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Chapter 22 Fungi

Chapter 22 Fungi. Biology II – Loulousis . 22.1 Characteristics of fungi. Fungi grows in one place until its food runs out Before it dies, it releases millions of spores that float through the air until they find food Cycle begins again. What are fungi?.

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Chapter 22 Fungi

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  1. Chapter 22Fungi Biology II – Loulousis

  2. 22.1 Characteristics of fungi • Fungi grows in one place until its food runs out • Before it dies, it releases millions of spores that float through the air until they find food • Cycle begins again

  3. What are fungi? • »All fungi share three characteristics • 1. Threadlike bodies • 2. Cell walls have chitin • 3. Heterotrophic

  4. 1. Fungi have threadlike bodies • Made of long slender filaments • Filaments weave together to form fungus body and reproductive structures • Most filaments are loosely woven • Reproductive structures are tightly woven • Like mushrooms

  5. Fungi colors • Fungi get their color from chemicals that form during metabolic processes • Most of the colorful chemicals are toxic

  6. 2. Fungal walls contain chitin • A tough carbohydrate found in the cell walls

  7. 3. Fungi are heterotrophic • Fungi are not plants • Do not contain chlorophyll, not autotrophs • Obtain nutrients by secreting digestive enzymes that break down organic matter in their environment • Absorb decomposed molecules • Absorb nutrients • non-living matter • Leaves, branches, dead animals, & waste • Resource recyclers

  8. Structure and function • »Fungal body is made of filaments, which increase the surface area allowing fungus to absorb nutrients more efficiently

  9. Structure of a Mushroom

  10. Body Structure • Hypha- a filament of fungus, threadlike • These cells are haploid and identical • Have cell walls called septa that separate • Mycelium- mass of fungal filaments composes body • Meters long, underground • Sometimes form root-like structures rhizoids that hold fungi in place and absorb nutrients Hyphae Septa Mycelium

  11. Hyphae structure

  12. Obtaining nutrients Ringworm • Release enzymes to break down organic and inorganic matter for nutrients • Absorb across cell walls • Saprobes- absorb nutrients from dead organism • Recycle nutrients in ecosystem • Parasite-absorb nutrients from living host • Cause disease like athlete’s foot and ringworm

  13. Reproduction • »What is the difference between sexual and asexual production of spores in fungi? • Sexual – spores are produced by meiosis • Allows for genetic diversity • Asexual - spores are produced by mitosis • Allows for rapid dispersion • Most fungi do both asexual and sexual reproduction

  14. Sexual reproduction • Fused hyphae form sexual reproductive structure (like mushroom) • Spores form through fusion of two genetically different nuclei. • Now the nuclei are diploid and undergo meiosis to produce haploid spores

  15. Asexual reproduction • Specialized hyphae produce stalks • At tips of stalks haploid spores are produced by mitosis • Genetically identical to parent • Imperfect fungi – fungi without a sexual stage

  16. Yeast • Unicellular stage of fungi • Reproduce asexually by budding • Occasionally form multicellularhyphae and reproduce sexually

  17. mold • Rapidly growing, asexually reproducing stage of some types of fungi • “mold” refers to asexual phase

  18. 22.2 Groups of fungi • Modern fungi classified into four phyla • Chytridomycota (chytrids) • Zygomycote (zygote fungi) • Ascomycota (sac fungi) • Basidiomycota (club fungi) • Classified based on type of reproductive structures they form

  19. Chytrid fungi • Date back 500 million years • Earliest fungi produced spores and gametes with flagella • First fungi probably appeared in water • Only group of modern fungi in water chytrids

  20. Chytridfungi, cont. • Have chitin in their cell walls • Digest food outside their bodies • Produce hyphae that form rhizoids • Hold chytrids in place and absorb nutrients . • Sexual reproductive structures contain spores.

  21. Chytridfungi, cont. • Most are aquatic • Can live on moist land • Mainly saprobes • Which…feed on dead algae or plants • Some are parasites • Common parasites of aquarium fish • Reason for decline in amphibians in the wild

  22. **Batrachochytriumdendrobatidis • One of biggest threats facing amphibians worldwide • Mechanism by which it kills is unknown • No known treatment once infected

  23. Zygote fungi • Common member of phylum Zygomycota • Named for sexual reproductive structures that produce zygotes inside a zygosporangium

  24. Zygote fungi sexual reproduction • Begins when hyphae from two mating types join • Different mating types not referred to as male and female • Why? Because they are physically identical • Instead “+“ and “–”

  25. Zygote fungi sexual reproduction • Tough capsule called zygosporangium forms • Resistant to? Hot, cold, and dry conditions • When conditions are right, nuclei fuse to form diploid (2n) zygotes • Zygotes undergo meiosis • Zygosporangium germinates, which produces a sporangium that releases haploid spores.

  26. Zygote fungiasexual reproduction • More common than sexual reproduction • Haploid spores are produced in sporangia at the tips of hyphae • Haploid spores produced by mitosis • Haploid spores are carried by wind to new places rhizopus

  27. Life cycle of zygote fungi

  28. Zygote fungi • Usually live in soil • Feed on decaying plant and animal matter • Some species of Rhizopus can cause cancer

  29. Check Point • Where does meiosis take place in zygote fungi? • Zygosporangium

  30. **Zygomycetepilobolus • Grows in animal dung • Produces reproductive structures about 5 to 10 mm high • Can eject spores up to 2 m at a velocity near 50 km/h

  31. Sac fungi • Phylum Ascomycota • Characterized by an ascus • Saclike sexual reproductive structure that produces spores • Ascus means “sac”

  32. Sac fungisexual reproduction • Hyphae of different mating types grow together • Hyphae fuse to form a bridge • The nuclei pair up, one + and one – • Divide to form mass of hyphae that contain two nuclei per cell

  33. Sac fungisexual reproduction • In most sac fungi, mass is dikaryotic, having two nuclei • Forms structure called ascocarp • Cells in ascocarp becomes saclike asci • Nuclei fuse and undergo meiosis • Haploid spores are released

  34. Sac fungi asexual reproduction • Usually reproduce asexually • Asexual spores called conidia form by mitosis on hyphae called conidiophores • Conidia form in chains and are not covered • Spores carried by wind to germinate

  35. Life cycle of ascomycota

  36. Check Point • In sac fungi, which structure is dikaryotic? • Answer: ascocarp

  37. **Sac fungiascomycota • Cause many plant diseases • Wiped out virtually all chestnut trees in US around 1980 • Resistant cultivars are now being planted • Also known for important contributions to human health • Penicillum – antibiotic penicillin

  38. Club fungi • Phylum Basidiomycota • Include mushrooms, toadstools, puffballs, jelly fungi, shelf fungi, rusts and smuts • Larges known club fungus in Oregon is 3.5 miles across! • Characterized by a basidium • Which is a clublike sexual reproductive structure that produces spores

  39. Club fungisexual reproduction • Specialized hyphae of different mating types grow together • Hypha from one fuses with hypha from another forming dikaryotic cell • Nuclei remain separate as the cell grows into new mycelium, in which cell has 2 nuclei • Grows rapidly • When conditions are right, mycelia form reproductive structure called basidiocarp • Ex – mushroom

  40. Sexual reproduction Continued • Under basidiocarp there are club-shaped cells called basidia in which the two nuclei fuse • meiosis occurs and spores produced • Spores carried by wind, then grow

  41. Stop and think • What might be the reproductive advantage of having gills on the underside of the mushroom? • Protect spores from rain or make it easier for spores to disperse.

  42. Club fungiasexual reproduction • Rare • Does occur in some rusts and smuts

  43. Life cycle of basidiomycota

  44. Club fungi

  45. Check Point • Which type of fungi was classified with protists until recently? • A. chytrid fungi • B. club fungi • C. sac fungi • D. zygote fungi • Answer: A chytrid fungi

  46. Fungal partnerships • Fungi form Partnerships • In a mutualistic relationship.. Both members benefit • Lichen • Fungus with photosynthetic partner • Photosynthetic partner provides carbohydrates • Fungus provides protected environment, vitamins, minerals • Can survive in extreme environments • Can be damaged by chemical changes • Serve as living indicators of air pollution

  47. Fungal partnerships • Mycorrhiza • Fungi and roots of most plants • Photosynthetic partner provides carbohydrates • Fungus provides phosphorus and mineral from soil to roots

  48. lichen • Partnership between fungus and photosynthetic organism such as cyanobacteria or green alga

  49. mycorrhiza • Association between fungus and roots of nearly ALL plants

  50. Fungi phyla

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