1 1 11/3/2015 cellular respiration filename: respire.ppt
TRANSCRIPT
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Cellular Respiration
Filename: Respire.ppt
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Lecture Outline
• Using Chemical energy to drive metabolism• Production of ATP• Cellular respiration
– Clycolysis– Krebs cycle– Electron transport – Chemiosmosis
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Lecture Overview
• All organisms drive their metabolism with ATP generated from
• Rearrangement of chemical bonds • Energetic electrons from proton pumps• Electrons from photosynthesis • Electrons from oxidation of sugars and fats
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Background Terms & Concepts
• Glucose• Chemiosmosis• Oxidation- reduction• ATP• Exergonic vs endergonic reactions
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Concepts from OAC
• Synthesis of ATP• Glycolysis: Krebs cycle• anaerobic vs aerobic glucose catabolism• Energy from fats & proteins
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Energy Flow & Recyling
Energy Poor
Energy Rich
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Cellular Respiration
• Release of energy stored in organic compounds
– Carbohydrate– Fats– Proteins (net energy loss)
• Oxygen is consumed as a reactant• Carbon dioxide and water are byproducts• Energy is used indirectly
– trapped as ATP
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Pathways in Cellular Respiration
• Glycolysis• Krebs cycle• Electron transport chain
Cellular RespirationCumulative function of three
metabolic pathways and chemiosmosis
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Catabolism of various foods
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Overview of Cellular RespirationA room of your own...
ATP ATPATP
Glycolysis occurs whether or not oxygen is
present
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Glycolysis
• OCCURS in the CYTOPLASM• Glucose (6 carbon sugar) >>>
2 pyruvate (3 carbon sugar)• Energy investment phase• Energy yielding phase• Net yield of energy
No Carbon dioxide is released No Carbon dioxide is released during glycolysisduring glycolysis
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Electron Transport
System
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Glycolysis
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Glycolysis: Energy Investment
• Glucose + ATP-> glucose-6-P + ADP– hexokinase
• Glucose-6-P -> Fructose-6-P– phosphoglucoisomerase
• Fructose-6-P + ATP -> Fructose 1,6, diphosphate + ADP– phosophofructokinase
• Fructose 1,6,diphosphate -> glyceraldehyde phosphate + dihydroxyacetone phosphate– aldolase
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Energy Investment Phase
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More ATP investment
ATP Investment
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Isomerization
• glyceraldehyde phosphate & dihydroxyacetone phosphate are isomers– Isomerase interconverts– glyceraldehyde phosphate removed next as
next step
• THUS Equilibrium between the two sugars is in direction of glyceraldehyde phosphate
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Glycolysis: Energy Yield Phase
• Glyceraldehyde-P + 2NAD+ +2Pi ->
1,3 glycerophosphate + 2 NADH + 2 H+• !,3 glycerophosphate + 2ADP -> 3 phosphoglycerate + 2 ATP• Relocate phosphate group• Remove water to create phosphoenolpyruvate• Remove phosphate from PEP• PEP + 2ADP -> pyruvate + 2ATP
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The first payoff (substrate-level phosphorylation)
Substrate level Phosphorylation
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More dividends (substrate-level phosphorylation)
More Energy Payoff
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Glycolysis: Net Energy Yield
• Glucose >>> 2 pyruvate• 2 ADP >>> 2 ATP• 2 NAD+ >>> 2NADH
NADH>>> electron transport chain NADH>>> electron transport chain if oxygen is presentif oxygen is present
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Alternate Glycolytic Pathway• Glycolysis• Embden-Meyerhof• Glucose>> glucose-6
phosphate• Fructose-6 phosphate• Fructose 1,6 diphosphate• ISOMERS
– dihydroxyacetone phosphate
– Glyceraldehyde 3 P
• Alternate• Enter-Doudoroff• Glucose>> glucose-6
phosphate• 6 phosphogluconic acid• Keto deoxy 6 phoshogluconic
acid• pyruvic acid + Glyceraldehyde
3 P
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Pyruvate
Fermentation
Oxidativephosphorylation
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Role of Pyruvate
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Formation of Acetyl CoA
• Pyruvate translocated from cytoplasm to mitochrondial matrix
• Pyruvate + NAD+ -> Acetate + NADH + CO2
• Acetyl group attached to Coenzyme A
Acetyl CoA links glycolysis to the Krebs cycle
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Formation of Acetyl CoA
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Krebs cycle• oxidation of pyruvate generated by glycolysis
– glucose->2 pyruvate• Generates 1 molecule of ATP/ pyruvate
– substrate level phosphorylation• Generates 4 molecules of NADH / pyruvate• Generates 1 molecule of FADH2/ pyruvate • Generate 3 molecules of carbon dioxide
• OCCURS in MITOCHONDRIAL MATRIX• occurs in prokaryotic cytoplasm
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Krebs cycle
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Summary of Krebs Cycle
IN
IN
IN
IN
Out
Out
Out
Out
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Krebs Cycle Balance Sheet
• Input• Water• ADP• NAD+• FAD+• Acetyl CoA
• Output• Carbon Dioxide• ATP• NADH• FADH