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