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Chapter 8 An Introduction To Metabolism
Metabolism u The totality of an organism’s chemical processes. u Concerned with managing the material and energy resources of the cell.
Catabolic Pathways u Pathways that break down complex molecules into smaller ones, releasing energy. u Example: Respiration
Anabolic Pathways u Pathways that consume energy, building complex molecules from smaller ones. u Example: Photosynthesis
Energy u Ability to do work. u The ability to rearrange a collection of matter. u Forms of energy: u Kinetic u Potential u Activation
Kinetic Energy u Energy of action or motion.
Potential Energy u Stored energy or the capacity to do work.
Activation Energy u Energy needed to convert potential energy into kinetic energy. Potential Energy Activation Energy
Energy Transformation u Governed by the Laws of Thermodynamics.
1st Law of Thermodynamics u Energy can be transferred and transformed, but it cannot be created or destroyed. u Also known as the law of “Conservation of Energy”
2nd Law of Thermodynamics u Each energy transfer or transformation increases the entropy of the universe.
Entropy u Measure of disorder.
Summary u The quantity of energy in the universe is constant, but its quality is not.
Question? u How does Life go against Entropy? u By using energy from the environment or external sources (e.g. food, light).
Free Energy u The portion of a system's energy that can perform work.
Free Energy G = H - TS G = free energy of a system H = total energy of a system T = temperature in o K S = entropy of a system
Free Energy of a System u If the system has: u more free energy u it is less stable u It has greater work capacity
Spontaneous Process u If the system is unstable, it has a greater tendency to change spontaneously to a more stable state. u This change provides free energy for work.
Free Energy Changes
Chemical Reactions u Are the source of energy for living systems. u Are based on free energy changes.
Reaction Types u Exergonic: chemical reactions with a net release of free energy. u Endergonic: chemical reactions that absorb free energy from the surroundings.
Biological Examples u Exergonic - respiration u Endergonic - photosynthesis
Cell - Types of Work u Mechanical - muscle contractions u Transport - pumping across membranes u Chemical - making polymers
Cell Energy u Couples an exergonic process to drive an endergonic one. u ATP is used to couple the reactions together.
ATP u Adenosine Triphosphate u Made of: - Adenine (nitrogenous base) - Ribose (pentose sugar) - 3 phosphate groups
Adenine Ribose Phosphates
Key to ATP u Is in the three phosphate groups. u Negative charges repel each other and makes the phosphates unstable.
ATP u Works by energizing other molecules by transferring phosphate groups.
ATP vs Food u ATP: u Renewable energy resource. u Unstable bonds u Food: u Long term energy storage u Stable bonds
ATP Cycles u Energy released from ATP drives anabolic reactions. u Energy from catabolic reactions “recharges” ATP.
ATP in Cells u A cell's ATP content is recycled every minute. u Humans use close to their body weight in ATP daily. u No ATP production equals quick death.
Enzymes u Biological catalysts made of protein. u Cause the rate of a chemical reaction to increase.
Enzymes u Lower the activation energy for a chemical reaction to take place.
Enzyme Terms u Substrate - the material the enzyme works on. u Enzyme names: Ex. Sucrase - ase name of an enzyme 1st part tells what the substrate is. (Sucrose)
Enzyme Name u Some older known enzymes don't fit this naming pattern. u Examples: pepsin, trypsin
Active Site u The area of an enzyme that binds to the substrate. u Structure is designed to fit the molecular shape of the substrate. u Therefore, each enzyme is substrate specific.
Homework u Read chapter 8, 41 u Exam 2 – this week, no broadcast on Thursday u Chapter 8 – Fri. 10/10 u Chapter 41 – Mon. 10/20
Models of How Enzymes Work 1. Lock and Key model 2. Induced Fit model
Lock and Key Model u Substrate (key) fits to the active site (lock) which provides a microenvironment for the specific reaction.
Induced Fit Model u Substrate “almost” fits into the active site, causing a strain on the chemical bonds, allowing the reaction.
Substrate Active Site
Enzymes u Usually specific to one substrate. u Each chemical reaction in a cell requires its own enzyme.
Factors that Affect Enzymes u Environment u Cofactors u Coenzymes u Inhibitors u Allosteric Sites
Environment u Factors that change protein structure will affect an enzyme. u Examples: u pH shifts u temperature u salt concentrations
u Cofactors: non-organic helpers required for the proper function of enzymes. u Nonprotein ions or molecules u Ex. Fe, Zn, Cu u NADH u Coenzyme Q
u Coenzymes: organic helpers to enzymes. Ex. vitamins
Enzyme Inhibitors u Competitive - mimic the substrate and bind to the active site. u Noncompetitive - bind to some other part of the enzyme.
Allosteric Regulation u The control of an enzyme complex by the binding of a regulatory molecule. u Regulatory molecule may stimulate or inhibit the enzyme complex.
Control of Metabolism u Is necessary if life is to function. u Controlled by switching enzyme activity "off" or "on” or separating the enzymes in time or space.
Types of Control u Feedback Inhibition u Structural Order
Feedback Inhibition u When a metabolic pathway is switched off by its end- product. u End-product usually inhibits an enzyme earlier in the pathway.
Structural Order u Separation of enzymes and metabolic pathways in time or space by the cell's organization. u Example: enzymes of respiration
Summary u Recognize that Life must follow the Laws of Thermodynamics. u The role of ATP in cell energy. u How enzymes work.
An Introduction to Metabolism
Introduction to Metabolism Chapter 6. Metabolism - sum of organism’s chemical processes. Enzymes start processes. Catabolic pathways release energy (breaks.
Metabolism: Energy and Enzymes Chapter 6. 2 Flow of Energy Energy: the capacity to do work -kinetic energy: the energy of motion -potential energy: stored.
Energetics and metabolism biology 1. The chemistry of life is organized into metabolic pathways Organisms transform energy The energy of transformation.
Thermodynamics and Metabolism. 2 Metabolism Metabolism: all chemical reactions occurring in an organism Anabolism: chemical reactions that expend energy.
The Basis of metabolism The Basis of metabolism Forms of Energy Forms of Energy Laws of Energy Transformation Laws of Energy Transformation Structure,
Chapter 8: Metabolism Metabolism Metabolism – all of the chemical reactions in an organism - A metabolic pathway begins with a specific molecule and.
1 BIOENERGETICS Energy Flow. 2 What is Bioenergetics? energyliving systems organisms The study of energy in living systems (environments) and the organisms.
Chapter 8~ An Introduction to Metabolism. Metabolism Metabolism Metabolism: The totality of an organism’s chemical processes; managing the material and.
Introduction to Metabolism Chapter 6. Metabolism u The totality of an organism’s chemical processes. u Concerned with managing the material and energy.
Chapter 8 An Introduction To Metabolism. Metabolism.
Metabolism Chapter 8 Review.
Enzymes Functions and Control. Enzyme Terms Substrate - the material and enzyme works on. Enzyme names: Ex. Sucrase - ase name of an enzyme - ase.
2.a.1 – All living systems require constant input of free energy ( ). 4.b.1 – Interactions between molecules affect their structure and function.
An Introduction to Metabolism Bioenergetics Enzymes.
Unit 1 – The Chemistry of Life Chapter 6~ An Introduction to Metabolism.
Chapter 8 An Introduction To Metabolism. Metabolism u The totality of an organism’s chemical processes. u Concerned with managing the material and energy.
Ch. 8: METABOLISM Cell = chemical factory Thousands of reactions per second Synthesis of polymers Digestion of polymers Production/transfer of energy.
Energy, Metabolism, and Enzymes Ch 6 Baboon Ch Bat - Energy: the ability to do work - Two major types of energy 1. Kinetic - energy of motion -
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