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Chapter 8: An Introduction to Metabolism - Coggle Diagram
Chapter 8: An Introduction to Metabolism
Metabolism
Pathways
Metabolism
The totality of an organisms chemical reactions
Catabolic Reactions + Anabolic Reactions = Metabolism
An emergent property of life that arises from orderly interactions between molecules
Metabolic Pathways
A series of chemical reactions that either builds a complex molecule (anabolic reactions) or breaks down a complex molecule to simple molecules (catabolic reactions)
Catabolic Pathway
A metabolic pathway that releases energy by breaking down complex molecules to simpler molecules
Also known as the Breakdown Pathway
Ex: Cellular Respiration
Breaks down glucose and other organic fuels in the presence of oxygen to carbon dioxide and water
Anabolic Pathway
A metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules
Also known as Biosynthetic Pathway
Ex: Synthesis of Amino Acids from simpler molecules and Synthesize of a Protein from Amino Acids
Energy released from downhill reactions of catabolic pathways can be stored and then used to drive uphill reactions of anabolic pathways
Forms of Energy
Energy
The capacity to cause change; can be used to do work; move against opposing forces (gravity and friction)
Can be converted from one form to another
4 Main Forms
Kinetic, Chemical, Thermal, and Potential
Kinetic Energy
Energy associated with motion
Moving objects can perform work by imparting motion to other matter
Thermal Energy
Is Kinetic Energy associated with random movement of atoms of molecules
Heat
Thermal energy is transferred from one object ti another
Light Energy
Energy that can be harnessed to perform work
Ex: Powering Photosynthesis
Potential Energy
Energy that matter possesses because of its location or structure
Ex: Molecules
Possess energy due to the arrangement of electrons in the bonds between their atoms
Chemical Energy
Potential energy available for release in a chemical reaction
Ex: Breakdown of Glucose
In the catabolic breakdown of the complex molecule Glucose, there is high chemical energy
Laws of Energy
Thermodynamics
The study of energy transformation in a collection of matter
Isolated System
Is unable to exchange energy or matter with its surroundings
Ex: Liquid in a Thermos Bottle
Open System
Is able to exchange energy or matter with its surroundings
Ex: Organisms/Humans
1st Law of Thermodynamics
The energy of the universe is constant
Also known as The Principle of Conservation of Energy
Energy can be transferred or transformed but can't be created or destroyed
Transformation
Energy can change forms; Doesn't create new energy
Ex: Bear catching food
A bear converts the chemical energy from food into kinetic energy as it moves
Transfer
-Movement of energy between a system and its surrounding
Ex: Photosynthesis
A plant absorbs sunlight
The chemical energy, converted during photosynthesis, is transferred through organisms as they consume the plants
2nd Law of Thermodynamics
During every energy transfer or transformation some energy is converted to thermal energy and lost as heat, becoming unavailable to do work
When energy is transferred some is lost as heat
Increase the entropy of the universe
Entropy
A measure of molecular disorder, or randomness
May decrease in a particular system as long as the total entropy of the system and surroundings increase
The more randomly arranged a collection of matter is, the greater its entropy
Spontaneous Processes
Occurs without extra energy input; can happen quickly or slowly
Increase entropy
Nonspontaneous Processes
Occurs only with additional energy
Decrease entropy
Free Energy
Free Energy
The portion of a system's energy that can do work when temperature and pressure are uniform throughout the system
ΔG=ΔH-TΔS
ΔG - Change in Gibbs Free Energy
A negative ΔG means it's a spontaneous reaction
Loses free energy and becomes more stable
A zero or positive ΔG means it's a nonspontaneous reaction
The higher G value, the more stable
ΔH - Change in Enthalpy
Enthalpy
The total energy of a system, including both internal energy and the energy required to make room for it by displacing its environment
T - Temperature
Temperature is measured in Kalvin (K)
ΔS - Change in Entropy
Equilibrium
The point of which forward and reverse reactions occur at the same rate, describes a state of maximum stability
True Equilibrium can't be reached
A system wouldn't be doing any work resulting in the possible death of the organism
A system can only be working TOWARDS equilibrium, but never reaches it
Reactions
Exergonic Reaction
Energy outward; proceeds with a net release of free energy to the surroundings
Characteristics
ΔG
The change in Gibbs Free Energy is negative
Reaction loses Free Energy
Spontaneity
Is a spontaneous reaction
|G|
Represents the maximum amount of work the reaction can perform
Endergonic Reaction
Energy inward; absorbs free energy from the surroundings
Characteristics
ΔG
The change in Gibbs Free Energy is zero and/or positive
Reaction stores Free Energy
Spontaneity
Is a nonspontaneous reaction
|G|
The quantity of energy required to drive the reaction
Enzymes
Enzyme
A macromolecule (typically protein) that acts as a catalyst to speed up a specific reaction
Decrease the activation energy of a reaction
Usually in the form of heat
Can't alter the ΔG, it can only speed up a reaction that would've eventually occurred
Catalysis
The process by which a catalyst selectively speeds up a reaction without itself being consumed
Catalyst
A chemical agent that speeds up a reaction without being consumed by the reaction
Activation Energy
The initial energy needed to break the bonds of the reactants
Enzyme-Substrate Complex
A temporary complex formed when an enzyme binds to its substrate molecule(s)
Substrate
The reactant on which an enzyme works
Enzymes are VERY specific
Known as Enzyme Specification
Saturated
When all enzymes are bonded to substrate, the enzyme is saturated
To speed up the reaction, add more enzymes
Active Site
The specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs
The conversion of substrate to product happens rapidly, and product is released from the active site
Each enzyme has an optimal temperature and pH
Cofactors
Nonproteins helpers that binds to the enzyme permanently, or reversibly with the substrate
Coenzymes
Organic cofactors
Competitive Inhibitor
A substance that reduces the activity of an enzyme by entering the active site in place of the substrate
They closely resemble the substrate and can bind to the enzyme's site
Are responsible for reducing the productivity of enzymes by blocking the substrates from entering the active site
Can be overcome by increasing the number of substrates
This is so more active sites become available allowing for more substrate molecules to bind than competitive inhibitors
Noncompetitive Inhibitor
A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme’s shape so that the active site no longer effectively catalyzes the conversion of substrate to product
Bind to another part of the enzyme, away from the active site
Responsible for reducing the productivity of enzymes by binding to another part of the enzyme and changing its shape
How to overcome
Increasing the concentration of enzymes to increase the number of active sites available to substrates
Allosteric Regulation
Regulation
Feedback Inhibition
A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway
Ex: Anabolic Pathway
Some cells use a five-step pathway to synthesize the amino acid isoleucine from threonine, another amino acid
As isoleucine accumulates, it slows down its own synthesis by allosterically inhibiting the enzyme for the first step of the pathway
Feedback inhibition thereby prevents the cell from making more isoleucine than is necessary and thus wasting chemical resources
Allosteric Regulation
The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site
Occurs when a regulatory molecule binds to a protein at one site and affects the protein's function at another site
Activation and Inhibition
Activation
The binding of an activator to a regulatory site stabilizes the shape that has functional active sites
Inhibition
The binding of an activator to a regulatory site stabilizes the shape that has functional active sites
Cooperativity
A substrate binding to one active site triggers a shape change in the enzyme that stabilizes the active form of all other sites
ATP
Structure and Hydrolysis of ATP
ATP Hydrolysis
The bonds between the phosphate groups of ATP can be broken by hydrolysis.
The terminal phosphate bond is broken by addition of a water molecule, a molecule of inorganic phosphate leaves the ATP, which becomes adenosine diphosphate (ADP)
Is an exergonic reaction
Because their hydrolysis releases energy, the phosphate bonds of ATP are sometimes referred to as high-energy phosphate bonds
Cellular work is powered by ATP Hydrolysis
Structure of ATP
ATP ( Adenosine Triphosphate)
Energy Coupling
ATP plays a role in this process
The use of an exergonic process to drive an endergonic process
Composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups
Also one of the nucleoside triphosphates used to make RNA
ATP and Work
3 Types of Work
Chemical Work
The pushing of endergonic reactions that would not occur spontaneously
Mechanical Work
The contraction of muscle cells, and the movement of chromosomes during cellular reproduction
Transport Work
The pumping of substances across membranes against the direction of spontaneous movement
ATP
Phosphorylation
The transfer of a phosphate group from ATP to another molecule
Typically used to power endergonic reactions
Phosphorylated Intermediate
A molecule (often a reactant) with a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule
The recipient molecule is more reactive (less stable with more energy) than the original molecule
Regeneration of ATP
Renewable Source
ATP is a renewable resource that can be regenerated by the addition of phosphate to ADP
Since the making of ATP from ADP and a phosphate group is a non-spontaneous reaction, it does require free energy to occur
Catabolic (exergonic) pathways, especially cellular respiration, provide the energy for the endergonic process of making ATP
ATP Cycle
A fundamental process in cellular metabolism that involves the continuous regeneration of ATP (adenosine triphosphate)
The shuttling of inorganic phosphate and energy