Use the following organisms of the week to help you answer t

Use the following organisms of the week to help you answer the following. You may use each organism in this section only ONCE. Each question may have more than one organism that applies, but only answer for one. Bdellovibrio bacteriovorus Caulobacter crescentus Chlamydia trachomatis Clostridium acetobutylicum Deinococcus radiodurans Which organism of the week is unusual with respect to cell division?. Describe how this organism is unusual with respect to cell division.

Solution

Answer - the unusual organism would be Chlamydia trachomatis. This is because the mechanism of cell division in this organism has not been documented in any other human bacterial pathogens. Usually, bacteria divide by binary fission that requires the protein FtsZ. Due to the absence of this protein in Chlamydia, cell division occurs by a process of polarized cell division similar to the budding process (asymmetric division) seen in yeasts. Prior to cell division, the major outer-membrane protein of Chlamydia become restricted to one pole of the cell, and via this pole, the daughter cell emerges through an asymmetric expansion of the membrane. Components of the cell division machinery accumulate at the site of polar growth prior to the initiation of asymmetric membrane expansion.

Such polarized cell division of C. trachomatis is the result of the unipolar growth and FtsZ-independent fission of this coccoid organism.