Biochemistry and metabolism

Principles of Human Physiology

Biochemistry and metabolism of cells

While all physiology can be explained by the functioning of cells, the functioning of cells can be explained by the biochemistry and metabolism they carry out. In other words, cells use chemical reactions and molecular interactions to function. They are what some people call nanotechnology based machines. Here we do not want to use the machine analogy because it is misleading in many ways. While cells carry out processes like machines, cells are made and operate very differently. The employ networks of chemical reactions - called metabolic pathways - that are continuously running and cannot be switched off, hence the need for energy supply in form of food. Metabolic pathways are integrated with each other, and are also integrated with signal transduction pathways that trigger internal changes due to external and internal signals.

To access the interactive metabolic pathway map shown below click here: KEGG.
KEGG metabolic pathway map

Biochemistry borrows its methodology from chemistry and the great achievement of understanding pathways has started with the ability of organic chemists in the 1930s to isolate individual enzymes and study each step of a pathway one at a time. Eventually, full pathways have been reconstituted in vitro using only purified and/or synthetic components.

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