Mr. Anderson at Early Bird Biology Class

Ch. 8 – Metabolism Slide 4 Metabolism is the totality of an organism’s chemical reactions

An Introduction to Metabolism I. Thermodynamics: The study of energy exchanges (transformations) A.First Law of Thermodynamics: Energy can not be created or destroyed. Energy is constant but can be transformed from one form to anotherFirst Law of Thermodynamics: B.Second Law of Thermodynamics: Any transfer of energy results in a loss of useable energy (heat/entropy/increasing disorder)Second Law of Thermodynamics: Potential EnergyKinetic Energy Entropy “Energy always flows downhill”

Energy Exchanges can be expressed by the equation: G = H - T S (Delta) = (Final State) - (Initial State) G = Free Energy Exchange/capacity to do work H = Amount of total energy available in the system T = Temperature S = Amount of Entropy (disorder / stability) Gravitational Motion Diffusion Molecular Motion Chemical Reactions Initial State: 1.More Free Energy in System (H) 2.Less stable / Lower Entropy (S) 3.Greater Work Capacity (G) Spontaneous Change 1.Free Energy Decreases 2.Increasing stability 3.Free energy released to do work Final State: 1.Less Free Energy in System (H) 2.More Stable / Higher Entropy (S) 3.Less Work Capacity (G) + G - S - G + S Slide 1

Bioenergetics: Energy Exchanges in Living Organisms 1.Energy Exchanges always involve interactions of Electrons 2.Energy is used/released as electrons rearrange in “new” shellsEnergy AB + CD AC + BD AC + BD AB + CD Endergonic Exergonic Spontaneous Non-spontaneous + G - G Increasing Entropy Decreasing Entropy Anabolic Catabolic Energy Released Energy Required Cell Respiration Photosynthesis 1.Exergonic1. Endergonic 2.Spontaneous2. Non-Spontaneous 3.- G3. + G 4.Increasing Entropy 4. Decreasing Entropy 5.Catabolic5. Anabolic 6.Energy Released6. Energy Required 7.Cell Respiration7. Photosynthesis Metabolism Vocab AB + CD AC + BD Energy Output AC + BD AB + CD Energy Input

Energy Coupling Energy Coupling - The Link between Anabolism and Catabolism; using an exergonic process to drive an endergonic process Energy Required 1.ATP is the “energy coupler” 2.The structure of ATP allows the transfer of a phosphate that will increase the energy level of molecules through the process of phosphorylation.The structure of ATP phosphorylation. ATP AC + BD AB + CD P - AC + BD ADP P AB + CD

Place the words below on the appropriate side of the ATP   ADP cycle Phosphate Added Phosphate removedEndergonic ExergonicTransport workChemical work Synthesis workAnabolic Catabolic + G - GDehydration Synthesis HydrolysisIncreasing EntropyDecreasing Entropy Kinetic EnergyPotential EnergyEnergy Rich Energy Poor ADP Phosphorylated Other molecule phosphorylated ATP ADP Phosphate Added Phosphate Removed Endergonic Exergonic Transport Work Chemical Work Synthesis Work Anabolic Catabolic + G - G Dehydration synthesis Hydrolysis Increasing Entropy Decreasing Entropy Potential Energy Kinetic Energy Energy Rich Energy Poor ADP Phosphorylated Other Molecules Phosphorylated ENERGY

Examples of how ATP drives Transport and Mechanical Work ATP ADP Motor protein Slide 7

Enzymes: Proteins that make life possible 1. All chemical reactions need an energy push to start the reactionpush 2. Enzymes unique structure lowers the energy of activationenergy of activation AB + CD AC + BD Energy required without enzyme Energy required with enzyme Total energy given off by reaction

Important Enzyme Concepts Substrate : The substance(s) that is acted on by the enzyme Product: The substance(s) that results from enzyme activity Active Site: Active Site: The part of the enzyme that bonds to the substrate 1. Enzymes are not used up in the reaction 2. Enzymes are specific for their substrates 3. Enzymes can be catabolic or anabolic 4. Enzymes are proteins. Their active sites can be denatured and be non-functional. (pH and temperature)denatured 5. As Proteins, enzymes are coded by the DNA. Gene traits are due to the enzymes an organism makes H2OH2O Substrate Products Enzyme- Substrate Complex Active Site Important Enzyme Concepts Sucrose Sucrase Glucose Fructose (Sucrose) (Glucose + Fructose) Lock and Key Induced Fit Substrate and enzyme fit perfectly together

Enzyme Inhibitors Substrate Normal Interaction Active Site Enzyme Competitive Inhibition Inhibitor fits into active site and “competes” with the real substrate [influenced by concentration of substrate] Non-Competitive Inhibition Inhibitor bonds to enzyme away from the active site; changes shape of active site (can be part of feedback inhibition) [not influenced by concentration of substrate] Inhibitor

(Negative) Feedback Inhibition: Initial Substrate (threonine) Intermediate A Intermediate D Intermediate C Intermediate B Enzyme 2 Enzyme 3 Enzyme 4 Enzyme 5 End Product (isoleucine) Feedback Inhibition Isoleucine fits in allosteric site or non- competitive site Active site no longer bonds to threonine End product switches off its own production

*Many normal enzymes need non-protein ‘helpers’ to become active and function Cofactors – Coenzymes – Bind to place other than active site; inorganic like zinc, iron, copper Cofactors that are organic; vitamins like C, D, E

Allosteric Enzymes: Contain allosteric sites that affect enzyme activity. Molecules bonding to the allosteric sites can activate or inhibit. Many allosteric enzymes are involved in negative feedback pathways Active FormInactive Form ActivatorInhibitor Active sites

Cooperativity: As a substrate binds to an enzyme, the enzyme changes shape (induced fit) allowing other active sites to bind to the substrate Inactive form Active form Substrate Active site with greatest affinity to substrate New active sites are made available

How Phosphorylation Transfers Energy Slide 5

The Structure and Function of ATP Structure Function Slide 5

Slide 1 1 st Law of Thermodynamics Transformation #1 Transformation #2 100 Energy Units aaa Transformations 100 Energy Units

2 nd Law of Thermodynamics 100 units 50 units25 units 50 units 25 units Slide 1

A spontaneous chemical reaction will occur…but how long will it take? Sucrose (C 12 H 22 O 11 ) Slide 9

Space-filling model of Active Site Slide 10

Environmental factors affecting enzyme activity Slide 10