Flagellar Growth

Abstract

The flagellum is the tail-like locomotive organelle of the cell. Both complex and bacterial flagella grow by the polymerization of protein precursors at the distal tip of their flagellar fibers; that is they grow from the end furthest removed from the cell body (Rosenbaum and Child, 1967, Tamm, 1967, Iino, 1969). Generally the rate of flagellar growth is fastest initially and decreases continuously until growth stops at a species specific length. If a flagellum is broken, it will regenerate. The kinetics of regenerative growth parallel those of normal growth with the initial rate of elongation being a decreasing function of the stump length (figure 1). Both the physical process and kinetics of elongation thus suggest that the growth rate and final length of the flagellum are controlled by a decreasing concentration of a polymerization participant at the building site. In this paper a model based on this hypothesis is discussed.