Transcript + Energy
Energy and Metabolism KEY WORDS: Energy Free Energy (ΔG) Potential energy Kinetic energy Enzyme Substrate Activation energy Exergonic reaction Endergonic reaction Catalyst ATP/ ADP Energy •The capacity to do work •Move matter Types of energy •Kinetic •Potential Question: __________ is an example of kinetic energy, and __________ is an example of potential energy. 1. 2. 3. 4. 5. Fire; a piece of wood A loaded gun; a flying bullet A rock on top of a hill; a rock rolling down the hill None of these are correct. All of these are correct. Chemical Energy •Stored in chemical bonds -high energy electrons •Some molecules store a lot of energy Carbos, lipids •Some molecules store much less Carbon dioxide, water Chemical Energy •Energy can be transferred/transformed Sugar + oxygen carbon dioxide + water + heat C6H12O6 + O2 CO2 + H2O + Energy First Law of Thermodynamics: Energy: neither created nor destroyed • Converted from one form to another • Exchanged between substances Second Law of Thermodynamics: All exchanges of energy increase the entropy of the universe Entropy: •Disorder or randomness of a system •Heat is most disorganized form of energy •Reactions that ↑ entropy happen spontaneously & release energy Two laws of thermodynamics Energy Transformed Exergonic Reactions •Release energy •“Spontaneous” •Usually breakdown of complex molecules Endergonic Reactions •Usually involve synthesis of complex molecules •Not “Spontaneous” 6CO2 + 6H2O + Energy •Require energy C6H12O6 + 6O2 Question: Which of the following reactions is endergonic? 1. 2. 3. 4. CO2 and H2O Glucose Amino acids Proteins Triglycerides Fatty acids Ions moving across membrane from an area of high concentration to an area of low concentration. Question: Which of the following reactions releases energy? 1. 2. 3. 4. CO2 and H2O Glucose Amino acids Proteins Triglycerides Fatty acids Ions moving across membrane from an area of high concentration to an area of low concentration. Coupled Reactions Exergonic provides energy for the endergonic Exergonic glucose Energy CO2 + H2O Endergonic Energy Amino acids Protein Living organisms Metabolism •All chemical reactions in an organism Anabolism Catabolism Living organisms •Capture energy to drive chemical reactions. •Convert “raw” energy into usable form ATP •Sunlight, food Energy Energy The structure and hydrolysis of ATP ATP: the Cell’s Rechargeable Battery • ATP energy ADP charged battery dead battery • This energy can then be used to run an energy requiring reaction. The ATP cycle According to the first law of thermodynamics, energy 1. is never lost or gained, but is only transformed 2. always requires an ultimate source such as the sun 3. can never be gained, but can be lost 4. can never really be harnessed 5. can never be transformed Each time there is a chemical reaction, some energy is exchanged. According to the second law of thermodynamics, with each exchange 1. 2. 3. 4. 5. Some energy is lost, but other energy is created. Some energy must come from the sun. Some energy is transformed into heat. Energy is gained for future use. Some energy is permanently and completely destroyed. ATP stores energy in the form of 1. 2. 3. 4. 5. mechanical energy heat complex carbohydrates chemical bond energy amino acids The complexity of metabolism Equation: Gibb’s Free Energy ΔG = ΔH – TΔS Energy available for work All energy Energy NOT available for work The relationship of free energy to stability, work capacity, and spontaneous change Energy changes in exergonic and endergonic reactions Energy profile of an exergonic reaction Disequilibrium and work in closed and open systems Is ΔG for an exergonic reaction positive or negative? What is the difference between: Anabolism Catabolism Metabolism From an energy perspective, when is equilibrium reached? Enzymes KEY WORDS: Enzyme Activation energy Catalyst Substrate Active site Induced fit Coenzyme Allosteric site Competitive inhibitor Noncompetitive inhibitor Feedback inhibition Enzymes and Shape Active Site Induced fit: “Handshake” between substrate and enzyme Activation Energy Activation Energy Net Energy Released Enzymes •Proteins that speed up chemical reactions (catalysts) •Lower activation energy for a reaction Enzyme reactions can be simplified as: E+S ES E +P • S = Substrates (reactants) enter reaction. • P = Product (what you get at the end) result • E = Enzymes mediate specific steps sucrase sucrose + H2O glucose + fructose The catalytic cycle of an enzyme Enzymes Key Points: •Catalyze reactions •Don’t change reactions •Same net release/use of energy •Enzymes are not changed by reaction •Each enzyme catalyzes a specific chemical reaction Enzymes lower the barrier of activation energy Which of the following will lower the activation energy of a reaction in a cell? 1. 2. 3. 4. 5. lowering the temperature lowering the pressure using an enzyme changing the amount of the reactants supplying ATP Which of the following will lower the activation energy of a reaction in a cell? 1. 2. 3. 4. 5. lowering the temperature lowering the pressure using an enzyme changing the amount of the reactants supplying ATP Enzymes 1. accelerate specific chemical reactions 2. are not chemically altered by binding with a substrate 3. lower the activation energy of specific chemical reactions 4. all of the above 5. a and c only 4 Things that Affect Enzyme Activity 1. Substrate concentration 2. Enzyme concentration 3. pH 4. Temperature Shape of enzyme (Protein denatured) Environmental factors affecting enzyme activity Enzyme Regulation • Enzymes can be turned on and off • Regulated by other molecules in the cell • Examples: – Allosteric regulation – Feedback inhibition – Inhibitors Inhibition of enzyme activity Allosteric regulation of enzyme activity Feedback inhibition If an enzyme solution is saturated with substrate, the most effective way to obtain an even faster yield of products is: a) b) c) d) e) Add more enzyme Heat the solution Add more substrate Add an allosteric inhibitor Add a noncompetitive inhibitor An enzyme accelerates a metabolic reaction by a) Altering the overall free energy change for the reaction b) Making an endergonic reaction occur spontaneously c) Lowering the activation energy d) Pushing the reaction away from equilibrium e) Making the substrate molecule more stable Some bacteria are metabolically active in hot springs because a) They are able to maintain a cooler internal temperature b) High temperature facilitates active metabolism w/o need of catalysis c) Enzymes have high optimal temperatures d) Enzymes are insensitive to temperature Glycolysis is a metabolic pathway that helps living things extract energy from food. From this we know that glycolysis 1. 2. 3. 4. consists of a series of chemical reactions uses a number of enzymes involves the modification of a series of substrates proceeds by means of each enzyme leaving a succeeding reaction to a different enzyme 5. all of the above