CH. 7 - HOW CELLS HARVEST ATP
I. 4 STEPS OF ATP PRODUCTION - (use handout) (p. 126)
A. GLYCOLYSIS - sugar breakdown.
B. PYRUVATE OXIDATION = BRIDGE STEP - Pyruvic Acidèacetyl CoA
C. KREBS CYCLE - AKA the citric acid cycle.
D. ELECTRON TRANSPORT CHAIN.
II. 5 THINGS TO LOOK AT FOR EACH STEP
1. Reactants
2. Products
3. Location
4. Energy production
5. O2 requirement
A. GLYCOLYSIS (p. 127-130)
1. Reactants - Glucose (6C)
2. Products - 2 Pyruvic acids (P.A.) (3C)
3. Location - cytoplasm
4. Energy - 2 ATP molecules, 2NADH + H+ (protons).
5. No O2 required.
B. PYRUVATE OXIDATION = "BRIDGE STEP" (p. 130)
1. Reactants - 2 pyruvic acids (3C)
2. Products - 2 acetyl CoA (2C) + 2CO2 as a waste.
3. Location - mitochondria.
4. Energy - No ATP. 2NADH (electron carrier) + H+ (protons)
5. O2 used - indirectly
C. KREBS CYCLE (CITRIC ACID CYCLE) (p. 131 - 133)
1. Reactants - Oxaloactic Acid (4C) + Acetyl group (2C)è
Citric acid (6C). Acetyl group is the reactant.
2. Products - 2CO2 per turnè 4CO2.
3. Location - mitochondria.
4. Energy - each acetyl groupè (3NADH + H+ +1 FADH2 +1ATP) X 2
5. O2 required - indirectly
D. ELECTRON TRANSPORT CHAIN (ETC) (p. 134 - 136)
1. Reactants - a.10 NADH and 2 FADH2 go into the ETC.
b. O2 as final e- acceptor
c. H+ used in chemiosmosis
2. Products - NAD+, FAD & H2O
3. Location - mitochondria
4. Energy - Each NADH X 3 ATP è 30 ATP
Each FADH2 X 2 ATP è 4 ATP = 34 ATP
5. O2 required - directly
E. SUMMARY OF ENERGY PRODUCTION FROM 1 GLUCOSE (p. 137)
1. Use worksheet.
2. 38 - 2 ATP (to get NADH from glyco. into mito.) 36 ATP
3. C6H12O6 + 6O2 è 6CO2 + 6H2O + energy (36 ATP)
4. 34/36 ATP (95%) made aerobically (w/ O2)
5. Yet, we only extract 38% of available energy from glucose
6. 62% lost as heat to envt.
7. Automobiles only 25% efficient.
F. THERMOREGULATION
1. Homeothermic/Endothermic
a. generate heat internally = warm-blooded
b. fur/feathers/fat - can regulate body heat
2. Poikilothermic/Ectothermic
a. get heat externally = cold-blooded.
b. can't regulate body heat
III. ANAEROBIC METABOLISM - no O2 (p. 129 & 140)
A. PLANTS = FERMENTATION - incomplete glucose combustion
1. Glucose è 2 pyruvic acids è ethanol (alcohol)
2. Alcohol at 12-18% kills yeast
B. ANIMALS
1. Glucose è 2 pyruvic acid è lactic acid
2. Burning in muscles after rigorous exercise = O2 debt
IV. CHEMIOSMOSIS
A. MITOCHONDRIA STRUCTURE - (p. 74; 134 - 136) transparency
1. Outer membrane
2. Inner membrane
3. Intermembrane space - between inner & outer membranes
4. Cristae - folds
5. Matrix - Innermost compartment
B. ETC (p. 136)
1. NADH & FADH2 stripped of e- & H+
2. e- passed through ETC
3. H+ pumped from matrix to intermembrane space by
energy of e- moving along ETC
C. PROTON (H+) GRADIENT (p. 136)
1. Across inner membrane
2. Potential energy, like a dam or a battery
Matrix Intermembrane Space
a. Lo [H+] Hi [H+] Concentration gradient
b. Basic Acidic pH gradient
c. Negative Positive Voltage gradient
3. H+ can't get back through, even though they want to!
D. OXIDATIVE PHOSPHORYLATION - requires O2
1. ATP synthase "channel"
2. Protons flow through, provide energy to phosphorylate ADP
3. ADP + Pi è ATP
4. “Used” e- combine with H+ that pass thru ATP synthase
to form H2O!
V. ENERGY FROM OTHER NUTRIENTS (p. 141)