biology - chp 21 - fungi - powerpoint
TRANSCRIPT
What are Fungi?• The way in which Fungi grow from the
ground once led scientists to classify them as nonphotosynthetic plants
• However, they are not plants at all, fungi are very different
• Fungi are eukaryotic heterotrophs that have cell walls
Fungi Nutrition• Remember that heterotrophs depend on other
organisms for food• Unlike animals, fungi do not ingest their food• Instead they digest food outside their bodies
and then absorb it• Many feed by absorbing nutrients from
decaying matter in the soil (decomposers)• Others live as parasites, absorbing nutrients
from their hosts
Structure and Function of Fungi
• All fungi are multicellular with the exception of yeast
• Multicellular fungi are composed of thin filaments called hyphae
Fungus Structure• The bodies of multicellular fungi
are composed of many hyphae tangled together into a thick mass called a mycelium
Fruiting body
• The reproductive structure growing from the mycelium in the soil that you recognize as a mushroom
Spore
• A reproductive cell that is capable of growing into a new organism by mitosis alone
• This is how fungi spread
Fungi reproduction• Sexual reproduction involves two
different mating types (+ and -)
• When two hyphae of opposite mating types meet, their nuclei fuse together
Ecology of Fungi• Fungi have been around since life first
moved onto land• Paleontologists think that fungi helped early
plants to obtain nutrients from the ground• Their early appearance suggests that fungi
may have been essential to plants successful colonization of the land
• Overtime, fungi have become an important part of virtually all ecosystems
Edible and Inedible Mushrooms
• Many types of mushrooms are considered delicious
• Although wild mushrooms are edible, many are poisonous
• You should never pick or eat mushrooms in the wild
• Leave mushroom gathering to the experts
All Fungi Are Heterotrophs
• Many are saprobes
• Others are parasites
• Others are symbionts that live in close and mutually beneficial association with other species
Fungi as Decomposers• Fungi play an essential role in
maintaining equilibrium in nearly every ecosystem
• They recycle nutrients by breaking down the bodies and wastes of other organisms by releasing digestive enzymes
Fungi as Parasites• As useful as many fungi are
others can infect both animals and plants and cause diseases
• Ex.) Wheat rust, athelets foot, Candida, Cordyceps
Lichens• The algae or cyanobacteria - Carries out
photosynthesis providing the fungus with food
• The fungus provides the algae or bacteria with – water and minerals that it collects and also protects the delicate algae cell
• Lichens are often the first organisms to enter barren environments
Mycorrhizae
• Symbiotic relationship between plant roots and fungi
• Fungi allow plants to – absorb more water and minerals
• Fungi also release enzymes that – free nutrients into the soil
• Plants provide fungi with – the products of photosynthesis