Download Recitation Presentation #7 - McKenna`s MBios 303 Archive Site

5/29/2008
May 29th, 2008
Biochemistry Recitation
MBioS 303
Summer 2008
Outline
Oxidation and Reduction
Glycolysis
Aerobic vs. anaerobic metabolism
TCA Cycle
Oxidative Phosphorylation
Q Cycle
ATP Synthase
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Oxidation and Reduction
What are Oxidation and Reduction?
Oxidation: Loss of electrons
Reduction: Gain of electrons
Redox reactions are always paired!
Aox
Box
Ared
Bred
Aox + Bred Ared + Box
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Is it Oxidation or Reduction?
How can you tell if an organic molecule has been oxidized or
reduced?
If it gains oxygen/loses hydrogen it has been oxidized!
If it loses oxygen/gains hydrogen it has been reduced!
At each step shown below, has the molecule been oxidized or
reduced?
2 e- + 2 H+
H2O
Examples
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NAD+
NADH
2
NAD+
NADH
3
NADH
NAD+
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Reduction Potential
The tendency of a species to acquire electrons, becoming
reduced.
A more positive number = a higher reduction potential
A more negative number = a lower reduction potential
EX. Fe-S Clusters in Complex I of the ETC
N1-a: -0.380 V
e- transfer
N-4: -0.250 V
e- transfer
N-2: -0.100 V
Glycolysis
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Where Does Glycolysis Occur?
http://kentsimmons.uwinnipeg.ca/cm1504/Image152.gif
Where Does Glycolysis Occur?
http://nobelprize.org/nobel_prizes/medicine/laureates/1999/illpres/
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Glycolysis (glyco = sugar; lysis = breaking)
OVERALL REACTION:
Glucose + 2 NAD+ + 2 Pi + 2 ADP 2 pyruvate + 2 NADH
+ 2 ATP + 2 H2O
Preparatory Phase: must input two ATP molecules
Payoff Phase: generate 4 ATP molecules, 2 NADH
Glycolysis: Preparatory Phase
ΔG = -33.4 kJ/mol
ΔG = -22.2 kJ/mol
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Glycolysis: Payoff Phase
ΔG = -16.7 kJ/mol
Fates of Pyruvate
Acetyl-CoA to Citric Acid Cycle (aerobic conditions)
Ethanol or Lactate (anaerobic conditions)
NO ATP IS MADE – WHY DO THIS?
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Glycolysis: Payoff Phase
TCA Cycle
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Where Does the TCA Cycle Occur?
http://kentsimmons.uwinnipeg.ca/cm1504/Image152.gif
Where Does the TCA Cycle Occur?
Molecular Cell Biology, 4 th Ed.
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The TCA Cycle
Located in inner
mitochondrial
membrane
Succinate Dehydrogenase
http://en.wikipedia.org/wiki/Image:SuccDeh.svg
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Oxidative Phosphorylation
Where Does OxPhos Occur?
http://kentsimmons.uwinnipeg.ca/cm1504/Image152.gif
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Where Does OxPhos Occur?
http://en.wikipedia.org/wiki/Image:Mitochondrial_electron_transport_chain%E2%80%94Etc4.svg
Why Do Oxidative Phosphorylation?
What is the goal of this metabolic process?
Use energy stored in reduced electron carriers to make ATP!
Harness energy in electron carriers to generate a proton gradient
Energy in proton gradient used to make ATP
http://en.wikipedia.org/wiki/Image:ETC.PNG
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The Q Cycle
2 Step Process
Needed to convert between 2 electron carrier (Coenzyme Q)
and 1 electron carrier (Cytochrome c)
Biochemistry, 5 th Ed.
The Q Cycle
http://en.wikipedia.org/wiki/Image:Complex_III.png
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Electron Flow Through ETC
Molecular Cell Biology, 4th Ed.
ATP Synthase
http://www.dnatube.com/view_video2.php?viewkey=404a45ecacaaf05e5f73
http://www.biologie.uni-osnabrueck.de/Biophysik/Bilder_und_Filme/MOV/ATPase-e-RV-low.mov
http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/f1fo.htm
http://www.bio.davidson.edu/Courses/Molbio/MolStudents/spring2005/Carlson/ATP%20Synthase1.html
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Total ATP Generation
QUIZ TIME!
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