Lecture 2 Outline (Ch. 8, 9) • Energy • Thermodynamics • Metabolism and Chemical Reactions • V. Cellular Energy - ATP • Enzymes & Regulation • Cell Respiration • Redox Reactions • Glycolysis • Coenzyme Junction • VII. Preparation for next Lecture
Energy What is Energy? Where does energy on earth come from originally? [equivalent of 40 million billion calories per second!] Types of Energy: - Kinetic Energy = energy of movement - Potential = stored energy
Energy Potential Energy Kinetic Energy Thermodynamics – study of energy transformation in a system Potential energy can be converted to kinetic energy (& vice versa)
Thermodynamics Laws of Thermodynamics: Explain the characteristics of energy • 1st Law: • Energy is conserved • Energy is not created or destroyed • Energy can be converted (Chemical Heat) 2nd Law: • During conversions, amount of useful energy decreases • No process is 100% efficient • Entropy (measure of disorder) is increased Energy is converted from moreordered to less ordered forms
Metabolism and Energy Cells convert molecules chemically using cellular energy.
Metabolism Metabolism – chemical conversions in an organism Metabolic reactions: All chemical reactions in organism • Anabolic = builds up molecules Catabolic = breaks down molecules Two Types of Metabolic Reactions
Chemical Reactions + + Reactants Products • Chemical Reaction: • Process that makes and breaks chemical bonds • Two Types of Chemical Reactions: • 1) Exergonic = releases energy • 2) Endergonic = requires energy
Metabolism • Metabolic reactions: • Chemical reactions in organism Two Types of Metabolic Reactions: • Anabolic = build up Catabolic = break down Exergonic = release energy Endergonic = requires energy
Chemical Reactions Glucose CO2 + H20 CO2 + H20 Glucose -ΔG +ΔG (or 0) release energy intake energy spontaneous non-spontaneous • Exergonic reaction • Endergonic reaction
Question/Recall: Which has more order? Stores more energy? Polymer or Monomer, Diffused or Concentrated H+? What is relationship between order and energy?
What type of energy is stored in a covalent bond? A. Kinetic energy B. Diffused energy C. Heat energy D. Potential energy E. Conventional energy
Cellular Energy - ATP • ATP = adenosine triphosphate • ribose, adenine, 3 phosphates • last (terminal) phosphate - removable Be able to diagram ATP!
ATP + H2O ADP + Pi Cellular Energy - ATP • ATP hydrolyzed to ADP • Exergonic • Energy released, used in another reactions (endergonic)
Cellular Energy - ATP • ATP regenerated • cells power ATP generation by coupling to exergonic reactions Like cellular respiration!
Making ATP from ADP + Pi is… • Exergonic because it releases energy • Endergonic because it requires energy • Exergonic because it requires energy • Endergonic because it releases energy
Chemical Reactions • Chemical Reactions: • Like home offices – tend toward disorder • Endergonic – energy taken in; Exergonic – energy given off Exergonic Endergonic
Chemical Reactions Nucleus Nucleus Repel Activation Energy Activation Energy Nucleus Nucleus Repel Activation Energy: Energy required to “jumpstart” a chemical reaction • Must overcome repulsion of molecules due to negative • charged electrons
Chemical Reactions • Exergonic Reaction: • Reactants have more energy than products Activation energy: Make sugar and O2 molecules collide sugar + O2 water + CO2 “Downhill” reaction
Respiration (ch. 9) preview Cellular Respiration Equation: C6H12O6 + O2 CO2 + H2O You will need to KNOW this equation.
Chemical Reactions and Enzymes Enzymes • lower activation energy only for specific reactions • cell chooses which reactions proceed! enzymes: cannot make rxns go that wouldn’t otherwise Cannot change endergonic into exergonic rxns Dospeed up rxns that would occur anyway
Enzymes • Enzymes – control rate of chemical reaction • sucrase – enzyme sucrose breakdown “-ase” enzyme • sucrase – catalyst -speed up rxn, but not consumed
Enzymes • enzyme – specific to substrate • active site – part of enzyme -substrate • binding tightens fit – induced fit • form enzyme-substrate complex • catalytic part of enzyme: converts reactant(s) to product(s)
Enzymes • Enzymes lowers EA by: -template orientation -stress bonds • substrate(s) enter -microenvironment • enzyme reused • product(s) formed • What factors might affect enzyme activity?
Enzymes • inhibitors: binds & blocks active site binds allosteric site – alters conformation • Drug – blocks HIV enzyme at the active site
If a competitive inhibitor is in an enzyme reaction, can you reverse the inhibition by adding more substrate? • Yes • No • I’m not sure • Wait, what’s a competitive inhibitor?
Cellular Respiration Overall purpose: • convert food to energy • animals AND plants • complementary to photosynthesis
Cellular Respiration: (Exergonic) Cellular Respiration • catabolizes sugars to CO2 • requires O2 • at mitochondrion
Redox Reactions • as part of chemical reaction, e- are transferred • e- transfer = basis of REDOX reactions (reduction) (oxidation)
Redox Reactions Use “H rule” for reactions in this class Reactant with more H’s = e donor, will be oxidized Reactant with more O’s = e acceptor, will be reduced ZH2 + O2 yields ZO + H2O • follow the H, e- move with them
Self-Check Oxygen ZH2
Redox Reactions Equation for respiration
Redox Reactions • transfer of e- to oxygen is stepwise
• glucose NADH ETC O2 (makes H2O) Redox Reactions • e- moved by NAD/H (from niacin/vit B3) • NADH carry e- (reduced!) • NAD+ not carrying e- (oxidized!) Where do e- come from? Where do e- go?
In this equation is NAD+ to NADH oxidized or reduced? NAD+ + H+ + 2e- NADH • Reduced, it gained electrons • Oxidized, it gained electrons • Reduced, it lost electrons • Oxidized, it lost electrons
Steps of Respiration • Steps of respiration: 1. glycolysis 2 CO2 Coenzyme Junction 2. Citric acid cycle 4 CO2 3. ETC 4. Chemiosmosis
Cellular Respiration • Stages of respiration: 1. Glycolysis – prep carbons
Cellular Respiration 1. Glycolysis • 1 glucose (6C) 2 pyruvate (3C) • Keep track of: - inputs - ATP - NAD+/NADH - CO2 and H2O - outputs • eukaryotes AND prokaryotes
Glucose Glucose-6-phosphate ATP 2 1 ADP Fructose-6-phosphate Glucose-6-phosphate Glycolysis
ATP Fructose- 1, 6-bisphosphate ADP 4 5 Glyceraldehyde- 3-phosphate Dihydroxyacetone phosphate Glycolysis
2 ADP 2 ATP Phosphoenolpyruvate 2 2 ADP 10 2 ATP Pyruvate 2 Glycolysis Step not shown
How many NET ATP are produced by glycolysis? • one • two • four • six • eight
Cellular Respiration Glycolysis -inputs: 1 Glucose 2 ATP -outputs: 2 pyruvate 4 ATP (2 net) 2 NADH CO2 = none yet (2 H2O) Where do the outputs go?
Energy production Mitochondria • energy from nutrients ATP
Cellular Respiration Coenzyme Junction • 2 pyruvate (3C) 2 Acetyl CoA (2C) • pyruvate joins coenzyme A (from vitamin B5) • 2 carbons lost (as CO2) • 2 NAD+ NADH
Things To Do After Lecture 2… • Reading and Preparation: • Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms. • Ch. 8 Self-Quiz: #1-6 (correct answers in back of book) • Read chapter 9, focus on material covered in lecture (terms, concepts, and figures!) • Skim next lecture. • “HOMEWORK” (NOT COLLECTED – but things to think about for studying): • Describe the relationship between exergonic/endergonic, catabolic/anabolic, and “uphill”/”downhill” chemical reactions • Diagram one molecule of ATP and how ADP is different • Cut apart the boxes on the previous sheet – match up three (name, energy balance, basic reaction) for glycolysis and three for the coenzyme junction • Place the following molecules in order for when they are used/created during glycolysis: fructose-6-phosphate, glucose, glucose-6-phosphate, pyruvate, glyceraldehyde-3-phosphate