Notes on Metabolism

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[Metabolism is the totality of an organism's chemical reactions; an emergent property of life that arises from interaction between molecules within the orderly environment of the cell

[Catabolic pathways release energy by breaking down complex molecules to simpler compounds; cellular respiration (sugar glucose broken down to carbon dioxide and water); releases energy

[Anabolic pathways consume energy to build complicated molecules form simpler ones; synthesis of a protein from amino acids

[Energy coupling links catabolic and anabolic pathways by transferring energy that was released from the downhill reactions of catabolism to be used to drive the uphill reactions of anabolism

[Bioenergetics is the study of how organisms manage their energy resources

[Energy is the capacity to do work; rearrange a collection of matter

[Kinetic energy exists in anything that moves; light, thermal energy

[Potential energy is stored energy that matter posses because of its location or structure

[Chemical energy is a form of potential energy stored in molecules as a result of the arrangement of the atoms in those molecules

[Thermodynamics is the study of the energy transformations that occur in a collection of matter

[First law of thermodynamics/Principle of conservation of energy: Energy can be transferred and transformed, but it cannot be created or destroyed

[Second law of thermodynamics: Every energy transfer or transformation increases the entropy of the universe; transform from high to low forms; most stable, less organized

[Free energy is the portion of a system's energy that can perform work when temperature is uniform throughout the system; organisms can live only at the expense of free energy acquired from the surroundings

[Equilibrium is a state of maximum stability

[Chemical reactions are reversible; when the reactions occur at the same rate back and forth, there are no further changes in the concentration of products or reactants

[Free energy of the mixture of reactants and products decreases as a reaction proceeds towards equilibrium

[An exergonic reaction proceeds with a net release of free energy; spontaneous

[An endergonic reaction is one that absorbs free energy from its surroundings; nonspontaneous

[Exergonic and endergonic together is also linked by energy coupling

[Cellular work is powered by ATP coupling

[Phosphorylation occurs when phosphate is being given up

[ATP is regenerated when phosphate is added to ADP

[Participants in a metabolic pathway

[Substrates enter a reaction (precursor, reactants)

[Intermediates are partial products, not end products, the compound between the start and end product

[Catalysts are chemical agents that change the rate of a reaction without being consumed by the reaction

[Enzymes are proteins that speed up metabolic reactions by lowering activation energy needed for reactions to take place

[Activation energy is the energy required to break bonds in the reactant molecules

[Co-factors are non-protein enzyme helpers; carry atoms or elections (energy source)

[ATP is the main source of energy carrier

[End product is the conclusion of the pathway

[Endergonic enzymes can be reused; it recognized both reactants and products in order to catalyze reaction in both directions; both may require energy

[Enzymes connect to certain substrates

[Substrates bind with enzyme at the active site

[Denaturing occurs when the 3-dimensional shape has changed; the enzyme is no longer functional for the purpose in which you need it; caused by temperature and pH level

[Inhibitors will bind with enzymes and slow it down

[Competitive inhibitors fight for the site

[Non-competitive inhibitors binds to enzyme, not at the active site, and changes its shape

[Control of metabolism

[Allosteric sites are specific receptor sites on some parts of the enzyme molecule remote from the active site

[Allosteric regulation occurs when regulatory molecules inhibits of activates enzyme activity by bonding to the allosteric site

[A regulator of a metabolic pathway

[Complex enzymes are constructed from two or more polypeptide chains; each subunit has its own active site and allosteric sites are often located where subunits are joined; entire unit can oscillate between two states; binding of activator or inhibitor can stabilize the catalytically active or inactive

[Products of a pathway acts as an allosteric inhibitor

[Feedback inhibition is the switching off of a metabolic pathway by its end product, which acts as an inhibitor of an enzyme within the pathway; for example, the inhibition of an ATP-generating catabolic pathway by the allosteric binding of ATP to an enzyme in the pathway

[Cooperativity is when an enzyme has two or more subunits, such an interaction with one substrate molecule can trigger the same favorable conformational change in all other subunits of the enzyme