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Cellular Pathways that Harvest Chemical Energy : Respiration

Cellular Pathways that Harvest Chemical Energy : Respiration

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Page 1: Cellular Pathways that Harvest Chemical Energy : Respiration

Cellular Pathways that Harvest Chemical Energy : Respiration

Page 2: Cellular Pathways that Harvest Chemical Energy : Respiration

Energy flow and chemical recycling

Page 3: Cellular Pathways that Harvest Chemical Energy : Respiration

Energy For Life

Photosynthesis stores chemical energy into chemical bonds and

Respiration releases the energy stored in the chemical bonds

ATP is the biological currency of Energy

Page 4: Cellular Pathways that Harvest Chemical Energy : Respiration

Oxidation and Reduction

Gain of one or more electrons by an atom, ion or molecule is called Reduction

Oxidation and Reduction always occurs together, one material is oxidized (loss E) and other is Reduced (Gain E)

Page 5: Cellular Pathways that Harvest Chemical Energy : Respiration

Oxidized and Reduced NAD

Coenzyme NAD is a key electron carrier in the redox Rxn

Page 6: Cellular Pathways that Harvest Chemical Energy : Respiration

NAD+ as an electron shuttle

Page 7: Cellular Pathways that Harvest Chemical Energy : Respiration

Energy Carrier

Oxidizing agent (NAD) accepts E in the process of oxidizing the reducing agent (AH2 to A). Oxidizing agent (NAD) becomes reduced (NADH).

Reducing agent donates E and becomes Oxidized as it reduces the Oxidizing agent (B to BH2)

Page 8: Cellular Pathways that Harvest Chemical Energy : Respiration

Cellular Energy

Pathways

Page 9: Cellular Pathways that Harvest Chemical Energy : Respiration

Overview of cellular respiration

Page 10: Cellular Pathways that Harvest Chemical Energy : Respiration

Glycolysis and Fermentation

Page 11: Cellular Pathways that Harvest Chemical Energy : Respiration

Changes in Free EnergyEach step in glycolysis changes the free energy available

Thus after the step 6 each following steps and metabolites or products will have less energy

First you invest energy then harvest it……

Page 12: Cellular Pathways that Harvest Chemical Energy : Respiration

Glycolysis: Glucose to Pyruvate

The energy-investing reactions/phase of Glycolysis

Page 13: Cellular Pathways that Harvest Chemical Energy : Respiration

Glycolysis: Glucose to Pyruvate

Energy-harvesting reactions/phase yields ATP and NADH

Pl note that step 5… each molecule is 2 units because 6C are splits into two 3C molecules

Step 6 to 7 is a substrate-level phosphorylation

Page 14: Cellular Pathways that Harvest Chemical Energy : Respiration

Substrate-level

phosphorylation

Page 15: Cellular Pathways that Harvest Chemical Energy : Respiration

Glu to Pyr

Step 9 to 10 is also a SLP

Glycolysis nets two Molecules of ATP and two Molecules of NADH

4ATP-2ATP=2ATP

In fermentation the net yield is only 2 ATP

Page 16: Cellular Pathways that Harvest Chemical Energy : Respiration

Pyruvate Oxidation (Mito)

PDC is a large complex, Pyruvate DH converts Pyruvate to Acetyl CoA, releasing first Carbon dioxide

Pyruvate is Oxidized to acetyl group, E conserved in NADH and some energy is conserved by comining acetyl group to CoA

Page 17: Cellular Pathways that Harvest Chemical Energy : Respiration

Pyruvate to acetyl CoA

Page 18: Cellular Pathways that Harvest Chemical Energy : Respiration

Citric Acid or TCA Cycle

Acetyl CoA enters the TCA cycle, and CoA regenerated

Page 19: Cellular Pathways that Harvest Chemical Energy : Respiration

TCA Cycle

Page 20: Cellular Pathways that Harvest Chemical Energy : Respiration

Closer look at TCA cycle

Page 21: Cellular Pathways that Harvest Chemical Energy : Respiration

Summary of TCA cycle

Page 22: Cellular Pathways that Harvest Chemical Energy : Respiration

Free EnergyTCA cycle releases more energy than Glycolysis or pyruvate reduction

Page 23: Cellular Pathways that Harvest Chemical Energy : Respiration

Oxidation of NADH + H+

Page 24: Cellular Pathways that Harvest Chemical Energy : Respiration

Resp Chain

Page 25: Cellular Pathways that Harvest Chemical Energy : Respiration

Chemiosmotic Mechanism

Page 26: Cellular Pathways that Harvest Chemical Energy : Respiration

ATP SynthesisATP synthesis is a reversible reaction and ATP synthase can also act as an ATPase hydrolyzing ATP to ADP

Exergoic Rxn from Et drive the Electrogenic pumping of protons out of Mitochondria into IM space

Pot E of proton gradient has two role, act as channel for protons to diffuse back and it uses E of diffusion to make ATP

Page 27: Cellular Pathways that Harvest Chemical Energy : Respiration

Chemi-osmotic

Mechanism

Page 28: Cellular Pathways that Harvest Chemical Energy : Respiration

Chemi-osmotic

MechanismCouples ET to the ATP synthesis using ATP synthase using a Proton Gradient

Page 29: Cellular Pathways that Harvest Chemical Energy : Respiration

Lactic Acid Fermentation

Page 30: Cellular Pathways that Harvest Chemical Energy : Respiration

Alcoholic Fermentation

Page 31: Cellular Pathways that Harvest Chemical Energy : Respiration

Cellular Respiration

Theoretical Net ATP yield from the complete oxidation each glucose molecule is 36 ATP, but never in a living system

Page 32: Cellular Pathways that Harvest Chemical Energy : Respiration

Cellular Respiration

Page 33: Cellular Pathways that Harvest Chemical Energy : Respiration

Cellular Respiration

Page 34: Cellular Pathways that Harvest Chemical Energy : Respiration

ATP molecules during cellular respiration

Page 35: Cellular Pathways that Harvest Chemical Energy : Respiration

Relationship among the other major Metabolic Pathways

Page 36: Cellular Pathways that Harvest Chemical Energy : Respiration

Catabolism of various food molecules

Page 37: Cellular Pathways that Harvest Chemical Energy : Respiration

Coupling Metabolic Pathways

OAA and Asp interconverts, is called Transamination

Page 38: Cellular Pathways that Harvest Chemical Energy : Respiration

Regul by Negative

and Positive

FeedbackExcess accumulation of some products can shut down their synthesis or stimulate synthesis of other products

Page 39: Cellular Pathways that Harvest Chemical Energy : Respiration

Feedback Regulation

Citrate and ATP inhibits PFK thus Glycolysis

ADP and AMP stimulates Glycolysis

Page 40: Cellular Pathways that Harvest Chemical Energy : Respiration

Feedback Regulation

ATP and NADH inhibits TCA cycle

Citrate stimulates FA-CoA Rxn

NAD and ADP activated ICDH

ATP and NADH inhibits KGADH

Page 41: Cellular Pathways that Harvest Chemical Energy : Respiration

Control of cellular respiration

Page 42: Cellular Pathways that Harvest Chemical Energy : Respiration

Energy flow and chemical recycling

Page 43: Cellular Pathways that Harvest Chemical Energy : Respiration

SummaryPhotosynthesis places energy into chemical bonds and respiration releases it

Glycolysis, TCA cycle,and ET chain and ATP synthesis

Fermentation of pyruvate to lactate or ethanol

Oxidation reduction reactions

Chemiosmotic synthesis of ATP using a proton gradient

Regulation of Metabolic pathways by positive and negative feedback

Various metabolic pathways inter-communicate with each other

Pl read pages 134-135 for a detailed summary