PowerPoint 4 - Microbial Metabolism
Page 1: Introduction
College Physics Chapter: Microbial Metabolism
Presentation modified for BIO 275 (CVCC)
Licensed under Creative Commons
Access resources: OpenStax Microbiology
Page 2: Metabolic Diversity of Prokaryotes
Prokaryotes display significant metabolic diversity which impacts life forms.
Acidic Mine Drainage:
Result of mining processes introducing oxygen and water to sulfide-oxidizing bacteria.
Leads to sulfuric acid production, harming aquatic life.
Nitrogen-Fixing Bacteria:
Found in root nodules of plants, converting atmospheric nitrogen into ammonia.
Provides usable nitrogen for plants.
Page 3: Understanding Metabolism
Metabolism: Collection of biochemical reactions in living organisms.
Anabolic Reactions: Require energy to construct larger molecules (endergonic).
Catabolic Reactions: Release energy by breaking down larger molecules (exergonic).
Both pathways are essential for energy balance within cells.
Page 4: Classification of Organisms by Energy Source
Organisms categorized by energy acquisition:
Autotrophs (Producers):
Convert inorganic CO2 into organic compounds (carbohydrates, lipids).
Examples: Plants, algae, cyanobacteria (photoautotrophs).
Heterotrophs (Consumers):
Depend on organic compounds for nutrients (animals, fungi, protozoans).
Decomposers: A type of heterotroph.
Page 5: Sources of Energy in Organisms
Electrons as Energy Carriers:
Energy derived from electron transfer; sources vary among organisms.
Phototrophs: Obtain energy from light.
Chemotrophs: Gain energy from breaking chemical bonds, often in organic compounds.
Page 6: Classifying Chemotrophs
Chemotrophs divided into two groups:
Organotrophs: Derive energy from organic compounds (e.g., humans, fungi).
Lithotrophs: Obtain energy from inorganic compounds (e.g., some prokaryotes).
Page 7: Energy Source Classification
Chemoheterotrophs:
Use organic molecules for both electron and carbon sources.
Energy Source / Carbon Source:
Chemotrophs:
Chemoautotrophs (Chemical, Inorganic) - various bacteria.
Chemoheterotrophs (Chemical, Organic) - animals, most fungi, most bacteria.
Phototrophs:
Photoautotrophs (Light, Inorganic) - plants, algae.
Photoheterotrophs (Light, Organic) - certain bacteria.
Page 8: Oxidation-Reduction Reactions
Electron Transfer:
Oxidation: Molecules lose electrons (oxidized).
Reduction: Molecules gain electrons (reduced).
Allows for energy transfer in smaller packets, preventing energy bursts in cells.
Page 9: Redox Reactions Summary
Mnemonic to remember: LEO GER.
Lose Electrons = Oxidized; Gain Electrons = Reduced.
Oxidation and reduction occur simultaneously (redox reactions).
Page 10: Mechanisms of Oxidation-Reduction
Molecule can be oxidized by:
Losing an electron, losing a hydrogen atom, or gaining an oxygen atom.
Molecule can be reduced by:
Gaining an electron or gaining a hydrogen atom.
Dehydrogenation Reactions: Loss of hydrogen atoms in oxidation.[
Page 13: Adenosine Triphosphate (ATP) Structure
ATP Composition:
Nitrogenous adenine base, ribose sugar, three phosphate groups (high-energy bonds).
ATP functions as the primary energy currency of the cell.
Page 16: ATP in Cellular Work
Cellular Functions:
Energy from ATP hydrolysis drives metabolic work including anabolic pathways.
ATP is regenerated through phosphorylation using chemical or sunlight energy.
Page 17: Coupled Reactions in Metabolism
Coupled Exergonic and Endergonic Reactions:
Endergonic ATP phosphorylation is coupled with exergonic catabolism.
Helps conserve energy through recycling.
Page 18: Role of Enzymes in Reactions
Enzymes as Catalysts:
Enzymes lower activation energy for reactions, necessary for spontaneous occurrence.
Enzymatic activity speeds up both endergonic and exergonic reactions.
Page 19: Impact of Enzymes on Activation Energy
Illustration of Activation Energy:
Enzymes facilitate lowering activation energy for both reaction types.
Critical for efficient metabolic processes.
Page 20: Enzyme Structure and Specificity
Nature of Enzymes:
Usually protein molecules with specific 3D shapes for substrate binding.
Substrates bind at the active site to form an enzyme-substrate complex.
Page 21: Induced-Fit Model in Enzyme Function
Complex Formation:
Substrates bind to the active site, forming temporary complexes.
Induced-fit model suggests substrate stretching to weaken bonds, speeding reactions.
Page 22: Induced Fit Mechanism
Active site undergoes conformational change upon substrate binding, enhancing reaction speed.
Page 23: Naming Enzymes
Common Naming Convention:
Enzymes typically end in “-ase” and are often named based on substrates or actions.
Examples: Ligase, Transferase, Lipase, Dehydrogenase.
Page 24: Factors Affecting Enzyme Activity
Denaturation Impacts:
Temperature changes, pH shifts, and exposure to chemicals can affect activity.
Each enzyme has an optimal range for effectiveness.
Page 25: Enzymatic Function and Helper Molecules
Helper Molecules:
Some enzymes require non-protein helpers (cofactors/coenzymes) for functionality.
These can alter the active site shape for better substrate affinity.
Page 26: Cofactors and Coenzymes
Types:
Cofactors: Inorganic ions (e.g., Fe²⁺, Mg²⁺).
Coenzymes: Organic molecules (e.g., vitamins) that assist enzymes.
Page 27: Holoenzymes and Apoenzymes
Enzyme Activation:
Binding of coenzymes or cofactors forms active holoenzyme from inactive apoenzyme.
Page 28: Enzyme Regulation Mechanisms
Competitive Inhibitors:
Compete with substrates at the active site, blocking binding.
Reversible inhibitors can be overcome by increasing substrate concentration.
Example: Sulfa drugs inhibit bacterial folic acid biosynthesis.
Page 29: Non-Competitive Inhibition**
Allosteric Inhibitors: bind to different sites, altering enzyme shape and reducing substrate affinity.
Activators: enhance substrate binding at allosteric sites.
Page 30: Summary of Enzyme Activity Regulation
Enzymes regulated by either competitive (active site) or noncompetitive (allosteric site) inhibitors.
Page 31: Metabolic Pathways Overview
Sequential Reactions:
Each reaction requires a specific enzyme; if any are missing, the pathway halts.
Metabolic pathways consist of sequential catalyzed reactions.
Page 32: Feedback Inhibition in Metabolic Pathways
Product Regulation:
The endpoint product can act as an inhibitor in early pathway steps, preventing resource wastage.
Page 33: Allosteric Mechanisms in Feedback Inhibition
Binding of inhibitors or activators to allosteric sites affects enzymatic activity in feedback mechanisms.
Page 34: Glycolysis Overview
Universal Process:
Nearly all organisms undergo glycolysis in either prokaryotic or eukaryotic cells.
Conversion of glucose into pyruvate with some ATP produced.
Page 35: Phases of Glycolysis
Energy Investment Phase:
2 ATP used to convert glucose into two phosphorylated G3P molecules.
Energy Payoff Phase: Extracts energy by oxidizing G3P to pyruvate, yielding ATP and NADH.
Page 36: Glycolysis Pathway Summary
Investment phase yields two G3P and payoff phase results in four ATP and two NADH.
Net gain of 2 ATP from glycolysis.
Page 37: Energy Investment Pathway Details
Begins with glucose, ends with two G3P, requires 2 ATP input.
Page 38: Energy Payoff Pathway Overview
Follows energy investment, produces NADH and ATP, ending in pyruvate.
Page 39: Substrate-Level Phosphorylation
ATP formation occurs through substrate-level phosphorylation during glycolysis.
Page 40: Glycolysis Summary
Key outcomes of glycolysis summarized, detailing net products produced.
Page 41: Alternative Glycolytic Pathway: ED Pathway
Entner-Doudoroff (ED) Pathway:
Used by some prokaryotes like Pseudomonas aeruginosa, producing less ATP than EMP pathway.
Page 45: Krebs Cycle Initiation
Acetyl-CoA enters the Krebs cycle (TCA), occurring in cytoplasm (prokaryotes) or mitochondria (eukaryotes).
Page 46: Purpose of the Krebs Cycle
Continue capturing energy from glucose breakdown via redox reactions producing NADH and FADH2.
Page 47: Krebs Cycle Outputs
Each complete cycle yields products including CO2, ATP/GTP, NADH, FADH2 and plays a role in biosynthesis.
Page 48: Overview of the Krebs Cycle
Detailed outputs per turn, highlighting significance for energy storage.
Page 50: ATP Production via Oxidative Phosphorylation
Final electron acceptors in the process lead to substantial ATP generation through electron transport system.
Page 51: Electron Transport System Function
A series of reactions transferring electrons through membrane-bound carriers, pumping protons across membranes.
Page 53: Proton Storage During Electron Transport
Proton gradients form across membranes during electron transfer, crucial for ATP synthesis.
Page 55: Establishing Proton Gradients
Accumulation of protons on one side of the membrane creates an electrochemical gradient.
Page 57: Mechanism of ATP Synthase
ATP synthase utilizes proton gradients to synthesize ATP utilizing chemiosmosis.
Page 59: ATP Synthase Structure
Overview of ATP synthase as integrated into prokaryotic membranes and its mechanism of action.
Page 60: Bacterial Electron Transport Chain Overview
Describes how H+ ions are pumped and their role in ATP generation through oxidative phosphorylation.
Page 61: ATP Yield Variability
Theoretical maximum ATP yield in aerobic respiration; actual yield varies by species.
Page 63: Limitations to Aerobic Respiration
Factors limiting respiration include absence of final electron acceptors and genetic constraints on enzyme production.
Page 64: Purpose of Fermentation
Fermentation regenerates NAD+ necessary for glycolysis amid low oxygen availability.
Page 65: Human Applications of Fermentation
Used in food production and diagnostics, with implications for health and industry.
Page 66: Lactic Acid Fermentation Process
Lactic acid produced in human muscles under oxygen depletion and in fermentation processes.
Page 68: Human Role of Lactic Acid Bacteria
Importance of lactic acid bacteria in human microbiota for digestion and health.
Page 69: Alcohol Fermentation Overview
Chemical reactions involved in ethanol production noted for food and beverage industries.
Page 70: Common Fermentation Pathways
Summary of various fermentation pathways and associated products with microbial examples.
Page 71: Analytical Profile Index Test Utilization
Use of API strips for identification of bacterial species based on metabolic product tests.
Page 72: Photosynthesis Phases
Overview of the photosynthesis process: light-dependent vs. light-independent reactions.
Page 73: Photosynthesis Summary
Captures light energy conversion into chemical energy during the initial phases.
Page 76: Photosynthetic Pigments
Various pigments involved in light absorption during photosynthesis and their significance.
Page 79: Noncyclic Photophosphorylation
Describes electron flow paths and processes involved in ATP and NADPH production in plants.
Page 80: Electron Replacement During Photosynthesis
Water as the electron donor in oxygenic photosynthesis; alternatives in anaerobic bacteria.
Page 81: Types of Photosystems
Difference between photosystem types: PSI and PSII with their respective functions outlined.
Page 83: Calvin Cycle Overview
Calvin cycle’s role in fixing carbon into stable forms using ATP and NADPH.
Page 84: Carbon Fixation Steps
Detailed functions of rubisco during carbon fixation and subsequent ATP/NADPH consumption.
Page 90: Nitrogen Cycle Processes
Explanation of ammonification, nitrification, and their significance in soil health.
Page 91: Denitrification Process Overview
Nitrate reduction done by soil bacteria, emphasizing the environmental implications.
Page 92: Sulfur Cycle Summary
Overview of sulfur cycling, illustrating its importance for organisms.