Metabolism











Structure function
relationships

The chemical basis of life

"Cells obey the laws of chemistry." (James D. Watson, Molecular Biology of the Gene)

During the 19th century scientists thought that a "vital force" outside the laws of chemistry differentiated animate (living) from inanimate (non-living) things.

This idea began to be discredited with experiments performed early in the 19th century showing that chemicals associated with living things could be generated by chemical reactions from non-living source material.

• 1828: Wöhler converted ammonium cyanate to urea, a nitrogenous compound produced as a waste material by living things.

• 1845: Kolbe was able to synthesize acetic acid, the principal component of vinegar, starting with carbon.

Up until relatively recently, the nature of the chemicals that make up living things was still obscure. Research in the latter half of the 19th century focused on determining the nature of these compounds. During this time the understanding that it was the structure of the compounds that gave them their unique properties became clearer.

Research during the last 50 years has focused on understanding the origin of these molecules--how does the cell make the bewildering variety of chemicals necessary for growth?

Beginning around the turn of the century biochemists began to decipher the rules of cellular metabolism by isolating the various chemical components of the cell and determining how they are related to each other.

During growth, cells transform food materials into all of the basic building blocks of the cell. This process of transforming the chemical constituents of food is called metabolism.

Much of the business of cells involves processing various molecules through elaborate pathways. Molecules called enzymes cause the changes that occur in these pathways. Enzymes promote the chemical reactions necessary for the transformations but remaining unchanged themselves. As we will see, nearly all of the enzymes in a cell are members of the special class of compounds called proteins.

Along with an understanding of the inter-relationships among these chemicals, biochemists increasingly began to understand their structures, and how those structures related to their functions.