Chapter 19, Problem 35A

Summary Introduction

To analyze : 

The chemical released by starving amoeboid cells.

Introduction :

Cellular slime molds belong to the class acrasiomycetes. Their somatic phase is represented by haploid and uninucleate, amoeba-like cells known as myxamoebae. Myxamoebae lack cell walls though they possess the plasma membrane. They grow and multiply to form amoeboid cells. When the food supply is exhausted, the amoeboid cells get aggregated without any fusion to form pseudoplasmodium.

Answer to Problem 35A

The correct term is acrasin.

Explanation of Solution

The cellular smile molds undergo sexual reproduction to form zygote by the fusion of two haploid amoebae. In the presence of favorable conditions, the zygote undergoes division and form haploid amoeba. In unfavorable conditions, the amoeba-like cells aggregate without fusion in response to a chemical known as acrasin. Acrasin is released by these starving amoeba-like cells. It signals these cells to form a sluglike colony which functions as a single unit. This colony forms fruiting bodies that further release spores. The spores germinate and form amoebae like organisms and, the whole cycle repeats.

Conclusion

During unfavorable conditions, the starving amoeboid cells release a chemical known as acrasin to form a colony by aggregation of the cells without fusion.