Download Cellular Respiration

Cellular Respiration
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Obtain energy from the degradation of sugars
Uses Oxygen and produces CO2
Many steps take place in the mitochondria of
cells
Complementary process to photosynthesis
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Will recognize many of the same molecules
Oxidation-Reduction reactions
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Type of reaction when an electron is
transferred from one atom or molecule to
another
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Electron donor is reducing agent
Electron acceptor is oxidizing agent
The addition of electron to a molecule or atom is
called reduction
Energy is released when electrons are
transferred to lower energy state molecules
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Electron transfer chains
Cellular Respiration Mechanisms
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3 Stages
Glycolysis-happens in cytosol of cell
 Krebs cycle-happens in matrix of mitochondria
 Electron transport and oxidative phophorylation-cristae
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Glycolysis
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Means “sugar splitting”-glucose is split into
Pyruvate
First step of respiration
Broken into two stages
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Energy investment phase-uses 2ATP
Energy Payoff Phase-Yields 4 ATP +2 NADH
Net of 2 ATP
Energy Investment Phase
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Begins with Glucose
2 ATPs are used to phosphorylate Carbons 1
and 6
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Isomerase converts glucose to fructose
structure
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Activated intermediates
Isomerase is enzyme that changes one molecule
to an isomer
Eventually yields 2 molecules of
glyceraldehyde phosphate
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Enters energy payoff phase
Fig. 9-8
Energy investment phase
Glucose
2 ADP + 2 P
2 ATP
used
4 ATP
formed
Energy payoff phase
4 ADP + 4 P
2 NAD+ + 4 e– + 4 H+
2 NADH + 2 H+
2 Pyruvate + 2 H2O
Net
Glucose
4 ATP formed – 2 ATP used
2 NAD+ + 4 e– + 4 H+
2 Pyruvate + 2 H2O
2 ATP
2 NADH + 2 H+
Energy Payoff Phase
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Starts with Glyceraldehyde phosphate
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2 for every glucose
Enzyme adds phosphate GP while 2 NADH
molecules are produces
Phosphates are eventually loss resulting in the
production of 4 ATP molecules
The final product is Pyruvate
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Moves into Krebs cycle
Transition
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Once Pyruvate enters Mitochondrion it is converted to
Acetyl CoA and CO2
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Acetyl CoA is the starting molecule for the Krebs cycle
Fig. 9-10
CYTOSOL
MITOCHONDRION
NAD+
NADH + H+
2
1
Pyruvate
Transport protein
3
CO2
Coenzyme A
Acetyl CoA
Krebs cycle
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Completes the oxidation of organic molecules
Takes place in matrix of mitochondria
Cyclic like Calvin cycle
Produces 1 ATP for each acetyl CoA
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2 per glucose
Many high energy electrons are saved as
3NADH and FADH2 per cycle
Also produces 2 CO2 molecules per cycle
Fig. 9-12-8
Acetyl CoA
CoA—SH
NADH
+H+
H2O
1
NAD+
8
Oxaloacetate
2
Malate
Citrate
Isocitrate
NAD+
Citric
acid
cycle
7
H2O
NADH
+ H+
3
CO2
Fumarate
CoA—SH
6
-Ketoglutarate
4
CoA—SH
5
FADH2
NAD+
FAD
Succinate
GTP GDP
ADP
ATP
Pi
Succinyl
CoA
NADH
+ H+
CO2
Fig. 9-11
Pyruvate
CO2
NAD+
CoA
NADH
+ H+
Acetyl CoA
CoA
CoA
Citric
acid
cycle
FADH2
2 CO2
3 NAD+
3 NADH
FAD
+ 3 H+
ADP + P i
ATP
Transition 2
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NADH and FADH2 are used in the electron
transport chain
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Happens in cristae of mitochondrion
Uses Oxygen as ultimate electron acceptor