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Introduction to Metabolism Metabolism: Energy and Life __________________________ = totality of an organism’s chemical processes Organized into pathways that are ordered series of _____________________ controlled reactions. _____________________ pathways = release energy by breaking down complex molecules into simpler compounds _____________________ pathways = use energy to build complicated molecules from simpler compounds. Energy = ________________________________________________ Exists in many different forms (thermal, electrical, mechanical, etc.) ______________________ energy = energy in the process of doing work ______________________energy = energy that could do work can be transformed from one form to another (follows laws of thermodynamics) ex. Kinetic energy of sunlight is transformed into potential energy of chemical bonds during photosynthesis ex. Potential energy in chemical bonds of ATP is transformed into kinetic energy that can drive biological processes. Laws of Thermodynamics & Entropy All energy changes are subject to two laws of thermodynamics: 1. «1ST Law » = ________________________________________________________________ ____________________________________________________________________________ 2. « 2nd Law » = ________________________________________________________________ ____________________________________________________________________________ ___________________ = quantitative measure of __________________ that is proportional to randomness (designated by the letter `S`) ________________ systems = collection of matter under study which is isolated from its surroundings. ________________ system = system in which energy can be transferred between the system and its surroundings. The _________________ of a system may decrease, but the entropy of the system plus its surrounding must always ________________. Highly ordered living organisms do not violet the 2nd law because they are always open systems. For example, animals; o o o Thus, combining the 1st and 2nd law of thermodynamics: o The ____________________ of the energy in the universe is constanct, but it ________________________is not! Organisms live at the Expense of Free Energy ___________________________ = the system’s energy that is available to do work. o Is related to the system’s total energy, _____________________ and its ____________________ in the following way: Where: G = H - TS Since, the maximum amount of usable energy that can be harvested from a particular reaction is the system’s free energy change: Helmholtz equation (at constant temperature and pressure) G = H - TS where: Significance of Gibbs free energy: o Indicates the maximum amount of a system’s energy is available to do work o Indicates whether a reaction will occur spontaneously (reaction will occur without a further input of energy) or not. How? During a chemical reaction, _____________ molecules must _____________ energy for their bonds to _______________, but energy is __________________ when bonds ______________ between the rearranged atoms of the products. Consequently, reactions have a net energy _____________ or ______________. In a spontaneous reaction, G of a system _________________ (___________________) Gibbs free energy is being released and the reaction is said to be_______________ An ______________________________________ is not spontaneous and is accompanied by an ________________in G (_______________________________) Gibbs free energy is required to drive the reaction. Metabolic Disequilibrium Since metabolic reactions are reversible, they have the potential to reach equilibrium. o At equilibrium ___________, so the system can ___________________________ o Maintaining disequilibrium is essential for life. o In the cell, these potentially reversible reactions are __________________________ away from equilibrium, because the products of some reaction become the reactants fro the next reaction in the metabolic pathway. ATP Powers Cellular Work ATP powers cellular work by coupling ______________________ and ___________________ reactions by acting as an intermediate between them ATP (________________________________) = nucleotide with unstable phosphate bonds. ATP consists of: ____________________________ between phosphate groups can be _________________ in an exergonic reaction (releases energy) The _____________________________________ of ATP is coupled with ________________ (energy requiring) reactions by transferring a phosphate group, and its 7.3 kcal/mol of energy to another molecule Ex. Glutamic acid + NH3 gluatmine G= +3.4 kcal/mol Glu + NH3 Glu-P Enzymes Enzymes ____________________ metabolic reactions by ________________ energy barriers in order to speed up the rate of the reaction. Thus, enzymes acts as biological _________________________ = chemical agent that increases the rate of reaction without being changed in the process Before any reaction can occur, the reactants must absorb energy to break chemical bonds. This initial energy investment is the ___________________________________. effect of catalyst on effect of catalyst on exergonic reactions endogonic reactions ___________________________ = unstable condition of reactant molecules t hat have absorbed sufficient energy to react.