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Metabolism. Chapter 24b. Metabolism. The sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc. Anabolism - build up of complex molecules Catabolism - break down of complex molecules. - PowerPoint PPT Presentation
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The sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc.
• Anabolism- build up of complex molecules
• Catabolism- break down of complex molecules
Metabolism
Fates of Organic Building Blocks in
ATP Metabolis
m
ORGANIC BUILDING BLOCK MOLECULESMonosaccharides
Amino acidsAcetates
Nucleotide bases
Polymers &
other energy
rich molecules
CO2
&H2O
anabolic processes
catabolic processes
ATP
ADP+Pi
energyenergy
Cellular RespirationC6H12O6 + 6O2 + 36ADP + 36Pi
6CO2 + 6H2O + 36ATP
Basic Steps Involved
Glycolysis
Krebs Cycle
Electron Transport System
Acetyl CoA Formation
1
2
3
4
Overview of Glycolysis
Other Other Metabolic Metabolic PathwaysPathways
FatsFats GlycogenGlycogen ProteinProtein
Glycolysis
Net:•2 ATP•2 NADH•2 Pyruvate molecules
2 pyruvate
Glucose
Cystol
NADH
NADH
ATP
ATP
ATP
ATP
ATPATP
NAD+
NAD+
P
P
ADP
ADP
ADP
ADP
ADP
ADP
P
P
P
P
H
H
Balance Sheet for Glycolysis
Input1 Glucose
4 ADP + Pi
2ATP
2 NAD+
Output2 Pyruvate
2 net ATP
2 NADH
NAD+ NAD+
ADPP ADPP
ATP ATP
NADH NADH
ATP ATP
Transition ReactionTransition Reaction
CO2
CoA
NADH+
NADH+H+
2 Acetyl CoA’s
2 pyruvates
3NAD+ +3H
Krebs Krebs CycleCycle
Transition ReactionTransition Reaction2 Acetyl CoA’s
2CO2
CoA
ATP
FADH2
FAD
3ADP+Pi
NADHNADHNADH
Krebs Cycle (Citric Acid Cycle)Krebs Cycle (Citric Acid Cycle)
Balance Sheet for the Balance Sheet for the Transition Reaction and Transition Reaction and
Krebs CycleKrebs CycleInput
2 Pyruvate2 ADP + 2 Pi
8 NAD+
2 FAD
Output6 CO2
2 ATP8 NADH2 FADH2
Krebs Cycle
Handles other substrates
Intermediate molecules used: proteins and lipids
Replenishment of intermediates necessary
Hans Krebs (1937): paper originally rejected
Krebs Cycle
Takes 2 complete cycles
8 steps, each with an enzyme
Krebs Cycle 3
Oxidative PhosphorylationOxidative Phosphorylation
ChemiosmosisElectrons are transferred from complex to complex and some of their energy is used to pump protons (H+) into the intermembrane space, creating a proton gradient.
ATP synthesis is powered by the flow of H+ back across the inner mitochondrial membrane through ATP synthase.
Each Glucose Molecule
CO2 6
NADH 10
FADH2 2
ATP 4
Electron Transport System
CO2 6
NADH 10
FADH2 2
ATP 4
used to make ATPused to make ATP
Electron Transport System 4
Electron Transport System
+Pi
Electron Transport Chain and Oxidative Phosphorylation
• Electrons are delivered to O, forming O–
• O– attracts H+ to form H2O
Figure 24.9
Glycolysis Krebscycle
Electron trans-port chain and oxidativephosphorylation
EnzymeComplex I
EnzymeComplex III
EnzymeComplex IV
EnzymeComplex II
NADH+H+
FADH2
Fre
e e
nerg
y r
ela
tive t
o O
2 (
kcal/
mol)
Electronic Energy Gradient
• Transfer of energy from NADH + H+ and FADH2 to oxygen releases large amounts of energy
• This energy is released in a stepwise manner through the electron transport chain
ATP Synthase
• Two major parts connected by a rod 1. Rotor in the inner mitochondrial
membrane
2. Knob in the matrix
• Works like an ion pump in reverse
Figure 24.11
Mitochondrial matrix
Intermembrane space
ADP+
A stator anchored in the membrane holds the knob stationary.
As the rotor spins, a rod connecting the cylindrical rotor and knob also spins.
The protruding, stationary knob contains three catalytic sites that join inorganic phosphate to ADP to make ATP when the rod is spinning.
A rotor in the membrane spins clockwise when H+
flows through it down the H+ gradient.
Net ATP Yield
34 to 36 molecules ATP for every glucose molecule
about 40% efficiencyabout 40% efficiency
ATP
Transition cycle
Overall ATP Production
Electron Transport System 34Citric Acid Cycle 2Glycolysis 2SUBTOTAL 38NADH Transport into Mitochondrion* -2TOTAL 36
Fermentation (Anaerobic Respiration)
Lactic Acid Fermentation
C
Glucose 2 Pyruvate 2 Lactic Acid
NAD+
NADH
NAD+
NADH
(Glycolysis) (Lactic acid fermentation)
C C C C C C C C C C C
Glucose
Pyruvateno
O2 O
2
Acetyl CoAEthanol or
LactateKrebs Cycle
Anaerobic Respiration
Aerobic Respiration
INQUIRY1. What is the end product in glycolysis?2. What substance is produced by the
oxidation of pyruvate and feeds into the citric acid cycle?
3. Name a product of fermentation.4. What role does O2 play in aerobic
respiration?5. What stage during cellular respiration is the
most ATP synthesized?6. What is chemiosmosis?7. When NAD+ and FAD+ are reduced what
do they form?8. What are they used for?
