Autotrophs versus Heterotrophs

    In the haploid bread-mold Neurospora, wild-type autotrophs are able to grow either on complete medium containing a variety of amino acids, or minimal medium containing only basic CHNOPS salts (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur). After exposure to X-rays, a series of mutant heterotrophs are obtained that are able to grow only on complete medium: something has affected their ability to synthesize amino acids. "Growth" and "No Growth" on minimal medium are alternative phenotypes.

All text material © 2007 by Steven M. Carr