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Chapter 9.3. Getting Energy to Make ATP. Cellular Respiration. Cellular respiration – The process by which food molecules are broken down to produce ATP. The reaction: C 6 H 12 0 6 + 6 O 2 → 6 CO 2 + 6 H 2 O + ATP. Aerobic vs. Anaerobic. ATP can be made aerobically or anaerobically.
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Chapter 9.3 Getting Energy to Make ATP
Cellular Respiration • Cellular respiration – The process by which food molecules are broken down to produce ATP. • The reaction: C6H1206 + 6 O2→ 6 CO2 + 6 H2O + ATP
Aerobic vs. Anaerobic • ATP can be made aerobically or anaerobically. • Aerobic – requires oxygen • Anaerobic – does not require oxygen
3 Stages of Cellular Resp. • Glycolysis – anaerobic; takes place in cytoplasm. • Krebs (citric acid) cycle – aerobic; takes place in mitochondrion. • Electron transport chain – aerobic; takes place in mitochondrion.
Cellular respiration Cytosol (Inside a cell) Mitochondrion 2. Citric acid cycle 1. Glycolysis STEP STEP ATP STEP Glucose 2 ATP,NADH,FADH2 3. Electron transport(yields 32 ATP) Acetyl-CoANADH Pyruvic acidNADH2 ATP
A Mitochondrion Intermembrane space Outer membrane Inner membrane Matrix
Electron Transport • Electron transport chain (ETC) – series of proteins embedded in the inner mitochondrial membrane. • Electron carriers give up electrons to the ETC which are used to establish a proton gradient (high concentration in the intermembrane space, low in the matrix). • The proton gradient is used to produce ATP (just like in photosynthesis). • Oxygen is the final electron acceptor.
More details of the electron transport chain High concentration of protonspH ~7 Intermembranespace Electron flow III I II IV Innermembrane Matrix ATP synthase Electrons ATP NADH NAD+ Pi Low concentration of protonspH ~8 ADP STEP 4: ELECTRON TRANSPORT CHAIN
Chemiosmosis • Chemiosmosis – using the electrochemical gradient (ion concentration and pH) built up by the electron transport chain to synthesize ATP. • Electron transport produces 32 ATP (per molecule of glucose). • How many molecules ATP are produced by glycolysis and the Krebs cycle?
Aerobic ATP Production • Glycolysis – nets 2 molecules of ATP per molecule of glucose • Citric Acid Cycle – 2 ATPs per glucose • Electron Transport – 32 ATPs per glucose
Anaerobic ATP Production • Glycolysis – 2 ATP molecules • If no oxygen is available, glycolysis is followed by either lactic acid fermentation or alcoholic fermentation. • Fermentation produces no ATP; only allows NADH (an electron carrier) to be restored to NAD+.
Fermentation • Your cells produce lactic acid in the absence of oxygen. • Bacteria and yeast produce ethanol and carbon dioxide in the absence of oxygen
Two kinds of fermentaion 2 NAD+ 2 H2O 2 NAD+ Glucose Acetaldehyde Pyruvate Ethanol Glycolysis 2 NADH 2 NADH 2 CO2 2 ATP
Two kinds of fermentation (continued) 2 NAD+ 2 NAD+ Lactic acid Pyruvate Glycolysis Glucose 2 NADH 2 NADH 2 ATP
Metabolism consists of two pathways Carbohydrates, fats,proteins in food Digestion Simple molecules: glucose, fatty acids,amino acids ATP ATP consumed produced Further breakdown to produce ATP, CO2, and H2O Production of largemolecules
How do other food molecules enter metabolism? FATS AND OILS Glycerol, fatty acids Acetyl-CoA Electrontransport Pyruvate Glucose Glucose Glycolysis Citric acid cycle CARBOHYDRATES Amino acids PROTEINS