Chapter 8 Introduction to metabolism Flashcards
Bioenergetics
(1) The overall flow and trans- formation of energy in an organism. (2) The study of how energy flows through organisms
kinetic energy
The energy associated with the relative motion of objects. moving matter can perform work by imparting motion to other matter
Thermal energy
Kinetic energy due to the random motion of atoms and molecules; energy in its most random form
Heat
Thermal energy in transfer from one body of matter to another
Potential energy
The energy that matter possesses as a result of its location or spatial arrangement (structure)
Chemical energy
Energy available in molecules for release in a chemical reaction; a form of potential energy
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
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
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).
Catabolic pathway
A metabolic pathway that releases energy by breaking down complex molecules to simpler molecules
Anabolic pathway
A metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules
Thermodynamics
The study of energy transformations that occur in a collection of matter
First law of Thermodynamics
The principle of conservation of energy: Energy can be transferred and transformed, but it cannot be created or destroyed
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
Entropy
A measure of molecular disorder, or randomness
Spontaneous process
A process that occurs without an overall input of energy; a process that is energetically favorable
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
Exergonic reaction
A spontaneous chemical reaction in which there is a net release of free energy
Endergonic reaction
A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings
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
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.
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
Catalysis
A process by which a chemical agent called a catalyst selectively increases the rate of a reaction without being consumed by the reaction
Energy coupling
In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction
Activation energy
Theamountofenergy that reactants must absorb before a chemical reaction will start; also called free energy of activation
Catalyst
A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction
Substrate
The reactant on which an enzyme works
Enzyme-substrate complex
A temporary complex formed when an enzyme binds to its substrate molecule(s)
Active site
The specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs
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
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
Coenzyme
An organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions
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
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
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
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
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
