Ecological Physiology: Other Aspects

Abstract

Between two divisions, a cell will pass through a number of temporally more or less well-defined phases characterized by DNA synthesis, various morphogenetic events, protein synthesis, and growth. During balanced growth the temporal succession of these events is well defined relative to the time of cell division. However, in many protozoa, at least during constant environmental conditions, the phenotype remains fairly constant except for changes in cell size and, of course, except during cell division. In some species, however, the phenotypic appearance may change considerably, either as an obligatory part of the life cycle, or as a result of environmental changes. Cases in which sexuality is involved will be discussed in Section 5.2.