Chapter 3 - Enzymes Flashcards
enzyme
an organic molecule, typically a protein, that catalyses (speeds up) specific reactions
catalyst
a substance capable of increasing the rate of a reaction without being used up
catalyse
to increase the rate of a reaction
substrate
the reactant of a reaction catalysed by an enzyme
reactant
a molecule that undergoes a transformation into a product. When enzymes are involved, the reactant is called a substrate
product
the transformed molecule created in a reaction
active site
the part of an enzyme where the substrate binds
enzyme-substrate complex
the structure formed when an enzyme and substrate are bound together
conformational change
a change in the three-dimensional shape of macromolecules such as proteins
activation energy
the energy required to initiate a reaction
collision theory
explanation of chemical reactions that states that in order to react molecules must hit one another
biochemical pathway
a series of enzyme-catalysed biochemical reactions in which the product of one reaction becomes the substrate of the next reaction. Also known as a metabolic pathway
optimal
the point at which for a given condition (e.g. temperature), the maximum function of an enzyme occurs. Also known as optimum
denature
the disruption of a molecule’s structure by an external factor such as heat
conformational change
a change in the three-dimensional shape of macromolecules such as proteins
saturation point
the point at which a substance (e.g. an enzyme) cannot receive more of another substance (e.g. a substrate)
limiting factor
a factor that
prevents the rate of reaction from
increasing
limiting reagent
a reactant that
prevents the rate of reaction from
increasing
enzyme inhibitor
a molecule that
binds to and prevents an enzyme
from functioning
competitive inhibition
the hindrance of an enzyme
by blocking the active site and
preventing the substrate
from binding
non-competitive inhibition
the hindrance of an enzyme by
binding to an allosteric site and
changing the shape of the active
site to prevent the substrate from
binding
allosteric site
a region on an
enzyme that is not the active site
reversible inhibition
enzyme inhibition that involves
weaker bonds that can be
overcome
irreversible inhibition
enzyme inhibition that involves
stronger bonds that cannot be
broken
biochemical pathway
a series of enzyme-catalysed biochemical reactions in which the product of one reaction becomes the substrate of the next reaction. Also known as a metabolic pathway
cofactor
any organic or inorganic molecule, such as a coenzyme or metal ion, that assists enzyme function
coenzyme
a non-protein organic cofactor that assists enzyme function. They release energy and are recycled during a reaction
ATP
adenosine triphosphate,
a high energy molecule that, when
broken down, provides energy for
cellular processes
ADP
adenosine diphosphate,
the unloaded form of ATP
anabolic reaction
two or more smaller molecules combine to form a larger one (i.e. building things up), uses energy
catabolic reaction
larger molecule turning into two or more smaller molecules (i.e. breaking things down), releases energy
