Chapter 9:Cellular Respiration& Fermentation
ATP & Energy
I. Structure of ATPA. ATP (Adenosine Triphosphate) – shuttles energy
for cellsB. ATP is composed of ribose (a sugar), adenine (a
nitrogenous base), and three phosphate groups
II. ATP & EnergyA. The bond between the terminal phosphate
groups of ATP’s can be broken, releasing organic phosphate and leaving ADP (adenosine diphosphate).
B. Energy is released from ATP when the terminal phosphate bond is broken.
C. This release of energy comes from the chemical change to a state of lower free energy (stabilizing), not from the phosphate bonds themselves.
Glycolysis & FermentationI. Harvesting Chemical Energy
A. Cellular Respiration – the break down of organic compounds (food, glucose, etc.) in cells to make energy, ATP molecules
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
B. Glycolsysis 1. Biochemical pathway that always starts
cellular respiration!!!2. Does produce a small amount of ATP.3. Other products can follow two other
pathways, depending on whether oxygen is present not.
Glycolysis ATP
Oxygen Absent Oxygen Present
Fermentation(anaerobic) Aerobic
Respiration
ATP
C. Two (2) Types of Cellular Respiration1. Anaerobic Respiration – respiration without
oxygen– Also called fermentation
2. Aerobic Respiration – respiration with oxygen
II. Glycolysis
A. Basics of Glycolysis 1. glyco: sugar lysis: break up
• Begins to break down glucose & releases a small amount of energy (ATP)
2. Occurs in the cytoplasm.3. All types of cellular respiration begin with
glycolysis!!!!!!!!!!
B. Major events in Glycolysis1. Start with (invest) 1 glucose, 2 NAD+, and 2 ATP
molecules.2. Glucose, a 6-carbon molecule, is split into 2 PGAL,
or glyceraldehyde-3-phosphate, molecules (each a 3-carbon molecule).
3. Hydrogens are transferred from the 2 PGAL molecules to the 2 NAD+ molecules. This produces 2 NADH molecules.
4. 4 ATP molecules are then produced (2 ATP overall). This also produces 2 pyruvic acid molecules.
5. Ends with 2 pyruvic acid, 2 ATP, 2 NADH molecules.
Glycolysis
III. Anaerobic Respiration
A. Basics1. Also known as Fermentation2. Does not make any ATP!3. Does remake NAD+, which goes back through
Glycolysis to make 2 more ATP.
B. 2 Types of Fermentation1. Lactic Acid Fermentation
• 2 H+ are removed from 2 NADH to make NAD+.• Pyruvic acid is converted into lactic acid by
gaining the 2 H+.• NAD+ goes back through glycolysis to make
more ATP.
(b) Lactic acid fermentation
2 Lactate
2 Pyruvate
2 NADH
Glucose Glycolysis
2 ADP 2 P i 2 ATP
2 NAD
2 H
Figure 9.17b
2. Alcoholic Fermentation• A CO2 molecule is removed from each pyruvic
acid, creating acetaldehyde.• 2 H+ are removed from 2 NADH to make NAD+.• Acetaldehyde is converted into ethyl alcohol by
gaining the 2 H+.• NAD+ goes back through glycolysis to make
more ATP.
2 ADP 2 P i 2 ATP
Glucose Glycolysis
2 Pyruvate
2 CO22 NAD
2 NADH
2 Ethanol 2 Acetaldehyde
(a) Alcohol fermentation
2 H
Figure 9.17a
IV. Mitochondria ReviewA. Structure
1. Surrounded by a double membrane2. The 2nd, inner membrane, is highly folded to
increase surface area. Each fold is called a cristae
3. The very interior of the mitochondria is called the mitochondrial matrix.
IV. Aerobic Respiration
A. Basics1. Aerobic Respiration requires oxygen (O2)!
2. Produces nearly 20 times more ATP than glycolysis alone.
3. Begins with Glycolysis, followed by the Kreb’s Cycle, the Electron Transport Chain, and Chemiosmosis.
B. Glycolysis 1. Converts glucose into 2 pyruvic acids.2. Makes 2 NADH and a net of 2 ATP.3. Occurs in the cytoplasm
C. Pyruvic acid is converted into Acetyl CoA.1. The 2 Pyruvic Acids pass through both
mitochondrial membranes into the mitochondrial matrix.
2. As this happens, the 2 pyruvic acids reacts with a molecule called coenzyme A to form Acetyl CoA.
3. 2 NADH’s and CO2 are produced.
D. Kreb’s Cycle1. Each Acetyl CoA is broken down to make 1 ATP, 3
NADH, and 1 FADH2.
2. 1st product is remade in the last step, so the Kreb’s Cycle can happen again.
3. Remember, there are 2 Acetyl CoA’s, so the Kreb’s cycle will happen twice.
4. Our totals are therefore: 2 ATP, 6 NADH, and 2 FADH2.
NADH
1
Acetyl CoA
CitrateIsocitrate
-Ketoglutarate
SuccinylCoA
Succinate
Fumarate
Malate
Citricacidcycle
NAD
NADH
NADH
FADH2
ATP
+ H
+ H
+ H
NAD
NAD
H2O
H2O
ADP
GTP GDP
P i
FAD
3
2
4
5
6
7
8
CoA-SH
CO2
CoA-SH
CoA-SH
CO2
Oxaloacetate
E. Electron Transport Chain1. Occurs across the inner membrane of the
mitochondria (cristae).2. H+ ions are released from NADH and FADH2 into
the mitochondrial matrix.3. The electrons in the hydrogen atoms are at a
high energy level! 4. The high energy electrons are passed along a
series of molecules called the Electron Transport Chain.
E. Electron Transport Chain (cont.)5. As the electrons move from molecule to
molecule, they lose some of their energy.6. This energy pumps H+ out of the mitochondrial
matrix, into the space between the two mitochondrial membranes.
7. A high concentration of H+ builds up in this space.
Electron Transport Chain
F. Chemiosmosis1. H+ ions diffuse from the high area of
concentration made in between the 2 mitochondrial membranes to the low are in the matrix.
2. Specifically the H+ ions move through a protein called ATP Synthase.
3. As H+ ions move through ATP Synthase, ATP is made!
4. 34 ATP are made in chemiosmosis.5. The H+ ions then combine with oxygen to form
water.
Electron Transport Chain
Summary of Aerobic Respiration
Total ATP made aerobically: 38 ATP’sGlycolysis = 2Kreb’s Cycle = 2Electron Transport Chain = 34