CLASS NOTES: FUNGI
(singular = fungus)
What are fungi?
Fungi are plant-like living organisms that do not contain chlorophyll.
Because they lack chlorophyll, they cannot make their own food.
Characteristics of fungi
Like plants, fungi are rooted, and do not move from place to place. They
need moisture and warmth to grow. Unlike plants, fungi cannot make their
own food; To get energy, they must take in food from other sources. Unlike
plants, fungi grow from spores, instead of seeds. The spores are carried to
new locations by air, water and animals.
Types of fungi
Four common types of fungi are MUSHROOMS, MOLD, YEAST and
MILDEW.
MUSHROOMS
Mushrooms can be seen on the ground, on fallen logs, and on living
trees. The part that we see above ground is not the entire fungus - most of
it grows underground in a wide net of cells that looks like tiny criss-crossed
plant roots. The part of the mushroom that grows above ground is the
reproductive organ of the fungus. It contains the spores that will create
new fungi, the same way that a fruit holds the seeds that will create new
plants. Just as some seeds are small enough and light enough to be
carried away by the wind, so the microscopic mushroom spores float away
on the wind, to begin life in new locations.
Mushroom Root System
Mushrooms growing on dead organisms, such as fallen logs, act as
decomposers to break down the wood and return it to the soil in a usable
form as food for plants. Mushrooms that grow on live trees are parasites.
Harmful and Helpful Mushrooms
Some mushrooms are deadly if eaten. Unless you are an expert, or have
been trained to recognize poisonous varieties, you should never eat wild
mushrooms.
The mushrooms sold in stores, however, are safe to eat, are a good source
of fiber, and have high nutritional value with very few calories.
MOLD (MOULD)
Mold, in a variety of colors, can be seen growing on bread, fruit, or in any
damp, warm area. Like the mushroom, the part that we see is only the
reproductive part of the organism. Most of the mold is too small to be easily
visible, and grows as a network of tiny, transparent, root-like threads called
hyphae. As it develops, the mold sends roots deep into the structure on
which it is growing. If mold is easily visible on food, it is a sign that the roots
have already grown deep.
Mold Hyphae and Spores (Enlarged)
Like other fungi, mold is a decomposer. It gets its food from the substance
on which it grows, and breaks down organic matter as it feeds. Mold isn’t
only found on food. It can feed off damp paper products, lint, ceiling tiles,
drywall, wallpaper, insulation, carpeting, fabric, upholstery, plants, dead
wood, and other organic materials.
Harmful and Helpful Molds
Mold is in the air all around us, and we are all exposed to it, both inside and
outside the house. It is an essential part of our world; We need it to break
down dead organic matter in the natural environment, to enrich the soil,
and provide food for plants. In the scientific field, mold is grown on citrus
fruit to make penicillin, an antibiotic used to treat bacterial infections. Mold
is also used in the food industry to flavor certain kinds of cheese.
It is mold’s ability to destroy organic matter that can make it dangerous to
us at high concentrations, and in certain conditions. Some molds cause
serious allergic reactions in people who are sensitive to it, while other
molds produce a toxin (poison) that can cause illness.
MILDEW
Mildew is an early stage of mold. It differs from mold in color, as it is
usually silvery gray or white, while mold is usually red, green, blue, or
black. Mildew also differs from mold in texture; it has a downy or powdery
texture, while mold tends to be fuzzy and slimy. growing on leaves can
damage the plant. Both mold and mildew prosper in dark, humid, damp
and poorly ventilated environments.
YEAST
Yeast are microscopic single-celled fungi. Yeast cells are egg-shaped, and
are found everywhere in the environment. Although fruit and berry skins are
among their favourite habitats, they can also be found in the spaces
between your toes, in your skin, gut, genitals, and even in crude oil. Yeast
can exist in many forms: Living, dead, liquid, dehydrated (dry), pressed or
crumbled. Yeast digest food, especially sugar, to obtain energy for growth.
Harmful and Helpful Yeast
Certain species of yeast are used to make bread, wine and beer. Nutritional
(inactive) Yeast is an excellent source of protein, and a rich source of Bcomplex vitamins that are important for normal and healthy body functions.
Yeast occurs naturally in the human body, and plays an essential part in
our digestive and immune systems.
However, not all yeast are beneficial. One species, Candida Albicans,
exists harmlessly in the human body until it encounters a weak immune
system. It then becomes the cause of conditions such as yeast infections,
diaper rash in babies, or thrush on the tongue.