TX: Fungi Lesson
Fungi
How many of you like mushrooms on your pizza?
Have you ever had to take penicillin when you were sick?
Anyone ever have Athlete’s foot? (you do not have to answer this out loud)
How many of you ask for blue-cheese dressing with your salad or wings?
Fungi are an important part of your life, whether you realize it or not. Let’s take a look at the fantastic world of fungi!
Use the presentation to review the characteristics of the Kingdom Fungi.
The cell wall of fungi is made of chitin, a complex polysaccharide that is also found in the exoskeleton of insects. Plants have a cell wall made of cellulose.
Each multicellular fungus is composed of a highly organized, multicellular mat (mycelium) of interwoven filaments (hyphae). Many fungi produce fruiting bodies, which are reproductive structures that bear spores, their reproductive offspring. Often the only parts of a fungus that we see are these fruiting bodies.
Common Characteristics of Fungi
How Do Fungi Get Their Nutrition?
Fungi are heterotrophs. Unlike members of the plant kingdom that use chlorophyll to produce their own food, fungi do not have chlorophyll and must obtain their food from other sources.
Fungi obtain food in one, or a combination, of the following ways:
More About Parasites or Pathogens
More About Symbiosis
Fungal Reproduction
Fungi reproduce asexually by budding or by fragmentation. If the hyphae are broken (fragmentation), the pieces will grow into a completely new organism.
Some fungi, like bread mold, can release spores that are produced asexually. Spores are microscopic, non-motile cells that can develop into a new organism. Spores are produced by sporangia, which in some species form at the tips of hyphae. Spores can be dispersed by water, by wind, or by animals. When spores land in an optimal environment, the hyphae begin to grow out of the spore. Spores can be used for asexual or sexual reproduction, depending on the fungus. Yeasts reproduce by an asexual process called budding. In this process, the yeast cell pinches itself off to produce a small offspring cell as shown in the image above.
Each taxon of Fungi has different, specialized structures that ultimately produce spores. You will learn about these structures in the Fungal Classification section below.
Steps of the Fungus Life Cycle:
See description of diagram Links to an external site.
The life cycle of a fungus begins as a spore (the reproductive body) that grows when conditions are right. Out of the spore wall grows a hypha that looks like a clear, microscopic fingertip. The body of the fungus is made up of a network of hyphal threads collectively called the mycelium. The mycelium grows in soil, within dead wood, or on living organisms. This is the part that is usually visible.
When growing conditions are favorable (moisture, food source), the mycelium develops fruiting bodies, such as mushrooms or as shelf fungi. These fruiting bodies will produce the new spores in structures called sporangia. Spores are very small and can be blown or carried by water a great distance and remain dormant until the environment is sufficiently moist.
How are Fungi Classified?
They are grouped based on their type of sexual reproduction. The four groups we will study are:
- Zygomycota
- Ascomycota
- Basidiomycota
- Deuteromycota
Helpful vs Harmful
Some helpful fungi (or uses for fungi) include:
- Yeast and other fungi are used in making bread, alcoholic beverages, and soy sauce. We eat some species of mushrooms and truffles as food. The production of blue cheese involves a fungus.
- Fungi are some of the world's most important decomposers. This helps to recycle nutrients and other elements throughout the environment
- Lichens and other fungi form symbioses with organisms to benefit the ecosystem
- The antibiotic penicillin, is derived from a fungus
Some harmful fungi (or characteristics) include:
- Fungi can cause animal diseases or other health issues (ringworm, athlete's foot, candida, bat fungus)
- Trees and crops can be damaged by fungal infections (Dutch Elm Disease, Chestnut blight)
- Humans can be allergic to fungi and/or their spores
- Some fungi are poisonous
Fungi Challenge and Before You Go
Practice Time! Use the knowledge you learned from the lesson to complete the practice activities below.
Before You Go You Need To Know
The following key points are from the explore section of the lesson. You must know the following information before moving to the next lesson. This is just a summary of the key points.
- What are the characteristics of Fungi?
- Eukaryotic, multicellular (except for yeast, which is unicellular), heterotrophs, cell wall
- How are Fungi classified?
- Based on how they reproduce
- How are Fungi helpful and Harmful?
- Helpful: food, medicine, decomposers
- Harmful: disease, some are poisonous, some people may be allergic, and some cause disease in plants
IMAGES CREATED BY GAVS