Metabolic Pathways
What is metabolism?
Metabolism encompasses the integrated
and controlled pathways of enzymecatalysed reactions within a cell.
Metabolic pathways refer to reactions in
the body that are linked together.
What are the two types of enzymecatalysed reaction?
• Biosynthetic reactions (you probably
called them synthesis reactions
previously), which are also referred to as
anabolism.
• Breakdown reactions, which are also
referred to as catabolism.
Synthetic reactions
Example:
glucose-1-phosphate
phosphorylase
starch
This reaction requires the input of energy to
proceed (anabolic reaction).
Breakdown reactions
Example:
starch
amylase
maltose
This reaction releases energy (catabolic
reaction).
What else do you need to
know?
• Metabolic pathways can have reversible
and irreversible steps.
• Alternative pathways may exist that can
bypass steps in a pathway.