Essential Knowledge 2.A.2: Organisms capture and store free energy for use in biological processes

 How do organisms produce ATP in the absence oxygen? ◦ Fermentation (glycolysis + fermentation = anaerobic respiration)  What type of organisms use fermentation? ◦ Facultative Anaerobes- an organism that makes ATP by aerobic respiration when oxygen is available but switches to fermentation when oxygen is not available ◦ Obligate Anaerobes – carry out only fermentation (anaerobic respiration) and cannot survive in the presence of oxygen

Glucose Glycolysis Pyruvate CYTOSOL No O 2 present: Fermentation O 2 present: Aerobic cellular respiration MITOCHONDRION Acetyl CoA Ethanol or lactate Citric acid cycle

 What are the two types of fermentation? ◦ Alcoholic Fermentation ◦ Lactic Acid Fermentation  Is ATP produced during fermentation? ◦ NO – but fermentation allows glycolysis to continue to make a net gain of 2 ATP per glucose by oxidizing NADH to NAD+. ◦ In fermentation as NADH is oxidized a carbon compound is reduced.

Alcoholic FermentationLactic Acid Fermentation  Pyruvate is converted to ehtanol in two steps ◦ Step 1 releases CO2 from pyruvate leaving acetaldehyde ◦ Step 2 oxidized NADH to NAD + and reduced acetaldehyde to ethanol  Occurs in bacteria, yeast, and some plants  Pyruvate is converted to Lactacte in one step ◦ Pyrvuate is reduced to lactate as NADH is oxidized to NAD +  Occurs in bacteria, fungi, and human muscle cells

2 ADP + 2 PiPi 2 ATP Glucose Glycolysis 2 NAD + 2 NADH 2 Pyruvate + 2 H + 2 Acetaldehyde 2 Ethanol (a) Alcohol fermentation 2 ADP + 2 PiPi 2 ATP GlucoseGlycolysis 2 NAD + 2 NADH + 2 H + 2 Pyruvate 2 Lactate (b) Lactic acid fermentation 2 CO 2