Midterm II -- Ch. 8 - Metabolism Flashcards
Metabolism
The totality of an organism’s chemical reactions.
metabolic pathway
a series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule (catabolic pathway).
catabolic pathways
metabolic pathways that release energy by breaking down complex molecules to simpler compounds
anabolic pathways
consume energy to build complicated molecules from simpler ones; aka biosynthetic pathways.
kinetic energy
energy that can be associated with the relative motion of objects.
heat/thermal energy
kinetic energy associated w/ the random movement of molecules or atoms.
potential energy
energy that is not kinetic; energy that matter posses b/c of its location or structure.
chemical energy
potential energy available for release in a chemical reaction.
thermodynamics
the study of energy transformations that occur in a collection of matter.
first law of thermodynamics
the energy of the universe is constant; Energy can be transferred and transformed, but it cannot be created or destroyed.”
entropy
a quantity used as a measure of disorder or randomness.
second law of thermodynamics
the more randomly arranged a collection of matter is, the greater its entropy; “every energy transfer or transformation increases the entropy of the universe.”
spontaneous process
a process that can occur w/p an input of energy.
free energy
the portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system.
know Gibbs free energy formula
exergonic reaction
“energy outward”; a spontaneous chemical reaction, in which there is a net release of free energy.
endergonic reaction
“energy inward”; a reaction that absorbs free energy from its surroundings.
energy coupling
the use of an exergonic process to drive an endergonic one.
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) w/ a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule.
enzyme
a macromolecule that catalyses/increases the rate of a reaction w/o being consumed by the reaction; most are proteins
catalyst
chemical agent that selectively increases the rate of a reaction w/o being consumed by the reaction.
activation energy
the initial investment of energy for starting a reaction; the energy required to contort the reactant molecules so the bonds can break; “free energy of activation.”
substrate
the reactant an enzyme reacts on.
enzyme-substrate complex.
formed when an enzyme binds to its substrates, (when there are two or more reactants).
active site
a restricted region of the enzyme molecule that binds to the substrate; typically a pocket or groove on the surrounding face of the enzyme where catalysis occurs.
induced fit
caused by the entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate.
cofactors
nonprotein helpers for catalytic activity.
coenzyme
a cofactor that is an organic molecule.
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.
noncompetitive inhibition
impede enzymatic reactions by binding to another part of the enzyme, NOT to the active site.
allosteric regulation
a case in which a protein’s function at one site is affected by the binding of a regulatory molecule to a separate 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 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.
