Metabolites and Their Types
What Are Metabolites?
Metabolites are small molecules involved in metabolism, essential for energy production, growth, repair, and various cellular functions.
They are intermediates or end products of metabolic pathways.
Types of Metabolites
Primary Metabolites
Involved in basic processes like growth and energy production.
Examples: Glucose, amino acids, ATP, fatty acids.
Secondary Metabolites
Non-essential for growth but important for defense, signaling, and adaptation.
Examples: Alkaloids (nicotine), terpenoids (menthol), flavonoids, antibiotics (erythromycin).
Primary Metabolism
Primary metabolism involves pathways essential for life, such as photosynthesis, respiration, and the biosynthesis of carbohydrates, amino acids, and lipids.
Key Processes:
Photosynthesis:
Converts light energy into chemical energy, forming sugars from carbon dioxide and water.
Respiration:
Breaks down sugars to release energy for cellular processes.
Biosynthetic Routes:
Carbohydrate Synthesis: Produces sugars via the Calvin Cycle.
Amino Acid Metabolism: Forms the building blocks for proteins.
Lipid Synthesis: Builds cell membranes and energy-storing molecules.
Secondary Metabolism
Secondary metabolites are derived from primary metabolic pathways and include diverse classes of compounds such as alkaloids, terpenoids, and phenolics.
Biosynthetic Origins:
Phenylpropanoids: Derived from the amino acid phenylalanine.
Terpenoids: Derived from isoprene units originating in carbohydrate metabolism.
Alkaloids: Derived from amino acids and other primary metabolic intermediates.
Determination of Metabolic Pathways
Understanding metabolic pathways requires experimental techniques that map out the biosynthesis and function of metabolites:
Key Techniques:
Biochemical Techniques:
Enzyme isolation, in vitro assays, and substrate feeding experiments to identify enzymatic steps in pathways.
Radioisotope Labeling:
Introducing radioactive isotopes (e.g., 14C or 3H) into precursors to track the movement of atoms through metabolic routes.
Analytical Methods:
Techniques like chromatography, mass spectrometry, and NMR are used to identify and quantify metabolites.
Molecular Biology Tools:
Genetic manipulation, gene expression profiling, and mutant analysis to study enzyme roles and regulatory networks.