alcoholic fermentation and lactic acid
fermentation similar?
– They both begin with glycolysis of glucose and
produce ATP and NAD+
• How are the different?
– Lactic acid fermentation produces lactic acid; alcoholic
fermentation produces alcohol and carbon dioxide.
• Explain the importance of alcoholic fermentation in the
production of bread’s light, fluffy texture.
– Carbon dioxide produced from alcoholic fermentation
creates gas pockets in the bread, which cause the
bread to rise.