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How energy and enzyme catalysts relate to exothermic and endothermic reactions.
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Energy and Physiology
• Energy is the capacity to do work or cause change
• Organisms store energy in organic molecules as chemical energy
• Free energy is the portion of energy released during chemical reactions that is available to do work
Energy and Nutrients
Energy and NutrientsOrganisms obtain their energy through Autotrophy or Heterotrophy
Autotrophs are organisms capable of producing their own food
Heterotrophs are organisms that must obtain food from an outside source
by consuming another organism
Chemical Reactions Make Life Possible!
Autotrophs Heterotrophs and Autotrophs
The Law of Conservation of Energy (1st Law of Thermodynamics)
• Energy cannot be created or destroyed, but it can change form
• The total energy of the universe is constant
• Organisms cannot create their own energy but must obtain it from an outside source
The Second Law of Thermodynamics
• There is a natural tendency towards disorder “entropy”
• Energy is required to resist entropy
• An organism must be well organized to remain alive and grow (Organization requires energy)
Chemical Reactions Proceed as Follows:
Reactants ProductsEnergy must be added to “activate” the reaction and break the bonds between atoms
Activation Energy
Metabolism and Energy Transfer
Types of ReactionsEndothermic
Stores energy in bonds
Ex. is photosynthesis
Types of ReactionsExothermic
Energy is released by breaking bonds
Ex. is cellular respiration
Energy Curve of an Uncatalyzed Exothermic Reaction
Energy of Reactants
Energy of Products
Activation Energy
In cases like this (High AE), reactions would occur too slowly to support life!!!
Catalysts speed up the rate of a reaction by lowering the activation energy needed to get the reaction going
Catalysts are not changed or used up during a reaction!
Catalysts
Protein molecules that act as catalysts
Specific to a Substance or Reaction
Speeds up Biological Reactions to 10,000,000,000 times faster
Enzymes
Bind to Specific Reactants to Form a complex
Reactants enzymes interact with are called Substrates
Substrate binds to the enzyme at a location called the Active Site
How Enzymes Work
E + S ES E + PCatalase
Breaks H2O2 into H2O and O2
Hydrogen Peroxide is Toxic to Cells
Catalase + H2O2 Complex Catalase + H2O + O2
Enzymatic Reactions
Induced Fit
Enzymes are named by taking either the name of the substrate or the action performed and adding the ending “ase”
DNA Polymerase
Lactase
Ligase
Naming Enzymes
Factors Effecting Enzyme Action
Metabolism: All the chemical activities in a cell or organism
Chemical Reactions in Organisms
Synthesis “building-up” reactions
Anabolism; biosynthesis
photosynthesis
dehydration synthesis
Decomposition
“breaking down” reactions
Catabolism
cellular respiration
digestion
hydrolysis
Decomposition reactions release free energy
Oxidation is the removal of electrons from a molecule
Bonds are broken and rearranged
Some energy of the original molecule is released as heat and free energy
Free energy is finally captured in ATP (adenosine triphosphate)
Energy Exchange in Cells
ATPATP is the cellular energy currency Can store/release small amounts of energy
The bond between the 2nd and 3rd phosphate is made or broken to exchange energy