Metabolic Pathways Overview
Metabolic pathways are integrated and controlled sequences of enzyme-catalyzed reactions within a cell. These pathways are crucial for maintaining cellular functions and can be either anabolic or catabolic in nature.
Definition: A metabolic pathway is a series of chemical reactions occurring within a cell, catalyzed by enzymes, to maintain life.
The structure of metabolic pathways includes:
- Reversible steps: Some reactions can proceed in both directions.
- Irreversible steps: Reactions that only occur in one direction.
- Alternative routes: Different pathways to achieve the same end product.
Example: In a typical pathway, Enzyme A catalyzes the conversion of a substrate to Intermediate 1, which can then be converted to Intermediate 2 by Enzyme B in a reversible step.
Anabolic pathways are processes that build up larger molecules from smaller ones, requiring energy.
Example: Protein synthesis from amino acids is an anabolic process.
Catabolic pathways, on the other hand, break down large molecules into smaller ones, releasing energy in the process.
Highlight: Understanding the 4 metabolic pathways and 5 metabolic processes in GCSE biology is crucial for grasping the fundamentals of cellular metabolism.