collective term for thousands of biochemical reactions
that occur in a living cell
Metabolic Pathways
a series of enzyme controlled reactions
can be reversible/irriversible
Anabolic reactions
large molecules are synthesised from
several smaller molecules - energy
required
Catabolic reactions
Large molecules are broken down into
smaller molecules - energy released
Control of Metabolic Pathways
Gene Expression - genes are switched on and off. inducer binds to
repressor, enzyme activity switched on, when all substrates synthesied,
inducer frees repressor and repressor then switches off gene
Signal Molecules - can trigger reactions that switch genes
on/off. Inracellular signal molecules work inside the cell that
produced them, Intercellular signal molecules is from outside
the cell that produced them.
Inhibitors
Non-Competitive
Bind to non-active sight and alter the
shape of the active site, permanently
denaturing enzyme
Effect is permanent
Competitive
Similar shape to enzyme active
site, bind to it, and temporarily
block it from binding with substrate
Effect can be cancelled out
by and increase in substrate
concentration
End Product (negative feedback) inhibition
the end product acts as a negative feedback to
the pathway. inhibits and earlier enzyme, stops
wasteful conversions
Enzymes
Biological catalysts, speed up reaction by lowering
activation energy and providing and alternative route,
without being used up
Activation energy is the minimum energy required for bonds to break and
a reaction to take place, enzymes lower this so it can take place in living
cells, below 40.C
induced fit
each enzyme can only act on one substrate. the active site is
flexible and can fit perfectly to the substrate