Lesson 7: Fungi Flashcards
What are fungi?
some of the most common but least visible organisms on Earth; often out of sight like underground or within other organisms
Examples of fungi
mushrooms, toadstools, mold spores
Why are fungi important?
- 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
What does symbiotic (relationships) mean?
a biological relationship/interaction between two different organisms
Why are fungi useful?
- 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)
Symbiotic fungi: mycorrhizae
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
Symbiotic fungi: lichens
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
How can fungi be harmful?
- some fungi are responsible for diseases that can affect both plants and animals
- examples: rot wood, ringworm, corn smut, pneumonia, etc.
Classification of fungi
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
Difference between plants and fungi?
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
Chytridiomycota (chytrids)
- they are the only fungi with swimming spores
- most are saprophytes
- they can be single-celled or multicellular
How many phylas do fungi have?
fungi has 5 phyla.. they evolved from common aquatic protist ancestor
- Chytridiomycota (chytrids)
- Zygomycota (zygomycetes)
- Glomeromycota (ascomycetes)
- Ascomycota (ascomycetes)
- Basidiomycota (basidiomycetes)
Zygomycota (zygomycetes)
- they include some familiar bread and fruit molds
- most are soil fungi
- many are used commercially
- many are parasites of insects
Glomeromycota (glomeromycetes)
all form symbiotic relationships with plant roots
Ascomycota (ascomycetes)
- many, such as yeast, are useful to humans
- some cause serious plant diseases
Basidiomycota (basidiomycetes)
- they include mushrooms, puffballs, and bracket fungi
- most are decomposers
- some form symbiotic relationships with plants
What are the two reasons to why fungi adapt?
- digestion
- reproduction
Fungi adaptation by digestion
- 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
Fungi adaptation by reproduction
- We see the “fruiting body” (i.e. the spores) which are dispersed for reproduction
- Can reproduce sexually, asexually or both
- This varies throughout Kingdom
Review fungi reproduction on its own
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
Fungi reproduction
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
