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Flashcards in Chapter 8 Introduction to metabolism Deck (37):
1

Bioenergetics

(1) The overall flow and trans- formation of energy in an organism. (2) The study of how energy flows through organisms

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kinetic energy

The energy associated with the relative motion of objects. moving matter can perform work by imparting motion to other matter

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Thermal energy

Kinetic energy due to the random motion of atoms and molecules; energy in its most random form

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Heat

Thermal energy in transfer from one body of matter to another

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Potential energy

The energy that matter possesses as a result of its location or spatial arrangement (structure)

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Chemical energy

Energy available in molecules for release in a chemical reaction; a form of potential energy

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Metabolism

The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism

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Metabolism

The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism

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Metabolic pathway

A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule to simpler molecules (catabolic pathway).

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Catabolic pathway

A metabolic pathway that releases energy by breaking down complex molecules to simpler molecules

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Anabolic pathway

A metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules

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Thermodynamics

The study of energy transformations that occur in a collection of matter

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First law of Thermodynamics

The principle of conservation of energy: Energy can be transferred and transformed, but it cannot be created or destroyed

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Second law of Thermodynamics

The principle stating that every energy transfer or transformation increases the entropy of the universe. Usable forms of energy are at least partly converted to heat

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Entropy

A measure of molecular disorder, or randomness

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Spontaneous process

A process that occurs without an overall input of energy; a process that is energetically favorable

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Free energy

The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system. The change in free energy of a system (∆G) is calculated by the equation ∆G = ∆H - T∆S, where ∆H is the change in enthalpy (in biological systems, equivalent to total energy), ∆T is the absolute temperature, and ∆S is the change in entropy

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Exergonic reaction

A spontaneous chemical reaction in which there is a net release of free energy

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Endergonic reaction

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings

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ATP (adenosine tri-phospahte)

n adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells

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Phosphorylated intermediate

A molecule (often a reactant) with
a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule.

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Enzyme

A macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. Most enzymes are proteins

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Catalysis

A process by which a chemical agent called a catalyst selectively increases the rate of a reaction without being consumed by the reaction

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Energy coupling

In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction

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Activation energy

Theamountofenergy that reactants must absorb before a chemical reaction will start; also called free energy of activation

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Catalyst

A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction

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Substrate

The reactant on which an enzyme works

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Enzyme-substrate complex

A temporary complex formed when an enzyme binds to its substrate molecule(s)

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Active site

The specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs

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Induced fit

Caused by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate

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Cofactor

Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or may bind loosely and reversibly, along with the substrate, during catalysis

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Coenzyme

An organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions

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Competitive inhibitors

A substance that reduces the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics

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non-competitive inhibitors

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme’s shape so that the active site no longer effectively catalyzes the conversion of substrate to product

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Allosteric regulation

The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site

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Cooperativity

A kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the other subunits, facilitating binding of additional substrate molecules to those subunits

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Feedback inhibition

A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway