L9- BIOENERGETICS
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CAK!! STUDY KE TUEEE.. GOODLUCKK!! SAYA TEMAN SKALI TAU HEHE
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Course Information
Module: MBBS 240 (General Module Year 1) 2023/2024
Topic: Bioenergetics & Overview of Intermediary Metabolism
Instructor: Sharaniza Ab. Rahim (PhD.)
Affiliation: Biochemistry & Molecular Medicine, Faculty of Medicine, UiTM
Date: 24 October 2023
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Specific Learning Objectives
Define the term "bioenergetics".
Differentiate between exergonic and endergonic reactions.
Differentiate between intermediary metabolism, anabolism, and catabolism.
List high energy molecules in the cells and explain their role in metabolism:
ATP
NAD
NADH
FAD
FADH2
NADPH
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Four Essential Needs for Cells
Molecular building blocks (e.g., amino acids, nucleotides, lipids)
Chemical catalysts (e.g., enzymes)
Information to guide activities (DNA, RNA)
Energy to drive various reactions and processes
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Energy:
Capacity to do work, to move matter against opposing forces.
Capacity to cause specific physical or chemical changes.
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Biological Work
Cells need energy for:
Synthetic Work: changes in chemical bonds
Mechanical Work: changes in location or orientation
Concentration Work: moving molecules across membranes
Electrical Work: moving ions across membranes
Heat and Light Generation: increasing temperature for adaptation or production of light
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Metabolism:
An organism's chemical reactions.
Metabolic pathways: alter molecules in a series of steps.
Enzymes selectively catalyze each step, and their activity is regulated to maintain a balance of supply and demand.
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Metabolism Overview:
A cell's metabolism is a roadmap of chemical reactions, including various biosynthetic and degradation pathways.
Mention of various metabolic pathways such as Glycan biosynthesis, amino acid metabolism, carbohydrate metabolism, and others.
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Redox Reactions:
Oxidation and reduction processes where:
Compound A is reduced and compound B is oxidized.
Oxidation: losing electrons
Reduction: gaining electrons
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Coupled Reactions:
Release energy ultimately used to synthesize ATP.
Oxidation = lose electron; Reduction = gain electron
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Bioenergetics:
Study of how living organisms utilize free energy.
Focuses on energy flow within living systems and relates to principles of chemistry, physics, and engineering.
Life requires free energy for various processes.
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Thermodynamics:
Study of energy transformations.
Systems in thermodynamics can be open (energy and matter exchanged) or closed (isolated from surroundings).
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First Law of Thermodynamics:
Energy can be transferred and transformed, but cannot be created or destroyed.
Example: Roller coaster converting kinetic to potential energy and vice versa.
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Open Systems:
Organisms are open systems absorbing energy and releasing heat and metabolic waste products.
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Energy Transformation:
Potential energy in food is converted to energy available for cellular work.
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Second Law of Thermodynamics:
Any spontaneous chemical or physical change increases the disorder of the universe (entropy).
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Entropy Illustration:
Closure in systems filled with inert gases demonstrates disorder when the barrier is removed.
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Entropy - Illustrative Example:
Explanation of seating arrangements of students at desks demonstrating entropy and disorder.
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Summary of potential states and the concept of indistinguishable arrangements to explain entropy.
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Ordered vs. Disordered States:
Disordered states are more likely than ordered states, illustrating the tendency towards entropy.
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Free Energy:
Portion of a system’s energy that can perform work.
Calculated as free energy/Gibbs free energy with formula: ∆G = ∆H - T∆S.
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Spontaneity of a System:
Free energy criteria:
Spontaneous processes occur without outside help.
Non-spontaneous processes require energy addition.
Spontaneous increases stability, while non-spontaneous decreases stability.
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Using Free Energy:
Measurement of system stability through free energy calculations.
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Closed Systems:
Example: A closed hydroelectric system that reaches metabolic equilibrium (delta G = 0) indicates death.
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Open Systems:
Cells maintain disequilibrium, allowing continual work due to constant material flow.
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Spontaneous vs. Non-Spontaneous:
Spontaneous: ΔG = negative.
At equilibrium: ΔG = 0, leading to no work being done.
Non-spontaneous: ΔG = positive, requiring energy input.
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Cellular Respiration:
Reaction: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy
Energy is used to synthesize ATP (ΔG = -686 kcal/mol).
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Magnitude of ΔG in Cellular Respiration:
Reaction releases 686 kcal of energy for cellular work, products have 686 kcal less energy than reactants.
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Exergonic Reactions:
Catabolic processes that release free energy (ΔG is negative).
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Endergonic Reactions:
Absorb free energy from surroundings, storing energy (ΔG is positive).
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Intermediary Metabolism:
All reactions involved in storing and generating metabolic energy and their utilization in cellular processes.
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Exergonic and Endergonic Reactions:
Based on free energy, these reactions are stepwise; metabolism utilizes different chemical reactions organized into catabolic and anabolic pathways.
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Energy Flow in Metabolism:
Energy released from catabolic pathways drives anabolic reactions, demonstrating energy transformation capability in living organisms.
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Catabolism (Yields ATP):
Describes substrates and transformations leading to the production of ATP.
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Processes in Catabolism:
Includes breakdown of proteins, polysaccharides, lipids, and simplifies into substrates usable for energy production (e.g., Citric Acid Cycle, Electron Transport).
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Anabolism (Uses ATP):
Synthesis of larger reduced molecules from smaller oxidized molecules using ATP.
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Processes in Anabolism:
Involves synthesis of proteins, polysaccharides, lipids, and other biomolecules using energy from ATP.
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ATP (Adenosine Triphosphate):
Described as the universal energy carrier and its structure involving adenine and phosphate groups.
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Hydrolysis of ATP:
Reaction: ATP + H2O → ADP + P (exergonic process)
Details hydrolysis mechanism and products formed.
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Dehydration of ADP:
Reaction: ADP + P → ATP + H2O (endergonic process).
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Diagram of ATP Structure:
Components include nitrogen-containing base, high-energy bonds, phosphate groups, and ribose sugar.
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Overview of Cellular Respiration Processes:
Provides pathways and processes involved in energy generation, emphasizing glycolysis, citric acid cycle, and electron transport chain.