SXConline
Bio Diversity
Yeast

Objectives:

  1. To know about the vegetative structures.
  2. To know about the reproductive structures and mode of reproduction

 

Requirements:

Apparatus        : Dissection Box

Material           : Yeast Cake, Permanent Slides

 

Observations:

Visual: Yeast has granular body of white colour found in the form of cake or powder. The plant is achlorophyllous and shows the heterotrophic mode of nutrition.

Microscopic: It is unicellular plant. The cell is oval in shape and contains outer cell wall of fungal cellulose or chitin. Internally there is the peripheral granular cytoplasm around the large central vacuole. A prominent nucleus lies at the side of the vacuole. A bud scar and a birth scar is present towards the pole.

 

Reproductive Structures:

Yeast reproduces asexually by budding in favourable condition. Karyokinesis occurs and one of the nucleus moves in the bud and other remains in the mother cell. The bud may remain attached with each other to form a long chain known as pseudomycelium. The cells of the pseudomycelium when separate exist independently.

 

Classification and Identification:

Kingdom         : Plantae (Presence of cell wall and large central vacuole)

Sub-kingdom  : Cryptogamae (Non-flowering plants)

Division           : Thallophyta (Thallus body, no tissue differentiation, absence of vascular tissue, no    embryo formation, unicellular reproductive structure)

Sub-division    : Fungi (Achlorophyllous, heterotrophic, cell wall made up of fungal cellulose)

Class                : Ascomycetes (Mycelium septed, rarely unicellular, ascospores are formed in ascos)

Genus              : Saccharomyces (grows abundantly in sugary medium, unicellular, reproduce asexually by budding, presence of pseudomycelium)

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