introduction to yeast. classification of yeast. morphology of yeast. cell wall composition of yeast. structure of yeast. plasma membrane structure of yeast. function of cell organelles.

1. Introduction to Yeast
Yeast, a type of fungus, is a unicellular microorganism belonging to the
kingdom Fungi. It plays a crucial role in various fields such as baking,
brewing, and bioethanol production. Yeast can reproduce both sexually and
asexually, and its metabolic activities have wide-ranging implications.
ks by kanchan sharma

2. Classification of Yeast
Diversity of Yeast Species
Yeast can be classified into various species,
each with unique characteristics and genetic
makeup. Some common species include
Saccharomyces cerevisiae, Candida albicans,
and Schizosaccharomyces pombe.
Evolutionary Relationships
The classification of yeast involves studying their
evolutionary relationships and genetic
divergence. This not only aids in understanding
their biodiversity but also provides insights into
their ecological roles.

3. Morphology and Structure of Yeast
Cells
Cellular Morphology
Yeast cells are typically oval or spherical
in shape and range in size from 3 to 4
micrometers. They can exist as single
cells or form multicellular structures
depending on environmental conditions.
Structural Components
The yeast cell consists of a prominent
nucleus, cytoplasm, cell wall, and
plasma membrane. Each component
has specific functions vital for the survival
and functioning of the cell.

4. Yeast is a type of unicellular fungus that contains the same
organelles as found in a mature eukaryotic cell. Here are some
key features of its structure:
•Cell Wall: The cell wall of yeasts is made up of glycoproteins,
polysaccharides like chitin, and mannoproteins.
•Vacuoles: The vacuoles in the yeast cell occupy around 20%
of the cell volume and are important for breaking down proteins,
storing nutrients, and maintaining homeostasis.
•Mitochondria: Mitochondria in yeasts play a similar role as in
plant and animal cells. They are the source of energy for
growth, respiration, and homeostasis. ATPs are produced in
yeast mitochondria by the process of oxidative phosphorylation.
•Endomembrane System: The endomembrane system of the
yeast cell consists of ribosomes, Golgi apparatus, and
endoplasmic reticulum. The system is involved in sorting,
packaging, and transporting molecules to other parts of the cell.
•Size and Shape: A typical yeast cell is about 0.075 mm in
diameter and can grow in various egg-shaped or spherical
filamentous forms.
The most common examples of yeast include Saccharomyces
cerevisiae and Candida albicans. Saccharomyces cerevisiae,
for instance, has a smooth, moist, flat, and dull or glistening
appearance. They are creamish in color.
Structure of Yeast

5. Cell Wall Composition and Function
1 Chitin and Glucans
The yeast cell wall primarily comprises
chitin and glucans, providing rigidity
and shape to the cell. These
components also play roles in cellular
integrity and environmental
interactions.
2 Protection and Defense
The cell wall acts as a protective
barrier, shielding the yeast cell from
physical and chemical stresses. It also
interacts with the external
environment and is involved in
pathogenicity in certain yeast species.

6. Plasma Membrane Structure and Function
Fluid Mosaic Model
The plasma membrane of yeast cells follows
the fluid mosaic model, consisting of
phospholipid bilayers interspersed with
proteins. This structure allows for selective
permeability and cellular signaling.
Transport and Signaling
Integral proteins within the plasma membrane
facilitate the transport of molecules in and out of
the cell, as well as mediate intercellular
communication and response to external
stimuli.

7. Cytoplasmic Organelles in Yeast
Mitochondria
Mitochondria are key organelles responsible for energy production through
oxidative phosphorylation. They play a vital role in cellular respiration and
metabolism.
Endoplasmic Reticulum
The endoplasmic reticulum is involved in protein synthesis, folding, and transport
within the cell. It consists of rough ER (with ribosomes) and smooth ER (lacking
ribosomes).
Golgi Apparatus
The Golgi apparatus is essential for processing, modifying, and packaging
proteins for secretion or transport to other cellular locations. It plays a crucial role
in intracellular trafficking.

8. Nucleus and Genetic Material in Yeast
1 Nuclear Envelope
The nucleus of a yeast cell is enclosed within a double membrane called the
nuclear envelope. This structure separates the genetic material from the rest of
the cellular components.
2 Chromatin Organization
The genetic material in yeast cells is organized as chromatin, comprising DNA
and proteins. The arrangement of chromatin influences gene expression and
cellular functions.
3 Nucleolus
The nucleolus within the nucleus is associated with ribosome biogenesis. It is
involved in the assembly of ribosomal subunits, essential for protein synthesis.

9. Mitochondria and Energy
Production in Yeast
Oxidative Phosphorylation
Mitochondria are the site of oxidative
phosphorylation, generating ATP as an
energy currency for cellular processes.
This process involves the electron
transport chain and ATP synthesis.
Krebs Cycle
The mitochondria of yeast cells play a
pivotal role in the Krebs cycle, also
known as the citric acid cycle, which is
crucial for energy production from
metabolized nutrients.

10. Endoplasmic Reticulum and Protein
Synthesis in Yeast
1 Rough Endoplasmic Reticulum
The rough ER is studded with
ribosomes and is involved in the
synthesis of membrane-bound and
secretory proteins in yeast cells
through translation and protein
folding.
2
Smooth Endoplasmic Reticulum
The smooth ER lacks ribosomes and
contributes to lipid synthesis,
metabolism, and detoxification of
drugs and other xenobiotics in yeast
cells.

11. Golgi Apparatus and Vesicle
Trafficking in Yeast
1 Vesicle Formation
The Golgi apparatus is responsible for the
modification, sorting, and packaging of
proteins into vesicles for transport to
various cellular destinations, including
secretion or other organelles.
2 Intracellular Transport
Vesicles formed by the Golgi apparatus
are involved in intracellular transport,
ensuring precise delivery of proteins and
lipids to their designated cellular locations
in yeast cells.

12. Thank
You