9-1 Making ATP Without Oxygen

Chemical Energy and Food calorie: the amount of energy needed to raise the temperature of 1 gram of water 1ºC energy from food (glucose) is released by cellular respiration 3 steps in cellular respiration glycolysis Krebs cycle electron transport chain

Overview of Cellular Respiration cellular respiration: the process that releases energy by breaking down molecules in food in the presence of O2 aerobic: processes that require oxygen 6O2 + C6H12O6  6CO2 + 6H2O + Energy (heat) oxygen + glucose  carbon dioxide + water pyruvic acid produced in cytoplasm goes into mitochondria where further energy is released for ATP

Glycolysis one 6-carbon glucose molecule is broken in half to form two 3-carbon molecules of pyruvic acid Takes place in the cytoplasm ATP production two ATP molecules used between glucose and pyruvate while 4 ATP is made with pyruvic acid net gain of 2 ATP

NADH Production 4 high-energy electrons from pyruvate molecules and passed to 2 NAD+ (nicotinamide adenine dinucleotide) to form 2 NADH NADH used in other energy pathways in the cell to make ATP Glycolysis DOES NOT require O2

Glycolysis

Fermentation fermentation: a process in which cells release energy in the absence of oxygen converts NADH back to NAD+ by passing high-energy electrons back to pyruvic acid anaerobic: process does not require oxygen

Alcoholic Fermentation process used by yeast and a few other organisms to produce ethyl alcohol and CO2 pyruvic acid + NADH  alcohol + CO2 + NAD+ This process is used to make bread Bubbles of CO2 makes bread rise Small amount of alcohol evaporates during baking

Lactic Acid Fermentation Many cells convert accumulated pyruvic acid into lactic acid pyruvic acid + NADH  lactic acid + NAD+ Lactic acid produced in muscles during strenuous exercise when body cannot supply enough O2. This makes muscles sore.