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
Jan 13, 2016
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.
Comparing Photosynthesis & Respiration
Photosynthesis Cellular Respiration
Function Energy Storage Energy Release
Location Chloroplasts Mitochondria
Reactants CO2 and H2O C6H12O6 and O2
Products C6H12O6 and O2 CO2 and H2O
Equation 6CO2 + 6H2O C6H12O6 + 6O2
C6H12O6 + 6O2
6CO2 + 6H2O