Lecture 21 Flashcards
2 major groups of fungi?
Yeast & mold
What is this grouping (fungi) based on
body plan
Which group of fungi are almost always found as unicellular organisms?
Yeast
Which of the 2 groups of fungi always form hyphae (the other group only rarely forms hyphae)?
mold
What is the difference between hypha (pl. hyphae) and mycelium (pl. mycelia)?
A mycellium is made up of hyphae that have branched.
Are hyphae made up of 1n or 2n cells?
1n
How is the function of hyphae in a fruiting body different from the hyphae that form mycellium?
The hyphae in a fruiting body function in reproduction (spore production) while the hyphae that form mycelium can be involved in digesting & absorbing nutrients as well as in reproduction. In other words, the hyphae in a fruiting body only function in reproduction (not involved in nutrition).
What is the name of the structure that looks white and slightly brownish “fuzz”? (rotten strawberries)
Mycellia
do spores, hyphae, yeast have a cell wall?
yes.
What is a spore?
A single-celled reproductive structure that is dispersed into the environment & can grow into a hypha.
2 structures that contain spores
Sporangia & fruiting bodies.
Considering fungi’s mode of nutrition, which of the following organelle(s) would you expect to see an abundance of? Justify your answer.
vesicles. Golgi. rER.
While you will have all of these, the question is referring to the fact that fungi secrete exoenzymes in order to decompose organic matter; these exoenzymes are made by the endomembrane system
Fungi characteristics
- Eukaryotes, most multicellular
- Decomposers (by def’n are heterotrophic): nutritional mode & role in ecosystem
- Cell walls (made of chitin): can withstand osmosis (like plant cells, won’t lyse in water)
- Sexual (genetic diversity) & asexual reproduction
- Non-motile: has major impact on their “lifestyle”.
- haploid cells
where do fungi live?
Grow best in moist LAND habitats but found almost everywhere on land (wherever organic material is present)
Mostly underground
Some live in digestive tract of sheep & cattle
Grow on bread, strawbs, animal poo
Almost all live in plant roots
Most yeasts, morels, lichens, plant roots
Mushrooms, on tree trunks
fungi tolerance (living conditions)
Can tolerate huge range of pH (2-9)
Some can grow in salt, sugar (unlike most bacteria)
Wide temperature range: Can grow even in fridge
Nutrition of fungi? how is that done
Heterotrophic
Secrete exoenzymes: Digest food then absorb digested molecules, + minerals, vitamins, water either directly across the plasma membrane or by cytosis
Decompose (break down) dead organic material using exoenzymes (saprophytic)
- recycle vital nutrients (organic molecules & minerals)
- essential for most terrestrial ecosystems (along with bacteria)
Main storage carb in fungus is __
glycogen (as in animals).
YEASTS: mostly _
UNICELLULAR
Most MOLDS are : __
MULTICELLULAR
Yeast reproduce mostly_
asexually (mitosis) (budding)
but sometimes sexual reproduction by release of 1n spores from 2n sporangia
molds are mostly made up of?
hyphae
how does hyphae form?
When a fungal spore (single cell) lands in a suitable spot, it germinates then undergoes mitosis to form a multicellular hypha
Mitosis of haploid cells of fungi leads to __
formation of a hypha
Hyphae can branch to form:
mycelium (used to obtain nutrients) (FOOD)
sporangia or fruiting bodies (for reproduction)
what does Mycelia do
Infiltrate organic matter & absorb nutrients
world’s biggest and oldest fungi?
The Humongous Fungus Armillaria solidipes is among the largest and oldest living organism
Sporangia?
structure where spores are made
are Spores motile?
Spores are non-motile
Dispersed by wind, water, or animals
how are spores dispersed?
Dispersed by wind, water, or animals
asexual reproduction in fungi? (how and what’s the result)
asexual reproduction by mitosis, spores released from sporangia
1n Spores
↓ Mitosis
1n Hypha
↓ Mitosis
1n Sporangia
differential gene expression
1n Spores
sexual reproduction in fungi? (how and what’s the result)
meiosis produces genetically distinct 1n spores that are released from sporangia/fruiting body
Meiosis of 2n cells: makes four 1n cells Each 1n cell can grow into a sporangium through mitosis Release of spores Formation of hyphae Sexual or asexual repro
Shape and size of fruiting bodies depends on what?
The shape & size of fruiting bodies depends on fungal species & whether spores are dispersed by water, wind, or animals
Ecological Significance of Fungus
Most fungi are DECOMPOSERS. Get nutrients from dead organic matter: fallen trees, animal corpses…
Symbiotic relationships:
Mutualism: Mycorrhizae, lichens, & some cases with animals
A small fraction are Parasites: cause disease/kill plants & animals
__& __are the major decomposers of ecosystems.
bacteria and fungi
how do fungi penetrate on large pieces of organic matter (unlike bacteria)
fungi can use their hyphae to penetrate larger pieces of organic matter (are found on surface & within the matter)
Mycorrhizae ?
Type of fungus that forms a mutualistic relationship with plants (lives in their roots)
Mycorrhizae colonize the roots of over 90% of all vascular plants & are present in nonvascular plants
Mutualism: b/w a fungus + a phototroph (algae or cyanobacterium) . who benefits what
Phototroph provides: organic food molecules
Fungus provides a home: ie a suitable physical environment for growth, CO2, water & minerals
Economic importance of fungi
Mutualism, parasitism have economic impacts
Fungi also source of medicines
- Antibiotics
importance of fungi on Food & drink
Baker’s & brewer’s yeast
Make alcohol, release CO2 by fermentation
Sugar from fruits (ex grapes) → alcohol in wine
Sugar from grains (ex barley) → alcohol in beer
Sugar + dough → CO2 bubbles make bread rise
