Fungi are eukaryotic organisms that can exist as unicellular yeasts or multicellular molds and mushrooms. They have rigid cell walls made of chitin and reproduce both sexually through spores and asexually through budding or fragmentation. Yeasts are unicellular while molds are filamentous and made up of branching hyphae. Fungi play important roles in industries like food production as well as in biodegradation and antibiotic production. Medically important fungi are classified into four divisions: Ascomycetes, Basidiomycetes, Zygomycetes, and Deuteromycetes.

1. Fungi
Anup Muni Bajracharya

2. • Fungi are eukaryotic, heterotrophic,
unicellular to filamentous, spore bearing
organisms that reproduce sexually and
asexually.

3. General properties of fungi
1.They are eukaryotic; cells contain membrane
bound cell organelles including nuclei,
mitochondria, golgi apparatus, endoplasmic
reticulum, lysosomes etc.
2.They have a rigid cell wall which is made up
of chitin.
3. Cell membrane is made up of ergosterols.

4. 4. They lack chlorophyll and are therefore
chemoheterotrophs (require organic
compounds for both carbon and energy
sources) and not autotrophic.
5. Fungi are osmiotrophic; they obtain their
nutrients by absorption.
6. They obtain nutrients as saprophytes (live
off of decaying matter) or as parasites (live off
of living matter).
7. Typically reproduce asexually and/or
sexually by producing spores.
8. They grow either reproductively by budding
or non-reproductively by hyphal tip elongation.
9. Food storage is generally in the form of
lipids and glycogen.

5. Structure of fungi
There is much variation in the structure of
various fungal species.
For example, fungi include
• the unicellular yeasts,
• multicellular molds and
• the common mushrooms.

6. Yeast
• microscopic, unicellular fungi with a single nucleus and eukaryotic
organelles.
• oval or round in shape.
• reproduce asexually by a process of budding.
• In this process, a new cell forms at the surface of the original cell, enlarges,
and then breaks free to live independently.

7. Mold:-
The main body of mold is made up of
fine, branching threads called hyphae.
These hyphae intertwined with each
other to make up a tangled web called
the mycelium.
In some fungi hyphae is divided into cell
or compartment by septum.
Septum has a central pore which allows
the movement of cytoplasm from one
cell or compartment to another.
There are three types of hyphae among
fungi.
Coenocytic or non-septated hyphae
Septate hyphae with uninucleated cell
Septate hyphae with multinucleated cell

8. Reproduction in fungi
Fungi reproduce sexually and asexually by
spores.
Asexual reproduction occurs in the fungi
when spores form by mitosis.
These spores can be conidia,
sporangiospores, arthrospores (fragments
of hyphae), or chlamydospores (spores
with thick walls).
During sexual reproduction, compatible
nuclei unite within the mycelium and form
sexual spores.
Sexually opposite cells may unite within a
single mycelium, or different mycelia may
be required.
When the cells unite, the nuclei fuse and
form a diploid nucleus.

10. Characteristics Yeast Mold
Structure
Yeast are mostly unicellular and exist
in either individually or with buds
growing on them
Mold are multicellular with tubular and
filamentous hyphae
Structural
Appearance Round or oval shaped Thread like filamentous
Color appearance
Dull color and mostly
monochromatic Wide variety of coloration
Habitat Most occur naturally in soil or ocean
Occur in any organic environment
having moist and humid atmosphere
Method of
reproduction Mainly by budding or binary fission
Mainly by spore formation (sexual and
asexual spore both)
Application or uses
Use in industries for ethanol
production, baking, food additive or
flavor etc
Used in biodegradation, bioremediation
as well as in antibiotic production
Oxygen requirement Aerobic and facultative anaerobes Strictly aerobic (obligate aerobes)
Examples
Saccharomyces cerevisiae, Candida
albicans, Cryptococcus neoformans Rhizopus, Mold, Penicillium, Aspergillus

11. Classify medically important fungi
The kingdom fungi is classified into 4 division
that are involved in medical mycology
1. Ascomycetes
2. Basidiomycetes
3. Zygomycetes
4. Deuteromycetes

12. Ascomycetes
• Sexual spore produced within a
sac like structure called ascus.
• Sexual spore are called
ascospore
• Asexual reproduction occurs by
conidia
• Ascomycetes are also known as
sac mycetes.
• Hyphae are generally septated
• Examples: Saccharomyces,
Arthroderma

13. Basidiomycetes
• Sexual spore are produced
externally on a basidium
• Sexual spore are known as
basidiospore
• Asexual reproduction occurs
by budding, fragmentation or
conidia formation
• They are commonly called as
mushroom group
• Hyphae are generally
septated
• Examples: Amanita, Agaricus

14. Zygomycetes
• Sexual spore are known as Zygospore
• Zygospore is formed by fusion of two similar cells.
• Asexual reproduction occurs by sporangiospore
• Hypahe are generally aseptated.
• Examples: Rhizopus, Mucor

15. Deuteromycetes
• No sexual stage is present
• Deuteromycetes are also
known as fungi imperfecti.
• Asexual reproduction occurs
by means of conidia.
• Most of the human and
animal pathogens are present
in this class.
• Examples: Candida,
Cryptococcus, Trichophyton,
Epidermophyton, Histoplasma