Rebecca DavenportBIOL 1406 BW110/10/16Ch 8 blue print- Energy and Metabolism1. Metabolism- the totality of an organism chemical reactionsa. A metabolic pathway begins with a specific molecule and ends with a product.i. Multistep process- series of reactions to get desired product.b. Each step is catalyzed by a specific name.c.d. Metabolism= Catabolism + Anabolismi. Anabolic pathways consume energy to build complex molecules from simpler ones.1. Requires energy2. Ex: Synthesis of proteins from amino acidsii. Catabolic pathways release energy by breaking down complex molecules into simpler compounds1. Bonds break and form, which releases energy and forms lower-energy breakdown products2. Ex: Breaking down starch into glucose molecules2. Energy- ability to promote change or do work.a. 2 forms:i. Kinetic- associated with movement1. Thermal energy is kinetic energy associated with random movement of atoms or moleculesa. Does not contribute to work (not useful)ii. Potential- due to structure or location1. Chemical energy is energy stored in molecular bonds.b. 2 laws of Thermodynamics:i. First law-1. Law of conservation of energy2. Energy cannot be created or destroyed BUT3. Can be transformed from one type to anotherii. Second law-1. Transfer or transformation of energy from one form to another increasesentropy.2. Entropy- is a measure of disorder (S)3. During every energy transfer or transformation, some energy is unusable, and is often lost as heat.c. Free energy: the energy available to do work (useful)1. denoted by the symbol G (Gibb’s free energy)ii. Measure of a system’s instability1. Unstable system has a higher G and higher energy2. More stable system has a lower G and lower energy3. Systems want to move towards greater stabilityiii. Key factor is the free energy change1. ΔG =Gfinal – Ginitial2. A negative number tells us we lost energy aka more stable.3. Postive number means we gained energy aka less stable.iv. Spontaneous and Nonspontaneous Reactions1. Spontaneous or Exergonic: Energetically favorable aka wants to happen.a. ΔG<0 or negative free energy change (-ΔG)b. No input of energyc. Not necessarily fastd. Release energy2. Not spontaneous or Endergonic: energetically unfavorable a. ΔG>0 or positive free energy change (+ΔG)b. Requires addition of free energyc. Needs energy3.d. ATP: Adenosine triphosphate (Adenine + ribose + 3 phosphate (the 3 phos. All have negative charges, which don’t like to be so close, so when you cut one off it springs awayreleasing energy aka ATP hydrolysis))i. Energy is releasedii. Energy that can drive a variety of cellular processes.iii. ΔG = -7.3 kcal/moleiv. ATP Hydrolysis- 1. Energy coupling: An endergonic reaction can be coupled to an exergonic reaction (endergonic reaction drives exergonic reaction)2. Both reactions as a “couple” will be spontaneous if net free energy change for both processes together negative3. ATP drives endergonic reactions by phosphorylation:a. transferring a phosphate group to some other moleculeb. The recipient molecule is called a phosphorylated intermediateTransition stateActivation energy4.e. Activation Energy: Initial input of energy required to start reaction.i. For a reaction to occur, need to contort reactant into an unstable form1. Requires energy from surroundings – normally heatii. Transition State: unstable condition where bonds are able to breakiii. This can be a very slow process….3. Enzymes- proteins that act as a catalyst.a. What’s the purpose of an enzyme? To speed up a reaction.b. Decrease activation energy for reactionsc. Conformation affected by environmental conditionsi. Temp, pH can affect folding/activity.1. If it’s not folded it’s not functionald.e. Enzyme features:i. Active site- location where reaction takes place.ii. Substrate- reactants that bind to active site for the reaction to occur.iii. Enzyme- substrate complex formed when enzyme and substrate bind. 1. Induced fit- binding initiates the enzyme to change shape slightly so the substrate does not fall out before reaction is complete.iv.f. Factors effecting enzymes:i. Environmental conditions (temperature, pH, chemicals)ii. Inhibitors - decrease enzymatic activity1. May be competitive or noncompetitivea. Ex: toxins, poisons, pesticides, and antibiotics2. Competitive Inhibition-a. Molecule binds to active siteb. Inhibits ability of substrate to bindc.3. Noncompetitive inhibition- binds to allosteric site and warps the active site so the substrate cannot pair with enzyme.a. Allosteric Inhibition: inhibitor binds to allosteric site- not active site.i. Allosteric regulation of enzymes- may either inhibit or stimulate an enzyme activity.1. Occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site.2. Many enzymes have active and inactive formsa. The binding of an activator stabilizes theactive form of the enzymeb. The binding of an inhibitor stabilizes theinactive form of the enzyme3.4. Feedback inhibition: the end product of a metabolic pathway shuts down the pathway.a. Prevents a cell from wasting chemical resources by synthesizing more product than is needed. b.iii. Activators- enhance ability of enzyme to catalyze a
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