Energy and Metabolism

Transcription

1 and Metabolism KEY WORDS: Free ( G) Potential energy Kinetic energy Enzyme Substrate Activation energy Exergonic reaction Endergonic reaction Catalyst ATP/ ADP 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. Chemical Stored in chemical bonds -high energy electrons Some molecules store a lot of energy 1. Fire; a piece of wood 2. A loaded gun; a flying bullet 3. A rock on top of a hill; a rock rolling down the hill 4. None of these are correct. 5. All of these are correct. Some molecules store much less Carbos, lipids Carbon dioxide, water Chemical can be transferred/transformed Sugar + oxygen carbon dioxide + water C 6 H 12 O 6 + O 2 + heat CO 2 + H 2 O + First Law of Thermodynamics: : neither created nor destroyed Converted from one form to another Exchanged between substances

2 Second Law of Thermodynamics: All exchanges of energy increase the entropy of the universe Two laws of thermodynamics Entropy: Disorder or randomness of a system Heat is most disorganized form of energy Reactions that entropy happen spontaneously & release energy Transformed Exergonic Reactions Release energy Spontaneous Usually breakdown of complex molecules Endergonic Reactions Usually involve synthesis of complex molecules Not Spontaneous 6CO 2 + 6H 2 O + C 6 H 12 O 6 + 6O 2 Question: Which of the following reactions is endergonic? 1. CO 2 and H 2 O Glucose 2. Amino acids Proteins 3. Triglycerides Fatty acids 4. Ions moving across membrane from an area of high concentration to an area of low concentration. Require energy

3 Question: Coupled Reactions Exergonic provides energy for the endergonic Which of the following reactions releases energy? 4. Ions moving across membrane from an area of high concentration to an area of low concentration. Exergonic glucose CO 2 + H 2 O Endergonic Amino acids Protein Living organisms Metabolism All chemical reactions in an organism Living organisms Capture energy to drive chemical reactions. Convert raw energy into usable form Sunlight, food ATP Anabolism Catabolism The structure and hydrolysis of ATP ATP: the Cell s Rechargeable Battery ATP energy charged battery ADP dead battery This energy can then be used to run an energy requiring reaction.

4 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. Some energy is lost, but other energy is created. 2. Some energy must come from the sun. 3. Some energy is transformed into heat. 4. is gained for future use. 5. Some energy is permanently and completely destroyed. ATP stores energy in the form of 1. mechanical energy 2. heat 3. complex carbohydrates 4. chemical bond energy 5. amino acids The complexity of metabolism Equation: Gibb s Free G = H T S available for work All energy NOT available for work

5 The relationship of free energy to stability, work capacity, and spontaneous change changes in exergonic and endergonic reactions profile of an exergonic reaction Disequilibrium and work in closed and open systems Is G for an exergonic reaction positive or negative? What is the difference between: Anabolism Catabolism Metabolism

6 From an energy perspective, when is equilibrium reached? KEY WORDS: Enzyme Activation energy Catalyst Substrate Active site Induced fit Coenzyme Allosteric site Competitive inhibitor Noncompetitive inhibitor Feedback inhibition Enzymes Enzymes and Shape Activation Activation Active Site Net Released Induced fit: Handshake between substrate and enzyme 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 + H 2 O glucose + fructose

7 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. lowering the temperature 2. lowering the pressure 3. using an enzyme 4. changing the amount of the reactants 5. supplying ATP Which of the following will lower the activation energy of a reaction in a cell? Enzymes 1. lowering the temperature 2. lowering the pressure 3. using an enzyme 4. changing the amount of the reactants 5. supplying ATP 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

8 4 Things that Affect Enzyme Activity 1. Substrate concentration 2. Enzyme concentration Environmental factors affecting enzyme activity 3. ph 4. Temperature Shape of enzyme (Protein denatured) Inhibition of enzyme activity Enzyme Regulation Enzymes can be turned on and off Regulated by other molecules in the cell Examples: Allosteric regulation Feedback inhibition Inhibitors Allosteric regulation of enzyme activity Feedback inhibition

9 If an enzyme solution is saturated with substrate, the most effective way to obtain an even faster yield of products is: a) Add more enzyme b) Heat the solution c) Add more substrate d) Add an allosteric inhibitor e) 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. consists of a series of chemical reactions 2. uses a number of enzymes 3. involves the modification of a series of substrates 4. proceeds by means of each enzyme leaving a succeeding reaction to a different enzyme 5. all of the above