1. METABOLISM: ENERGY AND ENZYMES

2. Metabolism: Energy and enzymes  Types of Energy  Solar: ultimate source for living organisms  Kinetic: energy of motion  Potential: stored energy; capacity to do work Chemical energy: form of potential energy that includes the food we eat  Mechanical: sum of kinetic and potential energy stored in a system

3. Metabolism: Energy and Enzymes  Thermodynamics  1 st Law: conservation of energy  Energy can’t be created nor destroyed  Can only be changed from one form to another  2 nd Law of Thermodynamics  Energy can’t be changed from one form to another without a loss of useable energy

4. Metabolism: Energy and Enzymes  Cells and Entropy  Entropy indicates relative amount of disorganization  According to 2 nd law entropy always increasing in universe  WHY?  It is more stable that way

5. Metabolism: Energy and Enzymes  Metabolism: sum of all chemical reactions that occur in a cell  A reaction will occur spontaneously if it increases entropy  Free energy (G) is the amount of energy available after a chemical reaction has occurred-look at it terms of potential energy  The change in free energy ( Δ G) is calculated by subtracting the (G) of the reactants from that of the products  ( Δ G) = G products – G reactants  A (- Δ G) means the products have less free energy than the reactants

6. Metabolism: energy and enzymes  Exergonic Reactions- ( Δ G) is negative and energy is released  Endergonic Reactions- ( Δ G) is positive and the products have more free energy; only occur with an input of energy (examples: protein synthesis, muscle contractions)  Animation Animation

7. Metabolism: Energy and Enzymes  ATP: Energy currency for the cell  ATP is a nucleotide composed of  Adenine (nitrogen base)  Ribose (5-carbon sugar)  3 Phosphate groups  ATP is generated from ADP + P continuously  This is an efficient method of energy transfer in biological systems

8. Metabolism: Energy and Enzymes  The amount of energy released when ATP is hydrolyzed is approx. 7.3 kcal/mole  Functions of ATP  Chemical work: synthesizing macromolecules  Transport work: transport across membranes  Mechanical work: muscle contraction, cilia/flagella movement

9. Metabolism: Energy and Enzymes  Coupled Reactions Coupled Reactions  The energy released by an exergonic reaction is used to drive an endergonic reaction  ATP breakdown is often coupled to cellular reactions that require an input of energy

10. Metabolism: Energy and Enzymes  Metabolic pathways  A series of linked reaction that are highly structured and organized to conserve energy  These pathways are structured with the help of enzymes

11. Metabolism: Energy and Enzymes  Enzymes: protein molecules that function as catalysts and speed up chemical reactions  Enzymes contain an active site; the site on the protein where the substrate binds  Substrates: reactants in an enzymatic reaction  Enzyme-substrate complex: the temporary configuration of substrate bound to the enzyme  Animation Animation

12. Metabolism: Energy and Enzymes

13.  Energy of Activation: the energy that must be added to cause molecules to react  Animation: enzyme basics Animation: enzyme basics  Enzymes act by lower energy of activation  Δ G isn’t changed

14. Metabolism: Energy and Enzymes  Factors affecting enzyme speed  Substrate concentration: generally speed increases as substrate conc. increase  Temperature and pH: increased temp increases speed  Too high temp can cause denaturation (disfigured enzyme)  Enzyme concentration:  Enzyme cofactors: vitamins  Enzyme inhibition – feedback inhibitionfeedback inhibition  http://www.kscience.co.uk/anim ations/model.swf http://www.kscience.co.uk/anim ations/model.swf  Denaturation Denaturation