Exploring Fungi: Structure, Function, and Ecology

1. Chapter 21 Fungi

2. 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

3. Chitin • A complex carbohydrate that makes up the cell walls of fungi

4. 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

5. Structure and Function of Fungi • All fungi are multicellular with the exception of yeast • Multicellular fungi are composed of thin filaments called hyphae

6. Structure and Function of Fungi

7. Fungus Structure • The bodies of multicellular fungi are composed of many hyphae tangled together into a thick mass called a mycelium

8. Fungus Structure

9. Fruiting body • The reproductive structure growing from the mycelium in the soil that you recognize as a mushroom

10. Fungi reproduction • Most fungi reproduce both asexually and sexually

11. Spore • A reproductive cell that is capable of growing into a new organism by mitosis alone • This is how fungi spread

12. Fungal spore

13. Fungi reproduction • Sexual reproduction involves two different mating types (+ and -) • When two hyphae of opposite mating types meet, their nuclei fuse together

14. Types of fungi

15. zygomycetes

16. Sac Fungi

17. Yeast

18. Club Fungi

19. Imperfect fungi

20. 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

21. 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

22. All Fungi Are Heterotrophs • Many are saprobes • Others are parasites • Others are symbionts that live in close and mutually beneficial association with other species

23. Saprobes • Organisms that obtain food from decaying organic matter

24. Carnivorous Fungi • Pleurotus ostreatus

25. 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

26. 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

27. Cordyceps

28. Symbiotic Relationships • Some fungi form symbiotic relationships in which both partners benefit

29. Lichens • Symbiotic association between a fungus and a photosynthetic organism

32. 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

33. 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