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Aerobic Respiration. Only occur in the presence of oxygen Two stages Krebs Cycle Electron Transport Chain with chemiosmosis Prokaryotes Occur in cytosol Eukaryotes Occur in mitochondria. Aerobic Respiration. After glycolysis, pyruvic acids are produced
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Aerobic Respiration • Only occur in the presence of oxygen • Two stages • Krebs Cycle • Electron Transport Chain • with chemiosmosis • Prokaryotes • Occur in cytosol • Eukaryotes • Occur in mitochondria
Aerobic Respiration • After glycolysis, pyruvic acids are produced • Pyruvic acid moves inside mitochondria into mitochondrial matrix (space between two membranes) • Pyruvic acid + CoA Acetyl CoA + CO2
The Krebs Cycle • Acetyl CoA CO2 + H + ATP • The H produced reduce NAD+ NADH • Five steps in the Krebs Cycle • Occurs in mitochondrial matrix • Citric Acid is made in Step 1 therefore this is also called the Citric Acid cycle • Net ATP produced is 2 ATP
Krebs Cycle - Step 1 • Acetyl CoA + oxaloacetic acid Citric Acid • This step releases CoA back into the mitochondrial matrix for pyruvic acid to be fixed again
Krebs Cycle – Step 2 • Citric acid releases CO2 and H • Becomes a 5-carbon compound • The H released, reduces the NAD+ to NADH
Krebs Cycle – Step 3 • Five carbon compound releases another CO2 and H • Becomes a 4 carbon compound • Another NAD+ is reduced to NADH • Produces an ATP
Krebs Cycle – Step 4 • 4 carbon compound releases H atom • This time, FAD is reduced to FADH2 • Similar molecule to NAD+
Krebs Cycle – Step 5 • 4 carbon compound releases H atom • Reduces NAD+ to NADH • This reaction regenerates initial oxaloacetic acid
Electron Transport Chain • Uses the high-energy e- from the Krebs Cycle to convert ADP to ATP • Total net ATP produced is 34!! • Prokaryotes • Occurs on cell membrane of organism • Eukaryotes • Occurs in the mitochondria membrane called cristae
ETC – Step 1 • NADH & FADH2 are used to power this chain of reactions • NADH & FADH2 are oxidized (lose e-) to the electron transport chain • Also donate H atoms • NADH NAD+ • FADH2 FAD+
ETC – Step 2 • Electrons from NADH & FADH2 are passed down chain • Lose some energy each time passed on
ETC – Step 3 • Lost energy from e- transferring down the chain pump protons (H+) • This creates high conc. of H+ between inner and outer membranes • Creates a concentration gradient & electrical gradient since H+ are positive
ETC – Step 4 • Concentration & electrical gradient in membranes produce ATP molecules by chemiosmosis • ATP synthase is protein embedded in membrane that pumps protons out and creates ATP
ETC – Step 5 • The electrons move to final acceptor down the chain • Oxygen is the final acceptor • Oxygen also accepts protons provided by NADH & FADH2 • The protons, electrons, and oxygen all combine to produce H2O
Importance of Oxygen • The only way to produce ATP is by the movement of electrons in the ETC • Oxygen is the final acceptor • Without oxygen, the ETC would halt
Efficiency of Aerobic Respiration • Glycolysis = 2 ATP • Krebs Cycle = 2 ATP • ETC = 34 ATP • Total = 38 ATP!!
Efficiency Equation • Depends on conditions of the cell • How ATP are transported • Cellular respiration is 20 times more efficient than glycolysis
Summary • Cellular respiration • Glycolysis • Glucose pyruvic acid + ATP + NADH • Aerobic respiration • Pyruvic acid CO2 + H2O + ATP
Energy & Exercise • Quick energy – Lactic Acid fermentation is used to get quick energy and gives off lactic acid as a by product, thus the muscle pain. • Long-Term Energy – Use cellular respiration to produce energy. Exercising or activities that last for at least 15 to 20 minutes. Best form for weight control.
