Fermentation

Stages & Locations of AEROBIC Respiration:

  • Mitochondrial Matrix

  • Link, Krebs, OxPhos

Stages & Locations of ANAEROBIC Respiration:

  • Glycolysis

  • cytoplasm

  • if there’s no O2 present after Glycolysis, the Pyruvate will stay in the cytoplasm and enter Fermentation

    • either Alcohol Fermentation or Lactic Acid Fermentation

Glycolysis Review:

  • Glucose is converted into 2 Pyruvate molecules

  • 2 ATP (net) produced

  • 2 NADH produced

  • glucose, ADP, NAD+ must be present for glycolysis to continue

During AEROBIC Respiration:

  • NADH will become NAD+ when NADH drops off electrons at the ETC

  • ATP will become ADP when ATP is continuously being used for various cellular functions

  • if there’s no O2 present, NADH CANNOT drop off their electrons w/the ETC

Goal of Fermentation: it regenerates NAD+ to allow glycolysis to continue under anaerobic conditions

  • occurs in the cytoplasm

  • all cells can do fermentation

Two Types of Fermentation: Alcohol fermentation & Lactic Acid fermentation

Why is it important for glycolysis to continue under anaerobic conditions?

  • Glycolysis is how ATP is created in anaerobic conditions —> w/o it, there’d be no way to make ATP

  • net 2 ATP

Alcohol Fermentation:

State which process occurs first:

  • 1st, Glycolysis: Glucose —> 2 Pyruvate + 2 ATP + 2 NADH

  • Then: 2 Pyruvate + 2 NADH —> 2 Ethanol + 2 CO2 + 2 NAD+

Overall Inputs & Outputs:

Glucose —> 2 Ethanol + 2CO2 + 2 ATP

  • Yeast: an organism that uses alcohol fermentation

  • Industry Uses: baking bread & alcoholic beverages

Lactic Acid Fermentation:

State which process occurs first:

  • 1st, Glycolysis: Glucose —> 2 Pyruvate + 2 ATP + 2 NADH

  • Then: 2 Pyruvate + 2 NADH —> 2 Lactate + 2 NAD+

Overall Inputs & Outputs:

Glucose —> 2 Lactate + 2 ATP

  • humans, animals, and some bacteria use Lactic Acid Fermentation

  • Industry Uses: yogurt, cheese, pickles, kimchi

Lactic Acid Fermentation in Humans:

  • Not a good long-term solution for humans, because we have large ATP requirements & only 2 ATP (net), are produced in Lactic Acid Fermentation

  • however, it is effective for generating ATP for short, intense exercises (EX: sprinting)

Pros & Cons of Anaerobic Respiration:

  • Pros: produces ATP in the absence of O2 —> faster & doesn’t require special structures (ETC/ATP Synthase)

  • Cons: much fewer ATP than aerobic (2 vs. 36-38)

Pros & Cons of Aerobic Respiration:

  • Pros: much more ATP is produced

  • Cons: requires O2, requires special structures (ETC, ATP Synthase), slower

  • Pyruvate is like a “fork in the road” of cellular respiration —> can go to fermentation OR Acetyl CoA & Krebs Cycle