Chapter 8 - Cells and Energy, Biology 196
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| 646965552 | Potential Energy | The energy of state or position. Stored energy. Stored as: chemical bonds, concentration gradient, electric charge imbalance. | |
| 646965553 | Kinetic Energy | Energy of movement. Does work, makes things change. | |
| 646965554 | Metabolism | Totality of continuously occurring chemical reactions in any living organism. | |
| 646965555 | Anabolic Reactions (Anabolism) | Link simple molecules to form complex molecules. E.g: Synthesis of a protein from amino acids. Require input of energy and capture it in chemical bonds formed. | |
| 646965556 | Catabolic Reactions (Catabolism) | *Think of catastrophe. Break down complex molecules into simpler ones and release the energy stored in chemical bonds. E.g: Polysaccharide starch is hydrolyzed into simpler ones and release the energy stored in chemical bonds. | |
| 646965557 | First law of thermodynamics | Energy is neither created nor destroyed during any conversion of energy. | |
| 646965558 | Second law of thermodynamics | When energy is converted, some of that energy becomes unavailable for work. | |
| 646965559 | Entropy | A measure of the disorder in a system. | |
| 646965560 | Enthalpy (H) | Total energy in a biological system. | |
| 646965561 | Free energy (G) | Usable energy that can do work. Cells need it for growth, cell division and maintenance. | |
| 646965562 | Entropy (S) | Unusable energy (multiplied by the absolute temperature) | |
| 646965563 | Release/Consume Free Energy Equation | ΔG=ΔH-TΔS If ΔG is negative (ΔG < 0), free energy is released. If ΔG is positive (ΔG > 0), free energy is required. (consumed) | |
| 646965564 | Disorder tends to increase | Chemical changes, physical changes, and biological processes all tend to increase entropy. | |
| 646965565 | Exergonic Reactions | Reactions that release free energy (⁻ΔG). complex molecules→ free energy + small molecules | |
| 646965566 | Endergonic Reactions | Reactions that require or consume free energy. (⁺ΔG) free energy= small molecules→ complex molecules | |
| 646965567 | Chemical Equilibrium | Balance between forward and reverse reactions. State of no net change. | |
| 646965568 | Change in free energy. | The further toward completion the point of equilibrium lies, the more free energy is released. | |
| 646965569 | ATP | Capture and transfer of free energy needed to do chemical work. A nucleotide that can be converted into a building block for nucleic acids. Releases a large amount of energy when hydrolyzed to ADP. | |
| 646965570 | ATP Structure | Composed of a nitrogenous base adenine, bonded to a sugar ribose, attached to a sequence of three phosphate groups. | |
| 646965571 | Characteristics of ATP account for free energy release | 1. Free energy of P-O bond between phosphate groups is higher than energy of the O-H bonds that form after hydrolysis. 2. Phosphate groups are negatively charged, takes energy to get phosphates near each other to make the covalent bond that links them together. | |
| 646965572 | Bioluminescence | The production of light by living organisms. It is an endergonic reaction driven by ATP hydrolysis. | |
| 646965573 | Energy Coupling Cycle | ADP picks up energy from exergonic reactions to become ATP, which then donates energy to endergonic reactions. | |
| 646965574 | Catalysts | Substances that speed up reactions without themselves being permanently altered. Most are called enzymes. Earliest ones are rybozymes. | |
| 646965575 | Energy Barrier | Exergonic reactions proceed only after the reactants are pushed over the energy barrier by some added energy. | |
| 646965576 | Activation Energy | Amount of energy needed to start the reaction. | |
| 646965577 | Transition State Intermediates | In chemical reaction, the Activation energy is the energy needed to change the reactants into unstable molecular forms called transition state intermediates. Higher free energies than the reactants or the products. | |
| 646965578 | Activation energy come from? | If system is heated all the reactant molecules move faster and have more kinetic energy. Reaction would speed up. Would not work in living systems, would accelerate all reactions including denaturation. Instead living systems lower the energy barrier by bringing the reactants close together. | |
| 646965579 | Enzymes bind specific reactants at specific sites | Usually recognizes and binds to only one or few closely related reactants and catalyzes only a single chemical reaction. | |
| 646965580 | Substrate | Bind to a particular site on the enzyme, active site, where catalysis takes place. specifity of an enzyme has to do with its shape, functional group and properties. | |
| 646965581 | Enzyme Substrate Complex | Binding of a substrate to the active site held together by a hydrogen bond, temporary covalent bond or electrical attraction. Gives rise to product and free enzyme. | |
| 646965582 | Free enzyme | Same chemical form at end of reaction than at the beginning. | |
| 646965583 | Enzymes orient substrates | Part of the activation energy is used to bring together specific atoms so that bonds can form. | |
| 646965584 | Enzymes can induce strain in the substrate | Enzyme can cause bonds in the substrate to stretch putting it in an unstable transition state. Rendering bonds unstable and more reactive. | |
| 646965585 | Enzymes can temporarily add chemical groups to substrates | Side chains (R groups) of an enzyme's amino acids make its substrates more chemically reactive. | |
| 646965586 | Acid Base Catalysis | Transfer H⁺ to or from the substrate destabilizing a covalent bond and allowing it to break. | |
| 646965587 | Covalent Catalysis | Functional group in the side chain froms a temporary covalent bond from with portion of the substrate. | |
| 646965588 | Metal Ion Catalysis | Copper, Iron and Manganese. Can gain or lose electrons without detaching from enzymes. Important in oxidation-reduction reactions. | |
| 646965589 | Enzyme | Typically a protein containing hundreds of amino acids and a single folded polypeptide chain or of several subunits. Substrate generally a small molecule or small part of a large molecule. Active site usually 6-12 amino acids. | |
| 646965590 | Active site is specific to substrate | Binding of the substrate to the active site depends on the same kind of forces that mantain tertiary structure of enzyme. Hydrogen bonds, Electrically charged groups, and Hydrophobic Interactions. Enzyme=substrate; Lock=key | |
| 646965591 | Enzyme changes shape when it binds a substrate | Induced fit: Shape changes expose the active site of the enzyme. Explains why enzymes are so large. -Provides a framework for amino acids to be properly positioned in relation to the substrate. -Significant changes in protein shape &structure. -Provides binding sites for regulatory molecules. | |
| 646965592 | Prosthetic Groups | Non amino acid atoms or molecular grouping permanently bound to their enzymes. E.g: Flavin nucleotide - cellular respiration | |
| 646965593 | Cofactors | Inorganic ions that bind to certain enzymes. Iron, Copper, Zinc. | |
| 646965594 | Coenzyme | Carbon containing molecule required for the action of one or more enzymes. Coenzyme = substrate in that it doesn't bind permanently to the enzyme. ATP &ADP can be considered coenzymes; they are substrates. In animals - coenzymes are vitamins, not synthesized by the body. | |
| 646965595 | Substrate Concentration Affects Reaction Rate | The higher the concentration of the substrate, the more reactions per unit of time. Also changes the shape of a plot of rate versus substrate concentration. Initially increases until max rate has been reached. | |
| 646965596 | Saturation phenomenon | Like facilitated diffusion. Nothing is gained by adding more substrate, no free enzyme molecules are left to act as catalysts. | |
| 646965597 | Maximum Rate of Catalyzed Reaction | Can be used to measure effectiveness of an enzyme. (Turnover Number) Ranges from 1 molecule/2 sec to 40 million molecules/ sec. | |
| 646965598 | Enzymes regulated by Inhibitors | Natural inhibitors regulate metabolism. Artificial ones - treat disease, kill pests, how enzymes work. | |
| 646965599 | Irreversible Inhibition | ... |
