3 - Enzymes Flashcards
how do enzymes speed up a reaction
by lowering activation energy required to initiate a given reaction
enzymes
an organic molecule (carbon based molecules)
typically a protein, that catalyses
(speeds up) specific reactions
how do enzymes function
They bind to a molecule called a substrate (the reactant), facilitating a chemical reaction that converts the substrate into a product or products. The product then leaves the enzyme, which remains unchanged and can catalyse further reactions.
enzyme-substrate complex
the structure formed when an enzyme and substrate are bound together
active site
the part of an
enzyme where the substrate binds
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
denature
the disruption of
a molecule’s structure by an external factor such as heat
- bonds that create its tertiary and quaternary structures are broken down. Denaturation causes a conformational change in the active site
optimum
the point at which for a
given condition (e.g. temperature),
the maximum function of an enzyme occurs
how does substrate concentration effect rate of reaction
lower substrate concentration
lower reaction rate and vice versa till saturation point
limiting factor
a factor that
prevents the rate of reaction from
increasing
enzyme inhibitors are
molecules that bind to an enzyme and prevent it from performing
its function.
When an inhibitor is bound to an enzyme, the enzyme can either no longer
catalyse its specific reaction, or its functioning is greatly reduced.
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
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 pathways
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
what occurs in co-enzyme cycling
enzyme remains unchanged
- During the reaction,
the coenzyme binds to the active site, donates energy or molecules
- cannot be
immediately reused
- After the reaction
- the coenzyme leaves the enzyme and is recycled
by accepting more energy, so it can then go on to assist in more reactions.
ATP
adenosine triphosphate,
a high energy molecule that, when broken down, provides energy for
cellular processes
ADP
adenosine diphosphate,
the unloaded form of ATP
The conversion of ADP to ATP is a ____
reaction, whilst ATP turns into ADP via a ______ reaction.
phosphorylation (adding phosphate)
dephosphorylation
(removing phosphate)
differences between the secondary and tertiary levels of structure in a functional enzyme.
secondary level -determined by hydrogen bonds, and is the folding and coiling of a section of the polypeptide chain alpha helices and beta-pleated sheets.
enzyme takes on a three-dimensional globular shape, it is said to have tertiary structure
