Home » Botany 12 » Life Cycle Yeast, Penicillium ”Biological Classification” Botany Notes Chapter 2, for Class 12-CBSE

Life cycle events of (A) Yeast and (B) Penicillium are described below :


Yeast are a group of non mycelial or  pseudomyelial ascomycetes which multiply asexually be budding or fission and where asci are not organi9sed into asococarps. These are facultative aerobes. Depending upon the mode of asexual reproduction ,  yeasts are of three types – budding yeast (e.g., Saccharomyces) , fission yeast (e.g., Schizosccharomyces) and helobial yeast (both  budding and fission, e.g., Saccharomycoides ). Yeasts in which main characteristics, but where ascus formation is not reported, are called false yeasts, e.g., Candida, Mycoderma, Geotrichum, Cryptococcus (false yeasts belong to deuteromycetes),

Life cycle of Yeast

It is a saprophytic fungus found on substratum which is rich in sugars, e.g., sugarcane juice, fruits (banana, plums, grapes), milk etc.

Structure : this a circular or elliptical , unicellular, colourless fungi not having a typical mycelium, their cell wall contains, mannans, glucans, lipids , proteins and chitin, protoplasm of yeast can be differentiated into two regions. Outer region called ectoplasm in the form a thin layer and endoplasm which is granular. The protoplasm has stored foods in  the form of glycogen bodies and volutin granules and fats. Mitochondria and ribosomes are found in the cytoplasm.

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