Cellular Respiration
1
Cellular Respiration
A catabolic, exergonic, oxygen (O2) requiring process that
uses energy extracted from macromolecules (glucose) to
produce energy (ATP) and water (H2O).
C6H12O6 + 6O2  6CO2 + 6H2O + energy
glucose
ATP
2
Question:
In what kinds organisms does cellular respiration
take place?
3
Plants and Animals
Plants - Autotrophs: self-producers.
Animals - Heterotrophs: consumers.
4
Mitochondria
Organelle where cellular respiration takes place.
Outer
membrane
Inner
membrane space
Matrix
Cristae
Inner
membrane
5
Redox Reaction
Transfer of one or more electrons from one
reactant to another.
Two types:
1.
Oxidation
2.
Reduction
6
Oxidation Reaction
The loss of electrons from a substance.
Or the gain of oxygen.
Oxidation
C6H12O6 + 6O2 6CO2 + 6H2O + energy
glucose
ATP
7
Reduction Reaction
The gain of electrons to a substance.
Or the loss of oxygen.
Reduction
C6H12O6 + 6O2 
glucose
6CO2 + 6H2O + energy
ATP
8
Breakdown of Cellular Respiration
Four main parts (reactions).
1. Glycolysis (splitting of sugar)
a. cytosol, just outside of mitochondria.
2. Grooming Phase
a. migration from cytosol to matrix.
9
Breakdown of Cellular Respiration
3. Krebs Cycle (Citric Acid Cycle)
a. mitochondrial matrix
4. Electron Transport Chain (ETC) and
Oxidative Phosphorylation
a. Also called Chemiosmosis
b. inner mitochondrial membrane.
10
1. Glycolysis
Occurs in the cytosol just outside of
mitochondria.
Two phases (10 steps):
A. Energy investment phase
a. Preparatory phase (first 5 steps).
B. Energy yielding phase
a. Energy payoff phase (second 5 steps).
11
1. Glycolysis
A. Energy Investment Phase:
Glucose (6C)
2ATP
C-C-C-C-C-C
2 ATP - used
0 ATP - produced
0 NADH - produced
2ADP + P
Glyceraldehyde phosphate (2 - 3C)
(G3P or GAP)
C-C-C
C-C-C
12
1. Glycolysis
B. Energy Yielding Phase
Glyceraldehyde phosphate (2 - 3C)
(G3P or GAP)
4ADP + P
4ATP
GAP
GAP
C-C-C C-C-C
0 ATP - used
4 ATP - produced
2 NADH - produced
Pyruvate (2 - 3C)
(PYR)
C-C-C C-C-C
(PYR) (PYR)
13
1. Glycolysis
Total Net Yield
2 - 3C-Pyruvate (PYR)
2 - ATP (Substrate-level Phosphorylation)
2 - NADH
14
Substrate-Level Phosphorylation
ATP is formed when an enzyme transfers a
phosphate group from a substrate to ADP.
Enzyme
Example:
PEP to PYR
Substrate
(PEP)
Product
(Pyruvate)
OC=O
C-OCH2
OC=O
C=O
CH2
P
P
P
Adenosine
ADP
P P
P
Adenosine
ATP
15
Fermentation
Occurs in cytosol when “NO Oxygen” is present (called
anaerobic).
Remember: glycolysis is part of fermentation.
Two Types:
1.
Alcohol Fermentation
2. Lactic Acid Fermentation
16
Alcohol Fermentation
Plants and Fungi 
C
C
C
C
C
C
glucose
2ADP
+2 P
2ATP
2NADH
C
C
C
Glycolysis
2 NAD+
beer and wine
2NADH
2 Pyruvic
acid
2 NAD+
C
C
2 Ethanol
2CO2
released
17
Alcohol Fermentation
End Products: Alcohol fermentation
2 - ATP (substrate-level phosphorylation)
2 - CO2
2 - Ethanol’s
18
Lactic Acid Fermentation
Animals (pain in muscle after a workout).
C
C
C
C
C
C
2ADP
+2 P
2ATP
2NADH
C
C
C
Glycolysis
2 NAD+
2NADH
2 Pyruvic
acid
2 NAD+
C
C
C
2 Lactic
acid
Glucose
19
Lactic Acid Fermentation
End Products: Lactic acid fermentation
2 - ATP (substrate-level phosphorylation)
2 - Lactic Acids
20
2. Grooming Phase
Occurs when Oxygen is present (aerobic).
2 Pyruvate (3C) molecules are transported through the
mitochondria membrane to the matrix and is converted
to 2 Acetyl CoA (2C) molecules.
Cytosol
2 CO2
C
C
C
Matrix
C-C
2 Pyruvate
2 NAD+
2NADH
2 Acetyl CoA
21
2. Grooming Phase
End Products: grooming phase
2 - NADH
2 - CO2
2- Acetyl CoA (2C)
22
3. Krebs Cycle (Citric Acid Cycle)
Location: mitochondrial matrix.
Acetyl CoA (2C) bonds to Oxalacetic acid (4C OAA) to make Citrate (6C).
It takes 2 turns of the krebs cycle to oxidize 1
glucose molecule.
Mitochondrial
Matrix
23
3. Krebs Cycle (Citric Acid Cycle)
1 Acetyl CoA (2C)
OAA (4C)
Citrate (6C)
FADH2
Krebs
Cycle
2 CO2
(one turn)
3 NAD+
FAD
3 NADH
ATP
ADP + P
24
3. Krebs Cycle (Citric Acid Cycle)
2 Acetyl CoA (2C)
Citrate (6C)
OAA (4C)
2 FADH2
Krebs
Cycle
4 CO2
(two turns)
6 NAD+
2 FAD
6 NADH
2 ATP
2 ADP +
P
25
3. Krebs Cycle (Citric Acid Cycle)
Total net yield (2 turns of krebs cycle)
1.
2 - ATP (substrate-level phosphorylation)
2.
6 - NADH
3.
2 - FADH2
4.
4 - CO2
26
4. Electron Transport Chain (ETC) and
Oxidative Phosphorylation (Chemiosmosis)
Location: inner mitochondrial membrane.
Uses ETC (cytochrome proteins) and ATP Synthase
(enzyme) to make ATP.
ETC pumps H+ (protons) across innermembrane (lowers
pH in innermembrane space).
Inner
Mitochondrial
Membrane
27
4. Electron Transport Chain (ETC) and
Oxidative Phosphorylation (Chemiosmosis)
The H+ then move via diffusion (Proton Motive Force)
through ATP Synthase to make ATP.
All NADH and FADH2 converted to ATP during this stage of
cellular respiration.
Each NADH converts to 3 ATP.
Each FADH2 converts to 2 ATP (enters the ETC at a lower
level than NADH).
28
4. Electron Transport Chain (ETC) and
Oxidative Phosphorylation (Chemiosmosis)
Outer
membrane
Inner
membrane space
Matrix
Cristae
Inner
membrane
29
4. ETC and Oxidative Phosphorylation (Chemiosmosis for
NADH)
higher H+
concentration
Intermembrane Space
1H+
E
2H+
3H+
T
C
NAD+
(Proton Pumping)
Matrix
ATP
Synthas
e
Inner
Mitochondrial
Membrane
O2 H O
2
2H+ + 1/2
NADH
+ H+
H+
ADP + P
H+
ATP
lower H+
concentration
30
4. ETC and Oxidative Phosphorylation (Chemiosmosis for
FADH2)
higher H+
concentration
Intermembrane Space
1H+
E
T
FADH2
+ H+
FAD+
(Proton Pumping)
Matrix
2H+
C
2H+ +
1/2O2
H+
ATP
Synthas
e
Inner
Mitochondrial
Membrane
H2O
ADP + P
H+
ATP
lower H+
concentration
31
TOTAL ATP YIELD
1. 04 ATP - substrate-level phosphorylation
2. 34 ATP - ETC & oxidative phosphorylation
38 ATP - TOTAL YIELD
ATP
32
Eukaryotes
(Have Membranes)
Total ATP Yield
02 ATP - glycolysis (substrate-level phosphorylation)
04 ATP - converted from 2 NADH - glycolysis
06 ATP - converted from 2 NADH - grooming phase
02 ATP - Krebs cycle (substrate-level phosphorylation)
18 ATP - converted from 6 NADH - Krebs cycle
04 ATP - converted from 2 FADH2 - Krebs cycle
36 ATP - TOTAL
33
Maximum ATP Yield for Cellular Respiration
(Eukaryotes)
Glucose
Cytosol
Glycolysis
2 Acetyl CoA
2 Pyruvate
Mitochondria
Krebs
Cycle
2NADH
2 ATP
6NADH
2FADH2
(substrate-level
phosphorylation)
2NADH
ETC and Oxidative
Phosphorylation
2 ATP
(substrate-level
phosphorylation)
2ATP
4ATP 6ATP
18ATP
4ATP
36 ATP (maximum per glucose)
2ATP
34
Prokaryotes
(Lack Membranes)
Total ATP Yield
02 ATP - glycolysis (substrate-level phosphorylation)
06 ATP - converted from 2 NADH - glycolysis
06 ATP - converted from 2 NADH - grooming phase
02 ATP - Krebs cycle (substrate-level phosphorylation)
18 ATP - converted from 6 NADH - Krebs cycle
04 ATP - converted from 2 FADH2 - Krebs cycle
38 ATP - TOTAL
35
Question:
In addition to glucose, what other various food
molecules are use in Cellular Respiration?
36
Catabolism of Various
Food Molecules
Other organic molecules used for fuel.
1. Carbohydrates: polysaccharides
2. Fats: glycerol’s and fatty acids
3. Proteins: amino acids
37