ENZYMES
(a) The role of enzymes in catalysing reactions that affect metabolism at a cellular and
whole organism level
● To include the idea that enzymes affect both structure and function.
Most of the processes necessary to life involve chemical reaction, and these
reactions need to happen at a high rate to fulfill our metabolic need. This would
require great pressures and temperatures that the body cannot maintain or withstand.
Therefore, enzymes, biological catalysts, are needed because living organisms need
to be built and maintained and this involves the synthesis of large polymer-based
compounds. For example, cellulose forms walls of plant cells and long proteins form
the contractile filaments of muscles in animals. Different cell components are
synthesized by anabolic reactions, catalysed by enzymes, and assembled into cells,
which then forms the tissues, organs and is essential for the structure and function of
the whole organism.
Energy is constantly required for the continuation of the majority of living processes
and is released from large organic molecules, such as glucose, and these are
obtained by the digestion of even larger organic molecules, polymers, such as starch.
The digestion of such molecules and is catalysed by enzymes and enzymes also
control the metabolic pathways, consisting of catabolic reactions, in breaking down
organic molecules.
Metabolism is the sum of all of the different reactions and reaction pathways
happening in a cell or in an organism, and it can only happen as a result of enzymes,
including the anabolic reactions that are essential for structure, and of molecules that
facilitate function, including enzymes themselves, proteins and storage molecules
and the catabolic reactions that release energy for the continued function, of all active
processes and in breaking down toxins.
(b) The role of enzymes in catalysing both intracellular and extracellular reactions
● To include catalase as an example of an enzyme that catalyses intracellular
reactions and amylase and trypsin as examples of enzymes that catalyse
extracellular reactions.
Intracellular enzymes
In any cell, and within its organelles, there may be up to 1000 different metabolic
reactions going on at the same time, each catalysed by a different enzyme and some
of these are part of a metabolic pathway. Each metabolic pathway in a living cell is
one of a series of consecutive reactions, every step catalysed by a specific enzyme
that produces a specific product. The various reactants and intermediates act as
substrates, and are called metabolites. The metabolites, may be broken down, in
catabolic reactions, requiring energy, or be involved in the synthesis of larger
molecules, in anabolic processes, that require energy. Examples of complex
metabolic pathways are photosynthesis and respiration.
(a) The role of enzymes in catalysing reactions that affect metabolism at a cellular and
whole organism level
● To include the idea that enzymes affect both structure and function.
Most of the processes necessary to life involve chemical reaction, and these
reactions need to happen at a high rate to fulfill our metabolic need. This would
require great pressures and temperatures that the body cannot maintain or withstand.
Therefore, enzymes, biological catalysts, are needed because living organisms need
to be built and maintained and this involves the synthesis of large polymer-based
compounds. For example, cellulose forms walls of plant cells and long proteins form
the contractile filaments of muscles in animals. Different cell components are
synthesized by anabolic reactions, catalysed by enzymes, and assembled into cells,
which then forms the tissues, organs and is essential for the structure and function of
the whole organism.
Energy is constantly required for the continuation of the majority of living processes
and is released from large organic molecules, such as glucose, and these are
obtained by the digestion of even larger organic molecules, polymers, such as starch.
The digestion of such molecules and is catalysed by enzymes and enzymes also
control the metabolic pathways, consisting of catabolic reactions, in breaking down
organic molecules.
Metabolism is the sum of all of the different reactions and reaction pathways
happening in a cell or in an organism, and it can only happen as a result of enzymes,
including the anabolic reactions that are essential for structure, and of molecules that
facilitate function, including enzymes themselves, proteins and storage molecules
and the catabolic reactions that release energy for the continued function, of all active
processes and in breaking down toxins.
(b) The role of enzymes in catalysing both intracellular and extracellular reactions
● To include catalase as an example of an enzyme that catalyses intracellular
reactions and amylase and trypsin as examples of enzymes that catalyse
extracellular reactions.
Intracellular enzymes
In any cell, and within its organelles, there may be up to 1000 different metabolic
reactions going on at the same time, each catalysed by a different enzyme and some
of these are part of a metabolic pathway. Each metabolic pathway in a living cell is
one of a series of consecutive reactions, every step catalysed by a specific enzyme
that produces a specific product. The various reactants and intermediates act as
substrates, and are called metabolites. The metabolites, may be broken down, in
catabolic reactions, requiring energy, or be involved in the synthesis of larger
molecules, in anabolic processes, that require energy. Examples of complex
metabolic pathways are photosynthesis and respiration.
