3 of Life Cycles Found in Yeast | Biology
Some of the important types of life cycles found in yeast are as follows: Guilliermond (1940) has recognized three main types of life cycles in the yeast. These life cycles are known as — 1. Haplobiontic, 2. Diplobiontic and 3. Haplo- diplobiontic. 1. Haplobiontic type: This type of life cycle is found in Schizosaccharomyces octosporus and some other yeasts. In these yeasts the vegetaive stage is predominantly haploid and the diploid stage is very short. The diploid stage is represented by the zygote cell only which undergoes meiosis immediately after nuclear fusion. Here each somatic cell acts as a potential gametangium. During sexual union two cells fuse (plasmogamy) and this is followed by the fusion of the two nuclei (karyogamy). The fusion or zygote nucleus divides thrice of which the first division is meiotic one. Now the zygote cell becomes ascus containing eight ascospores. After their liberation from the ascus the ascospores behave as vegetative cells. 2. Diplobiontic type: Th...