At some point in a student’s life, he or she will have to learn about fungi. This typically happens when the student reaches high school biology. While learning about fungi can bring on yawns and blank stares, it doesn’t have to.
Learning about fungi can be fun. Here are some ways to make it more interesting.
Learn the Defining Characteristics of Kingdom Fungi
Fungi are Composed of Eukaryotic Cells.
All cells can be divided into two major types.
Prokaryotic cells are the simpler of the two cell types. They have no membrane-bound organelles and they lack a nucleus. Of all living things on the planet, only bacteria and archaebacteria have prokaryotic cells.
Eukaryotic cells are the more complex of the two cell types. Eukaryotic cells have a nucleus and membrane-bound organelles—each with an important role in sustaining the life of the cell. All living things on the planet other than bacteria and archaebacteria have eukaryotic cells.
Fungi Have Cell Walls Made of Chitin.
Some types of eukaryotic cells are enclosed by an extra membrane in addition to the cell (plasma) membrane. This extra membrane is called a cell wall.
Plant cells have a cell wall made of cellulose or lignin.
The cells of fungi are enclosed in a cell wall made of chitin. Interestingly, chitin is the same rigid carbohydrate that makes up the shells of insects, shellfish, and other arthropods.
Some Fungi are Multicellular While Others are Unicellular.
When most people think of fungi, they imagine mushrooms.
While multicellular forms of fungi do exist, there are also microscopic, unicellular fungi. For example the microorganisms we collectively call “yeast”—used to make bread, wine, and beer—are fungi. So are the organisms known as mold and mildew.
Fungi are Heterotrophs.
Members of Kingdom Fungi are heterotrophs. The term “heterotroph” literally means “other feeder”. In other words, fungi do not make their own food (and thus are not autotrophs—”self feeders”).
Fungi were once included in the plant kingdom, but were given their own kingdom once it was determined that they did not undergo photosynthesis or make their own food.
Organisms in Kingdom Fungi Have Methods of Reproduction That Utilize Spores.
If you examine the gills of a mushroom with a magnifying glass, you can often find the spores. These spores are capable of producing a new mushroom when transferred to a new location.
Watch as this so-called cannon fungus shoots its spores to a new location.
Fungi Obtain Nutrition in a Unique Way Known as Extracellular Digestion.
Fungi secrete digestive enzymes into the environment to break down food molecules, then they absorb the digested material.
Fungal enzymes responsible for extracellular digestion are often capable of causing damage to nearby organisms. The redness, pain, and itching associated with yeast infections, ringworm, and athlete’s foot are the result of the action of the fungal extracellular enzymes.
Learn the Difference Between the Fruiting Body of a Fungus and its Mycelium.
A typical multicellular fungus exists as a mass of long, thread-like hyphae called a mycelium. Often, the objects we often associate with fungi (such as mushrooms or shelf fungi) are only a small part of the entire fungus. Under the fruiting body, a vast network of mycelium may exist. Mycelium can grow to enormous sizes. In fact, the mycelium of a fungus found growing underground in Oregon was measured to span 2,384 acres.
Often, when people try to remove a mushroom or other fungus from their yard, they think removing the fruiting body is sufficient. However, as long as the mycelium is left intact, the fungus will continue to grow.
As many as 90% of all terrestrial plants exist as part of a symbiotic relationship with the mycelium of a fungus called mycorrhizae. Within this mutually advantageous relationship, the fungal mycelium provides the plant with an expanded network for absorbing nutrients and water from the soil. Meanwhile, the plant supplies the fungus with food in the form of carbohydrates produced through photosynthesis.
Recent studies suggest that networks of mycorrhizal fungi link plants together in what has been nicknamed the “Wood Wide Web”. Through this network of mycorrhizal fungi, plants may share nutrients with one another or even send chemical messengers (in the form of hormones) to communicate. Watch the following video to learn more.
Learn About Lichens
Lichen are considered composite organisms.
A lichen is a symbiotic relationship between a fungus and algae. The fungus provides a moist, protective place to live while the algae provides food in the form of carbohydrates formed through photosynthesis.
Humans use lichens as a source of dyes and many animals (including caribou and reindeer) depend on lichens for food.
Because lichens are sensitive to pollution levels, they are considered indicator species. The presence of lichens is an indicator of the overall health of a region.
Explore The Benefits of Fungi
Fungi are Decomposers
Nature isn’t wasteful. Think about all of the leaves that fall to the ground each Autumn. All of those leaves contain essential nutrients such as nitrogen, carbon, and phosphorus that other living things need. Thank goodness for the decomposers!
Together with the bacteria, fungi are responsible for the decomposition of all dead matter and the recycling of nutrients (including oxygen, carbon, nitrogen, and phosphorus) back into the ecosystem. This explains why fungi are usually found growing on the forest floor or in other niches where dead organic material is found.
Fungi as Food and for Fermentation
Microscopic yeast use a process called fermentation to break down carbohydrates into energy, releasing ethanol (alcohol) and carbon dioxide as byproducts. Humans take advantage of yeast fermentation to make alcoholic drinks such wine, beer, and spirits. Bakers also use yeast fermentation and the production of carbon dioxide to make their bread rise. The familiar scent so many of us associate with bread “rising” is actually due to minute amounts of alcohol released during the fermentation process.
Fungi as the Source of Drug Discovery
A number of drugs have been produced from fungi.
You may recall that the first antibiotic was discovered after Alexander Fleming noticed that the mold which had contaminated his petri dish containing live cultures of bacteria produced a substance that inhibited bacterial growth. That mold, Penicillum notatum, was actually a fungus. You can read more about that incredible story in my blog post here.
The mold Tolypocladium inflatum is the source of cyclosporine, a drug given to patients following organ transplant to suppress the immune system and prevent organ rejection.
Medications called statins, used to lower cholesterol, were first isolated from the mold Aspergillus terreus.
Fungi are Used in Industry and in Scientific Research
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Enzymes produced by different fungal species for extracellular digestion are used industrially in the manufacture of many products including paper and textiles.
Fungi—especially the yeast Saccharomyces cerevisiae— are widely used in laboratory research. Like bacteria, yeast are capable of rapid growth, making them suitable for laboratory studies. Unlike bacteria, yeast possess eukaryotic cells, allowing them to be used as tools for studying cellular mechanisms (such as gene expression) shared by eukaryotic organisms including humans.
Research the Ways Fungi Can be Harmful
Many fungal species have been shown to cause disease in plants and animals. Some fungi act as parasites.
Fungi of genus Ophiocordyceps are responsible for causing ants living in tropical rainforests to turn into “zombie” ants. Fungal spores ingested by ants grow and form hyphae within the insect bodies. Enzymes produced by the fungus act on the insect nervous system and direct the ant to climb vegetation and latch on with its mouth where it eventually dies. The fungus then forms more spores on a specialized hyphae which protrudes from the ant’s head. As the spores fall to the ground and the cycle is repeated.
White-nose Syndrome, a disease in North American bats, is caused by a fungus. It is considered one of the worst wildlife diseases in modern times and has killed millions of bats in North America alone. Learn more about the disease in the following video.
It is estimated that 85% of all plant diseases are caused by fungi. Fungi that cause many diseases in plants—such as Dutch elm disease, potato wart, various rusts, smuts, mildews, and blights—cause billions of dollars in damage each year. Farming practices that have eliminated the genetic diversity of agricultural crops exacerbate the problem. While commercial fungicides are available, fungicide-resistant fungal strains have developed over time.
In fact, did you know that the Great Irish Potato Famine was caused by a fungus?
Hands-on Activities to Study Fungi
View Budding Yeast Under a Microscope
While able to reproduce sexually producing spores, the unicellular yeast may also reproduce asexually through a process known as budding. During budding, a small daughter cell (also called a bud or bleb) forms off of the parent cell. If you have a microscope, you can perform this activity to watch budding yeast.
- a packet of active dry yeast
- warm water (not too hot or it will kill the yeast)
- 1 tablespoon of table sugar
- microscope slide and cover slip
- medicine dropper or plastic pipette
- Mix one packet of active dry yeast with approximately 1 cup of warm water in a glass. Add the sugar and stir gently.
- Let the mixture sit for a minimum of 5 minutes. You will see bubbles of carbon dioxide start forming as the yeast begin growing and metabolizing the sugar.
- Place a drop of the yeast mixture on a slide and add a cover slip. Observe the specimen under the microscope using the low, medium, and high powers of magnification.
Below is a video of what you can expect to see. Did you ever imagine that the yeast you bake with could be so cool?
Go on a Fungus Scavenger Hunt
This activity requires no special materials; it only requires your willingness to take time to look around you to see examples of fungi. I’ll bet that you find more than you expect.
Where Can You Find Fungi in Your Home?
- On a loaf of moldy bread
- On a rotting vegetable or piece of fruit
- On cheese
- In your shower or on your shower curtain
Where Can You Find Fungi Outside?
- Lichen on trees
- Under a pile of fallen leaves
- Mycorrhizae growing in the soil underneath mushroom
Make Elephant Toothpaste
If you’ve never made elephant toothpaste, you’re missing out on a lot of fun! Yeast (a fungus) is one of the key ingredients. Check out how easy it is in this project from Home Science Tools: FOAMY FLASK | ELEPHANT TOOTHPASTE SCIENCE PROJECT
Make A Rot Museum
Make a rot museum and compare how different foods decompose due to the action of fungi. DISGUSTING SCIENCE: ROT MUSEUM
Create Your Own Compost Pile
To see fungus in action, set up your own compost pile. This can be in your backyard, or even on your kitchen counter (in an empty coffee can). Put your fruit, bread, or vegetable scraps in your pile and observe them over a series of days.
Fungi are just one kingdom of organisms I discuss in my self-paced, online Microbiology course. Students will learn all about the history of microbiology, the Germ Theory of Disease, and the different types of “germs”: viruses, bacteria, fungi, protozoa, and algae. Students proceed at their own pace through the material and directions for many hands-on activities are included.
Fungi make up one of the 6 kingdoms of living things. Studying the 6 kingdoms of life and what makes them unique is something we do during the second semester of my live, online biology class for high school. You can learn more about how the class is organized as well as what topics we cover here: Live Science Classes Taught by Dr. Kristin Moon
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