Glycolysis and Fermentation Chapter 5 Continued

Before we start, what is cellular respiration? The process in which organisms take molecules broken down from food and release the chemical energy stored in the chemical bonds of those molecules. It’s important to remember that food is not the direct source of energy. The energy that is released from chemical bonds during cellular respiration is stored in molecules of ATP.

Glycolysis Glycolysis is an anaerobic step in the cellular respiration pathway therefore it doesn’t require oxygen. Glycolysis takes place in the cytoplasm of the cell and is a series of reaction using enzymes.

Glycolysis Glyco = glucose Lyse = break down One molecule of glucose (C6H12O6) is broken in half This produces 2 molecules of pyruvic acid (a 3-carbon compound)

Glycolysis Glycolysis is a chemical reaction that releases energy from glucose. This anaerobic pathway provides all the energy needs of many one celled and some multicellular organisms.

Glucose to ATP Glycolysis also occurs very rapidly. It can produce thousands of ATP molecules in a few milliseconds. The initial energy COST of this chemical reaction is 2 ATP molecules. 4 molecules of ATP are produced. Net gain of 2 ATP!!!

Glycolysis Glycolysis is inefficient! Between 2% and 4% efficiency compared to cellular respiration that has an efficiency of 35% to 40%

To the electron transport chain Glycolysis Glucose 2 Pyruvic acid To the electron transport chain

Fermentation Fermentation is also anaerobic. Fermentation happens after glycolysis IF the cell does NOT have Oxygen. Fermentation releases energy from food molecules in the absence of oxygen.

Fermentation There are 2 main types of fermentation: Alcoholic Fermentation Lactic Acid Fermentation Occur in the cytoplasm

Alcoholic Fermentation Pyruvic acid + 2NADH  alcohol + CO2 + 2NAD+ Examples: wine and bread (the alcohol evaporates when baked)

Lactic Acid Fermentation Pyruvic acid + 2NADH  lactic acid + CO2 + 2NAD+ Examples: milk, yogurt, & muscles

Exercise Without oxygen, the body is not able to produce enough ATP. When you perform ANAEROBIC exercise, you are depriving your muscles of oxygen. Your muscles go through LACTIC ACID FERMENTATION! The lactic acid is what makes you sore!!!

Structure & Function: Glycolysis & Fermentation Glucose Glycolysis Pyruvate If O2 Present Lactic Acid Fermentation Alcoholic Fermentation Lactic Acid Ethanol

If the cell has oxygen… Aerobic—process that occurs in the presence of oxygen Pyruvic Acid goes to the mitochondria; fermentation does NOT occur Kreb’s Cycle Electron Transport Chain To be continued… after the break!