Respiration
Page 1: Overview of Aerobic Respiration and Metabolic Pathways
Key Components in Energy Production
Citrate: Important in the citric acid cycle; it transfers energy through intermediates (e.g., via Acetyl CoA).
Acetyl CoA: A central molecule in metabolism that transitions pyruvate into the citric acid cycle.
NADH & FADH: Electron carriers that transport electrons to the electron transport chain.
Inhibition and Stimulation Factors
Inhibited by ATP and high energy molecules (e.g., succinyl CoA).
Stimulated by ADP and CO2, indicating energy needs.
Page 2: Learning Goals
Regions of Mitochondria: Identify and describe functions.
Conversion of Pyruvate to Acetyl CoA: Understand location and components of pyruvate dehydrogenase complex.
Aerobic Respiration Summary: Summarize key reactions.
Control of the Citric Acid Cycle: Mechanisms of regulation.
Oxidative Phosphorylation: Explain importance and mechanism.
Amino Acids in Citric Acid Cycle: Conversion processes.
Urea Cycle: Importance and steps.
Hyperammonemia: Causes, effects, and significance.
Role of the Citric Acid Cycle: Overview in catabolism and anabolism.
Page 3: Overview of Catabolic Processes
Nutrients (carbohydrates, fats, proteins) release energy through catabolism.
Carbohydrates are a primary energy source.
Page 4: Structure of Mitochondria
Mitochondria: Dual membrane, highly folded structure (cristae).
Membrane Parts:
Outer membrane: More permeable.
Inner membrane: Houses ATP synthase and electron transport system.
Matrix: Site for citric acid cycle, beta-oxidation, and amino acid degradation.
Page 5: Pyruvate to Acetyl CoA Conversion
Under aerobic conditions, pyruvate is converted to acetyl CoA in mitochondria.
Conversion activates acetyl for the citric acid cycle (Krebs cycle).
Page 6: Acetyl CoA Formation
Pyruvate enters the mitochondria; undergoes conversion to a 2-carbon acetyl group.
Activation through bonding with coenzyme A via high-energy thioester bond.
Page 7: Decarboxylation and Oxidation of Pyruvate
Steps:
Decarboxylation (loss of CO2).
Oxidation using NAD, producing NADH.
Acetyl group linked to coenzyme A.
Involves 3 enzymes and 5 coenzymes bundled in the pyruvate dehydrogenase complex.
Page 8: Detailed Decarboxylation & Oxidation
Same steps as Page 7 emphasized: loss of carboxyl group, oxidation, and thioester bond formation.
Page 9: Pyruvate Dehydrogenase Complex
Comprising 5 coenzymes (4 vitamin-derived) and 3 enzymes:
Thiamine pyrophosphate (from thiamine).
FAD (from riboflavin).
NAD (from niacin).
Coenzyme A (from pantothenic acid).
Lipoamide.
Page 10: Role of Acetyl CoA in Metabolism
Central in metabolism, transporting acetyl group to the citric acid cycle.
Also functions in biosynthetic reactions for cholesterol and fatty acid production.
Interconversion of energy from fats, proteins, and carbohydrates.
Page 11: Overview of Aerobic Respiration
Breakdown of food with oxygen, producing ATP, via oxidative phosphorylation.
Performed in the mitochondrial matrix.
Involves oxidations transferring hydride to NAD or FAD, with electron transport to O2.
Page 12: The Citric Acid Cycle
Final stage of nutrient breakdown.
Acetyl CoA and oxaloacetate initiate the cycle.
Acetyl oxidized to CO2 and electrons transferred to NAD and FAD.
Involves 8 enzymatic steps with allosteric control.
Page 13: Details of the Citric Acid Cycle
Emphasizes dietary nutrient breakdown and energy production: Acetyl CoA + oxaloacetate generating NADH and FADH2.
Page 14: Control of the Citric Acid Cycle
Responds to energy needs; accelerates when ATP demand increases.
Four key enzymes regulated allosterically.
Page 15: Allosterically Regulated Reactions
Key steps:
Pyruvate to Acetyl CoA influenced by ATP/NADH levels.
Synthesis of citrate is negatively affected by ATP.
Isocitrate to α-ketoglutarate regulated by ADP and inhibited by NADH/ATP levels.
α-Ketoglutarate to succinyl CoA influenced by ATP/Succinyl CoA/NADH.
Page 16: Oxidative Phosphorylation
Respiratory electron transport system consists of electron carriers in the inner mitochondrial membrane.
NADH yields 3 ATP; FADH2 yields 2 ATP.
ATP synthesis via ATP synthase (F0F1 complex).
Page 17: Energy Yield from Glucose
Summary of ATP yield from glycolysis, pyruvate conversion, and citric acid cycle.
Total net ATP: 36.
Page 18: Electron Transport Systems
Carbohydrates, fats, proteins release energy, primarily using carbohydrates.
Page 19: Electron Transport Systems Overview
Components include coenzymes and cytochromes in the mitochondrial membrane, organized for electron transfers.
Page 20: The Hydrogen Ion Gradient
Protons pumped from matrix to intermembrane space contribute to a high-energy H+ reservoir, facilitating ATP production.
NADH dehydrogenase transfers electrons across all 3 sites; FADH2 oxidation across 2 sites.
Page 21: Electron Flow Through Electron Carriers
Flow of electrons in the electron transport system, leading to ATP synthesis.
Page 22: NADH and ATP Production
NADH transports electrons into the electron transport system, generating ATP through proton pumps.
Page 23: ATP Synthase Function
Protons flow through ATP synthase's F0 channel to catalyze ATP phosphorylation from ADP.
Page 24: Amino Acid Catabolism
Catabolism of proteins for energy, with carbohydrates as primary fuels.
Page 25: Degradation of Amino Acids
In starvation, amino acids are degraded for energy in the liver through transamination and carbon skeleton degradation.
Page 26: Transamination Process
Transfer of α-amino group by transaminase, often involving α-ketoglutarate.
Page 27: Pyridoxal Phosphate
Coenzyme for transamination, derived from vitamin B6 (pyridoxine).
Page 28: Aspartate Transaminase
Catalyzes aspartate's α-amino group transfer to produce oxaloacetate and glutamate.
Page 29: Alanine Transaminase
Transfers alanine's α-amino group to α-ketoglutarate, producing pyruvate and glutamate.
Page 30: Oxidative Deamination
Breakdown of glutamate through glutamate dehydrogenase, liberating ammonium ion.
Page 31: Deamination of an α-Amino Acid
Conversion process involving ammonium ions and Urea Cycle participation.
Page 32: Amino Acid Metabolism Diagram
Various amino acids degrade into key metabolic intermediates like Acetyl CoA and others.
Page 33: The Urea Cycle
Critical for removing toxic ammonium ions produced during amino acid breakdown.
Urea is formed and excreted; enzyme deficiencies can lead to hyperammonemia.
Page 34: Urea Cycle Pathway
Diagram illustrating key components and steps in urea cycle mechanics.
Page 35: Ammonia Toxicity
High ammonia levels are toxic; converted to urea for safe excretion through kidneys.
Page 36: Dual Function of the Citric Acid Cycle
Functions in both catabolism and anabolism; intermediates can be transformed into amino acids.
Page 37: Pathways for Biosynthetic Precursors
Citric acid cycle provides intermediates for synthesizing various molecules like glucose, nucleotides, and lipids.
Page 38: Overview of Amino Acid and Fatty Acid Metabolism
Integration of metabolic pathways for amino acids, fatty acids, and carbohydrates, showing interconnected biosynthetic pathways.