General characters of molds
Course_ Mycology (theory)
Lec. no_ 2nd
4th Grade – Fall Semester 2021-2022
Instructor´s name_ Dr Ahang Mawlood
Instructor´s email_ [email protected]
Date_ 07/11/2021
What is Mycology?
Mycology is the branch of biology concerned with the
study of fungi, and yeast including
their genetic and biochemical properties,
their taxonomy and their use to human as a source
for tinder, traditional medicine, and food, as well as
their dangers, such as toxicity or infection.
A biologist specializing in mycology is called
a mycologist.
What are fungi?
The kingdom Fungi is composed of unicellular
or multicellular, eukaryotic, heterotrophic
microbes. Each fungal cell contains a full array
of organelles and is bound by a rigid cell wall
containing chitin, glucan, and/or cellulose.
Of the thousands of fungal species that are
free-living in nature or are pathogenic for
plants, only a small group are known to be
pathogenic for humans and animals. It is also
true that any fungus capable of growing at
37◦ C is a potential pathogen in a
immunocompromised host. Some fungi are
primary pathogens (e.g., Coccidioides
species) and can cause disease in immune-
normal persons.
Severity of a fungal disease is related to host
factors (immune status, general health status)
and the number of infectious propagules
(conidia or spores) inhaled, ingested, or
injected. Persons who are
immunocompromised are prone to develop
more serious disease and to be susceptible to
opportunistic fungi against which immune-
normal persons have a high level of resistance.
Where are they found?
Fungi are ubiquitous in nature, being found
in the air, in soil, on plants, and in water,
including the oceans.
Relationship of fungi with other
organism
Fungi form beneficial relationships with other
organisms. For example, mycorrhizae is an
association between the roots of plant and
fungi. Fungi also are found in the upper
portions of many plants. On the other hand,
lichens are associations of fungi and either
algae or cyanobacteria.
Mycorrhizae Lichens
Fungi are important to humans in both beneficial and
harmful ways.:
1. Bacteria with fungi act as decomposers, a role of
enormous significance. They degrade complex organic
materials in the environment to simple organic
compounds and inorganic molecule.
2. However, fungi are the major cause of plant
diseases. Over 5,000 species attack economically
valuable crops and garden plants.
Importance of fungi
Fungal Diseases. Apple scab lesions on fruit and
leaf. These lesions produce spores capable of
causing further spread of the disease.
3. Fungi, especially the yeasts, are essential to many
industrial processes involving fermentation. Examples
include the making of bread, wine, and beer.
4. Fungi is used in the manufacture of many
antibiotics (penicillin, griseofulvin and the
cyclosporine.
5. In addition, fungi are important research tools in the
study of fundamental biological processes. Such as
Cytologists, geneticists, biochemists, biophysicists for
example the yeast Saccharomyces cerevisiae is the
best understood eucaryotic cell.
The body or vegetative structure of a fungus is called
a thallus. It varies in complexity and size, ranging from
the single-cell microscopic yeasts to multicellular
molds, macroscopic puffballs, and mushrooms. The
fungal cell usually is encased in a cell wall of chitin.
Chitin is a strong but flexible nitrogen-containing
polysaccharide consisting of N-acetylglucosamine
residues.
Structure
Fungal Thalli. (a) The multicellular
common mold, Penicillium, growing on an
apple. (b) A large group of puffballs,
Lycoperdon, growing on a log. (c) A
mushroom is made up of densely packed
hyphae that form the mycelium or visible
structure (thallus).
A yeast is a unicellular fungus that has a single nucleus
and reproduces either asexually by budding and
transverse division or sexually through spore
formation. Each bud that separates can grow into a
new yeast, and some group together to form colonies.
Generally yeast cells are larger than bacteria, vary
considerably in size, and are commonly spherical to
egg shaped. They have no flagella but do possess most
of the other eucaryotic organelles
Structure of yeast
Diagrammatic drawing of a yeast cell showing typical
morphology.
A mold consists of long, branched, threadlike
filaments of cells called hyphae that form a mycelium,
a tangled mass or tissue like aggregation. In some
fungi, protoplasm streams through hyphae,
uninterrupted by cross walls. These hyphae are called
coenocytic. The hyphae of other fungi have cross
walls called septa with either a single pore or multiple
pores that permit cytoplasmic streaming. These
hyphae are termed septate.
Structure of fungi
(a)
(c)
(a) A very large macroscopic mycelium of a basidiomycete
growing on the soil. (b): Drawings of coenocytic hyphae and
hyphae divided into cells by septa.(c): Drawing of a multi-
perforate septal wall structure.
Thank you
