Growth and asexual reproduction

Abstract

Growth is increase in biomass. In protozoa and protophyta growth in an organism to a critical size is followed by division into independent daughter organisms. Thus growth is also growth in the number of organisms in a colony. If an inoculum of micro-organisms is placed in a culture medium and sampled at intervals the growth curve of the culture can be determined. After an initial accelerating phase the culture grows exponentially, that is one cell becomes two, becomes four, becomes eight, etc. at regular time intervals. The colony then reaches a plateau as the shortage of metabolic substrates or the accumulation of toxic waste products become limiting factors. This is usually followed by lysis and death of most of the cells, or encystment in some species.