Housekeeping

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Housekeeping

• Exams back Thursday
• after fall break
• Lab reports
• after fall break in lab
• Bioterrorism reports (the 29th)
• Printout of references
• Metastasis reading (read by next Thursday)
• NO LAB NEXT WEEK!
• Class on Thursday (the 24th)

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Cell has work to do
Cellular respiration
Fermentation
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The Basics of Catabolism
Reactants
Products
Transfer of electrons
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Redox reactions
Transfer of electrons

• Oxidation loss of electrons
• Reduction gain of electrons

Reducing agent
Xe- Y
X Ye-
Oxidizing agent
Transfer of electrons creates energy!
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KEY Electrons move from low to high
electronegativity
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Cellular respiration
REACTANTS
PRODUCTS
Carbon water dioxide
Glucose oxygen
C6H12O6
6 CO2

6 O2

6 H2O
Reduction
Oxidation
Is oxygen an oxidizing agent or a reducing agent?
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Why is oxygen such a great oxidizing agent?
Electronegativity!
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Redox reactions
Transfer of electrons
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What do we need?

• Transfer of energy
• Electron acceptors (oxygen)
• Enzymes

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Steps of Catabolism
Transfer energy with transfer of electrons
MULTIPLE STEPS!
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Harvest energy

• Steps!

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Glucose (food)
Low electronegativity
Energy
NADH
Electron transport chain
Oxygen
High electronegativity
ATP
Phosphorylation
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NAD
Can accept 2 e-s
Picks up 2 e-s and 1 proton
WHY NAD??
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Cellular respiration

• Glycolysis
• Glucose ? 2 pyruvate
• Redox reactions release NADH
• Cytosol
• Kreb cycle
• Pyruvate ? CO2
• Redox reactions release NADH
• Mitochondrial matrix
• Electron transport chain
• Accepts electrons (from NADH)
• Make ATP
• Inner membrane of the mitochondria

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Transfers e-s to Oxygen
Phosphate group transferred to ADP from a
substrate
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Substrate-level phosphorylation Oxidative
phosphorylation
38 ATP
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Glycolysis

• Glucose ? 2 pyruvate 2ATP 2NADH
• Dont lose any carbon
• 6-C glucose ? 2 3-C pyruvate

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Glycolysis

• 10 steps
• 5 need energy
• 5 release energy

• No oxygen necessary

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A lot of ENERGY still in pyruvate!
Kreb cycle
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• Pyruvate ? acetyl CoA
• CO2 released
• Acetate formed (NAD ? NADH)
• Coenzyme A attached
• Broken into eight steps

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Krebs cycle
Acetyl-CoA (2 Carbons)
2 CO2 3NADH 1 FADH 1 ATP
Actually 2 Acetyl-CoAs from glycolysis!!
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In sum
Glycolysis (2 ATP 2 NADH)

Acetyl CoA synthesis (2 NADH)

Krebs cycle (1 ATP 3 NADH 1 FADH)

Krebs cycle (1 ATP 3 NADH 1 FADH)
4 ATP 10 NADH 2 FADH
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4 ATP 10 NADH 2 FADH
Most of the energy is stored in NADH and FADH
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Electron transport

• Mitochondria inner membrane
• Series of molecules
• Mostly proteins
• Prosthetic groups
• Series of redox reactions
• Transfer of electrons

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Cytochromes protein heme group
Flavomononucleotide
2 NADH ? 2 H2O ATP isnt made directly
Ubiquinone (lipid)
Oxygen
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ATP synthase
PROTON MOTIVE FORCE
How is the electrochemical gradient created?
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ENERGY COUPLING Chemiosmosis
Exergonic reaction releases energy
Endergonic reaction Uses the released energy
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Chemiosmosis
NADH ? 3 ATPS
FADH ? 2 ATPS
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In sum
Glycolysis (2 ATP 2 NADH)

Acetyl CoA synthesis (2 NADH)

Krebs cycle (1 ATP 3 NADH 1 FADH)

Krebs cycle (1 ATP 3 NADH 1 FADH)
4 ATP 10 NADH 2 FADH
How many ATP??
38 ATP
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REACTANTS
PRODUCTS
C6H12O6 6 O2
6 CO2 6 H2O
Glucose oxygen
Carbon water dioxide
? G -686 kcal/mol
REACTANTS
PRODUCTS
ATP H2O
ADP P ENERGY
? G 13 kcal/mol
38 ATP ? 13 494 kcal/mol
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Some animals live without oxygenHow do they
harvest energy?
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Fermentation

• Aerobic with oxygen
• glycolysis ? ETC
• Anaerobic without oxygen
• glycolysis
• recycle of NAD

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Alcohol fermentation
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Lactic acid fermentation
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Aerobic
Anaerobic

• Glycolysis ? pyruvate
• 2 ATP made
• NAD is oxidizing agent (accepts e-s)
• Oxygen is the final e- acceptor to regenerate
  NAD from NADH and ATP IS MADE

• Glycolysis ? pyruvate
• 2 ATP made
• NAD is oxidizing agent (accepts e-s)
• Organic molecule is the final e-acceptor to
  regenerate NAD from NADH

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Cell has work to do
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How is Cellular Respiration regulated?
Feedback Inhibition
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We need to interact with the environment-get our
food for energy
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Food
Autotrophs
Inorganics (CO2)
Producers
Organic compounds
Heterotrophs
Consumers
Animals, fungi, most bacteria
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What do plants need?

• CO2
• H2O
• Minerals (soil)
• Light (energy)

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A new type of bacterium was identified as a
photoautotroph. What food does it require for
survival? Where do heterotrophs get their food?
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Photosynthesis
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Is photosynthesis a redox reaction? What are its
reducing and oxidizing agents?
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Photosynthesis a redox reaction
Light
Energy
6CO2
C6H12O6

6O2

6H2O

Oxidation
Reduction
REVERSAL OF CELLULAR RESPIRATION!
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Photosynthesis
Energy
C6H12O6 6O2
6CO2 6H2O Light
Cellular Respiration
Energy
C6H12O6 6O2
6CO2 6H2O
Both Redox reactions! Opposite reaction!
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Light reaction

• Light Energy ? Chemical energy
• Transfer of electrons to NADP
• O2 released
• 1 ATP made

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Calvin cycle (Dark reactions)

• Carbon fixation (CO2 ? sugar)
• Carbon fixation and reduction (CO2 ? sugar)
• Needs NADPH and ATP for energy

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Photosynthesis
Light cycle
Light
Energy
6CO2
C6H12O6

6O2

6H2O

Calvin cycle