Cellular Respiration
Photosynthesis provides C for plant
metabolism: Starch and Sucrose
Interchanging of this C through the
hexose-phosphate pool feeds many
metabolic pathways
Carbohydrates (6-C sugars) are the
MAJOR source of energy for cell
Cells break down glucose (sugar) to
make ATP “energy”
C6H12O6 + 6O2  6CO2 + 6H2O + usable energy (ATP)
Cellular Respiration (3-stages)
Glycolysis
Krebs Cycle (Citric Acid Cycle)
Electron Transport Chain (ETC)
Glucose
Glycolysis
Krebs
cycle
Fermentation
(without oxygen)
Electron
transport
Alcohol or
lactic acid
Flowchart
Section 9-2
Cellular Respiration
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
+
ATP
Figure 9–3 Glycolysis
Glycolysis:
Step 1
Glucose
2 Pyruvic acid
To the electron
transport chain
Where Cytoplasm
NO O2 required
Energy Yield net gain of 2 ATP at the
expense of 2 ATP
6-C glucose  TWO 3-C pyruvates
Free e- and H+ combine with organic ion
carriers called NAD+  NADH + H+
(nicotinamide dinucleotide)
Summary
In
Glucose (6-C)
2 ATP
Out
2 pyruvate; 2(3-C)
2NADH
a net of 2 ATP
Figure 9–6 The Krebs Cycle
Section 9-2
Citric Acid
Production
Mitochondrion
Breakdown of Pyruvic Acid
Where
mitochondria
Pyruvate (3-C) 
Acetic acid (2-C)
3rd C forms CO2
Acetic acid
combines with
Coenzyme A to
form ACETYL-CoA
Summary
In
Pyruvate
NAD
CoA
Out
CO2 (as waste)
NADH
Acetyl-CoA
Second Step: Citric Acid Cycle
(Krebs Cycle)
Where Mitochondrial matrix
Energy Yield 2 ATP and more eAcetyl-CoA (2-C) combines with 4-C to form
6-C CITRIC ACID
Citric Acid (6-C) changed to 5-C then to a 4-C
Gives off a CO2 molecule
NAD+ and FAD pick up the released eFAD becomes FADH2
NAD+ becomes NADH + H+
Cycle ALWAYS reforming a 4-C molecule
Krebs Cycle
ETC
Where inner membrane of
mitochondria
Energy Yield Total of 32 ATP
O2 combines with TWO H+ to form
H 2O
Exhale - CO2, H2O comes from
cellular respiration
Electron Transport Chain
Section 9-2
Electron Transport
Hydrogen Ion Movement
Channel
Mitochondrion
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production
Summary
Mitochondrion
Electrons carried in NADH
Pyruvic
acid
Glucose
Glycolysis
Krebs
Cycle
Electrons
carried in
NADH and
FADH2
Electron
Transport
Chain
Mitochondrion
Cytoplasm
Total ENERGY Yield
Glycolysis 2 ATP
Krebs Cycle 2 ATP
ETC  32 ATP
Total 36 ATP
What happens if NO O2?
Cellular respiration process STOPS
Aerobic vs. Anaerobic
Anaerobic
DOES NOT
require oxygen
Simple
fast
produces
smaller amounts
of energy (ATP)
Aerobic requires
oxygen
Yields large
amounts of energy
(ATP)
Releasing Energy without Oxygen
Anaerobic Respiration
NO Additional ATP is Formed
NO O2 leads to Fermentation
Two Types
Lactic Acid Fermentation
Alcoholic Fermentation
Lactic Acid Fermentation
bacteria, plants and most animals
After glycolysis
2 pyruvic acid changed to lactic acid
Alcoholic Fermentation
Bacteria and fungi (yeast)
Ethyl alcohol and carbon dioxide are
the end products
Process used to form beer, wine, and
other alcoholic beverages
Also used to raise dough, bread
Cellular Respiration Review
Three Main Stages
Glycolysis (2 ATP)
Kreb’s Cycle (2 ATP)
Electron Transport Chain (32 ATP)
July 31, 2017