1. Cellular Respiration
Process where living organisms convert the energy in glucose into usable cellular energy (ATP)
Too much energy in glucose to be released at once, needs to be converted into smaller ATP molecules
High energy C-C & C-H bonds converted into C-O & O-H bonds
Each glucose can be broken down to form 36 or 38 ATP
Only 36% of energy in glucose is converted to ATP; rest is lost as heat (a car uses ~25% of energy from fuel)

2. Cellular Respiration
Glycolysis is the first stage of respiration and occurs in the cytoplasm of the cell
Glycolysis (Glyco= sweet; lysis= to cut)
Splits Glucose (6 carbons) into 2 Pyruvic Acid (3 carbons)
Does NOT need O2 to occur
Uses 2 ATP to start; makes 4 ATP and NADH
Controlled by an allosteric enzyme – 2 active sites; allosteric effector (ATP) must attach first to change the shape of the 2nd active site

3. Cellular Respiration 2 Types of Cellular Respiration:
1. Anaerobic Respiration (aka: Fermentation)
Occurs without O2
Occurs in the cytoplasm
Uses pyruvic acid from glycolysis
Enzymes required
Makes 2 ATP per glucose
A) Alcohol Fermentation – creates ATP, alcohol, & CO2
Ex: Yeast
B) Lactic Acid Fermentation – creates ATP, CO2, & lactic acid
Ex: Muscle cells

4. Cellular Respiration 2. Aerobic Respiration Krebs Cycle
Occurs with O2 in the mitochondria
95% of a cells energy is through aerobic pathway
Also uses pyruvic acid from glycolysis
Creates 34 ATP per glucose
Enzymes required for the Krebs Cycle
Chemical reaction: O2 + C6H12O ATP + CO2 + H2O
2 Stages:
Krebs Cycle
Electron Transport Chain (E.T.C.)

5. Cellular Respiration Krebs Cycle (aka: Citric Acid Cycle):
Pyruvic acid reacts with coenzyme A to form acetyl coenzyme A (acetyl CoA)
Krebs Cycle (aka: Citric Acid Cycle):
Occurs in the mitochondrial matrix
Acetyl CoA goes into the Krebs Cycle
Acetyl CoA combines with Oxaloacetic acid to create Citric Acid
Citric acid is made into a 5-carbon compound; produces CO2 and NADH
As a 4-carbon compound is produced, another CO2 and 2 ATP are made
FADH2 is produced
4-Carbon molecule is made back into oxaloacetic acid to restart cycle

6. Cellular Respiration Electron Transport Chain:
Occurs in the inner membrane of the mitochondria
NADH & FADH2 made in previous steps give up electrons and H+
Electrons are passed down the chain, pumping H+ across the membrane
H+ move back to the other side through ATP Synthase and ATP is produced (32 ATP)
O2 accepts H+ and forms H2O