Lesson 7: Fungi

Question 1

What are fungi?

Answer 1

some of the most common but least visible organisms on Earth; often out of sight like underground or within other organisms

Question 2

Examples of fungi

Answer 2

mushrooms, toadstools, mold spores

Question 3

Why are fungi important?

Answer 3

• decompose matter and thus are responsible for cycling the nutrients that are essential for healthy growth of other organisms
  Example: Mycelium breaks down and absorbs the necessary raw materials needed for plant growth and development
• fungi engage in important symbiotic relationships with plants to help them obtain nutrients

Question 4

What does symbiotic (relationships) mean?

Answer 4

a biological relationship/interaction between two different organisms

Question 5

Why are fungi useful?

Answer 5

• used in the food industry (yeast is responsible for bread rising, beer fermenting, and the veins in blue cheese)
• also used in medicine (used in Chinese medicine, used to develop antivirals, antibiotics, and in cancer therapy)

Question 6

Symbiotic fungi: mycorrhizae

Answer 6

Symbiotic relationship of hyphae (branching structure of fungi) of certain fungi and roots of some plants

• the fungus’s hyphae and the roots of plants share a relationship
• the fungi is using/benefitting from the sugar and nutrients gained from the plant; plant can absorb nutrients from the soil like Phosphorus; fungi recycles nutrients for the plant and the plant provides the nutrients for the fungi
• this is important because some plants cannot germinate (beginning to grow from a seed) without these mycorrhizae
• impacts the development of food in harsh climates

Question 7

Symbiotic fungi: lichens

Answer 7

Combination of green algae or cyanobacteria and a fungus growing symbiotically
- photosynthetic cyanobacteria and a sac fungus

Either fungus growing together with green algae or growing together with cyanobacteria (growing with bacteria or able to grow well w algae)

Mycelium threads of fungus wraps around photosynthetic cells
- thus the fungus provides the algae with CO2, H2O, and support (nutrients)
- in return, the algae provides the fungus with carbohydrates
- this is a mutually beneficial interaction
- this is an important relationship in detecting air pollutants

Question 8

How can fungi be harmful?

Answer 8

• some fungi are responsible for diseases that can affect both plants and animals
• examples: rot wood, ringworm, corn smut, pneumonia, etc.

Question 9

Classification of fungi

Answer 9

used to be classified with plants.. they share the following characteristics:
- both are eukaryotic and have numerous organelles
- both have a cell wall present
- most are anchored in soil
- both are stationary
- both can reproduce sexually asexually, or both

Question 10

Difference between plants and fungi?

Answer 10

Plants:
- Only 1 nucleus per cell
- Most are autotrophs
- Store ENERGY as starch
- Have roots
- Cell wall made up of cellulose
- Reproduce by seed

Fungi:
- Can have many nuclei
- Are heterotrophs
- Few storage molecules
- No roots
- Cell wall made of chitin (a polysaccharide)
- Do not reproduce by seed

Question 11

Chytridiomycota (chytrids)

Answer 11

• they are the only fungi with swimming spores
• most are saprophytes
• they can be single-celled or multicellular

Question 11

How many phylas do fungi have?

Answer 11

fungi has 5 phyla.. they evolved from common aquatic protist ancestor

1. Chytridiomycota (chytrids)
2. Zygomycota (zygomycetes)
3. Glomeromycota (ascomycetes)
4. Ascomycota (ascomycetes)
5. Basidiomycota (basidiomycetes)

Question 12

Zygomycota (zygomycetes)

Answer 12

• they include some familiar bread and fruit molds
• most are soil fungi
• many are used commercially
• many are parasites of insects

Question 13

Glomeromycota (glomeromycetes)

Answer 13

all form symbiotic relationships with plant roots

Question 14

Ascomycota (ascomycetes)

Answer 14

• many, such as yeast, are useful to humans
• some cause serious plant diseases

Question 15

Basidiomycota (basidiomycetes)

Answer 15

• they include mushrooms, puffballs, and bracket fungi
• most are decomposers
• some form symbiotic relationships with plants

Question 16

What are the two reasons to why fungi adapt?

Answer 16

1. digestion
2. reproduction

Question 17

Fungi adaptation by digestion

Answer 17

• Their digestion is extracellular (occurs outside the cell - fungi feed by secreting enzymes through the cell membrane)
• Once digestion has occurred, the nutrients are absorbed by mycelium, which is a mesh-like network of filaments called hyphae
• Mycelium often look like the “fuzz” we associate with mold
• Instead of taking food inside their bodies, fungi grow next to or within their food source and then release digestive enzymes into surroundings (then the fungi absorb the nutrients through cell membranes of the hyphae

Question 18

Fungi adaptation by reproduction

Answer 18

• We see the “fruiting body” (i.e. the spores) which are dispersed for reproduction
• Can reproduce sexually, asexually or both
• This varies throughout Kingdom

Question 19

Review fungi reproduction on its own

Answer 19

Fungal reproduction will include stages of sexual and asexual reproduction..
- fungi possess haploid nuclei (i.e a single set of chromosomes)
- most other eukaryotic organisms possess diploid nuclei

Life cycle of a basidiomycete: each spore contains a haploid nucleus; these spores germinate and produce hyphae with single nuclei separated by septa

Question 19

Fungi reproduction

Answer 19

When two hyphae come in contact with one another, two of their cells can fuse which forms a dikaryotic cell with two separate haploid nuclei

more info:
- This cell them grows into a large new mycelium made of cells with two haploid nuclei
- When the mycelium becomes large and mature, it may produce a mushroom cap
- On the underside of the cap, spore-producing structures called basidia form on the mushroom’s gills
- Within the basidia, the two haploid nuclei fuse which forms a zygote
- The zygote undergoes meiosis which results in the production of four haploid spores
- The spores are then released into the environment