Metabolism Flashcards
(35 cards)
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.
bioenergetics
(1) The overall flow and transformation 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. See also heat.
heat
The total amount of kinetic energy due to the random motion of atoms or molecules
in a body of matter; also called thermal energy. Heat is energy in its most random
form.
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
thermodynamics
The study of energy transformations that occur in a collection
of matter. See first law of thermodynamics; second law of thermodynamics.
first law of thermodynamics
The principle of conservation of energy: Energy can be transferred and transformed,
but it cannot be created or destroyed
entropy
A measure of disorder, or randomness
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.
spontaneous process
A process that occurs without an overall input of energy; a process that is
energetically favourable.
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 Δ(ΔG) is calculated by the equation ΔG = ΔH − TΔS, where ΔH is
the change in enthalpy (in biological systems, equivalent to total energy), T is the
absolute temperature, and ΔS is the change in entropy
exergonic reaction
A spontaneous chemical reaction, in which there is a net release of
free energy.
endergonic reaction
A nonspontaneous chemical reaction, in which free energy is
absorbed from the surroundings.
energy coupling
In cellular metabolism, the use of energy released from an exergonic reaction to
drive an endergonic reaction.
ATP (adenosine triphosphate)
An 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.
catalyst
A chemical agent that selectively increases the rate of a reaction without
being consumed by the reaction.
activation energy
The amount of energy that reactants must absorb before a chemical reaction will
start; also called free energy of activation.
