Begins with Glycolysis Aerobic Respiration Chapter 7-2 Organic compounds are broken down to release energy, as in ATP! Begins with Glycolysis If no oxygen = fermentation - lactic acid - alcoholic If oxygen = aerobic respiration 1. Kreb's cycle 2. Electron transport

Overview Aer. Resp. produces 20 X more ATP than glycolysis Aer. Resp.: Most cells go through aerobic respiration instead of fermentation! (When Oxygen is present) Aer. Resp. produces 20 X more ATP than glycolysis Aer. Resp.: - takes place in the mitochondria of eukaryotes and the cytosol of prokaryotes - Pyruvic acid enters the mitochondrial matrix and reacts with coenzyme A to make Acetyl CoA (releasing a CO2) - two steps 1. Kreb’s Cycle 2. Electron transport chain

The Kreb’s Cycle: a biochemical pathway that breaks down Acetyl CoA, producing CO2, H, and ATP.

5 Steps of the Kreb’s cycle: Use pg. 134 to summarize the steps. 1. 2. 3. 4. 5.

The Kreb’s Cycle doesn’t make much ATP, but it does make something used in the next stage that will produce a lot of ATP. What does it make? (Hint: see pg. 136) 1. 2. aerobic respiration

Electron Transport Chain Second step of aerobic respiration Occurs in the cristae (inner membrane of mitochondria) of eukaryotes (and cell membrane in prokaryotes) Same process as in photosynthesis, but different molecules - electrons move through a series of molecules and lose energy - that energy is used to pump protons which drives the synthesis of ATP - ATP synthase converts ADP to ATP (chemiosmosis) - Final electron acceptor is oxygen (this allows more ATP and water to be made) 7-2 http://highered.mcgraw-hill.com/olc/dl/120071/bio11.swf

For a cell that generates 38 molecules: Energy Yield Efficiency of aer. Resp. = Energy required for ATP Energy released For a cell that generates 38 molecules: 38 x 12 kcal X 100% = 66% 686 kcal Compared to Glycolysis alone, aerobic respiration is 20 times more efficient than glycolysis alone!

Section 7-2 Review What four-carbon compound is regenerated at the end of the Krebs cycle? With what two-carbon compound does it combine at the start of the Krebs cycle? How is the synthesis of ATP in the electron transport chain of mitochondria similar to the synthesis of ATP in chloroplasts? What role does oxygen play in aerobic respiration? What molecule does oxygen become a part of as a result of aerobic respiration? In what part of a mitochondrion does the Krebs cycle occur? In what part of a mitochondrion is the electron transport chain located? Calculate the efficiency of aerobic respiration if a cell generates 32 ATP molecules per molecule of glucose.