Metabolic Pathway: In biochemistry, a metabolic pathway is a series of chemical reactions occurring within a cell, catalyzed by enzymes, resulting in either the formation of a metabolic product to be used or stored by the cell, or the initiation of another metabolic pathway (then called a flux generating step).
Many pathways are elaborate, and involve a step by step modification of the initial substance to shape it into the product with the exact chemical structure desired.
Various metabolic pathways within a cell form the cell's metabolic network. In the metabolic pathway a substrate enters depending on the needs of the cell, i.e. the specific combination of concentrations of the anabolical and catabolical end products (the energetics of the flux-generating step).
Metabolic pathways include the principal chemical, mostly enzyme-dependent, reactions that an organism needs to keep its homoeostasis.