1. Chapter 22 Fungi
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
Mycelium
Septa

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. Specialized hyphae produce stalks
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 multicellular hyphae 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. Chytrid fungi, 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. Chytrid fungi, 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. **Batrachochytrium dendrobatidis
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
Common black bread mold is an example
Zygosporangium is a tough capsule that cantinas zygote

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

30. **Zygomycete pilobolus
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 fungi sexual 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 fungi sexual 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 fungi ascomycota
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 fungi sexual 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
Basidiocarps form at outer edges of large mycelial mats, mycelial grow out from central starting poiint and form expanding ring of hyphae, secually a ring of mushrooms appears.

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 fungi asexual reproduction
Rare
Does occur in some rusts and smuts

43. Life cycle of basidiomycota

44. Club fungi

45. Which type of fungi was classified with protists until recently?
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
Chytrids are unicellular like most protists but are now classified as fungi

46. Fungal partnerships Fungi form Partnerships Lichen
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 Chytridiomycota Zygomycota Ascoymycota Basidiomycota
Method of reproduction
Structures
Habitat
Example(s)
Chytridiomycota
Zygomycota
Ascoymycota
Basidiomycota

51. 22.3 Fungi and humans
Fungi are used for food, medicines, research, alternative fuels and pest control
Most familiar as a food
Provide flavor and color of blue cheese
Yeasts are used in baking, brewing, and winemaking
Produce citric acid that is used in soft drinks and candies
Some, liketruffles, are worth $1,000 per pound

52. Produce the antibiotic penicillin and cephalosporin
Black bread mold produces cortisone
Used to treat skin rashes and to reduce joint swelling
Yeast cells modified to make vaccine for hepatitis B.
Yeast also produces gasohol, a fuel alternative
Fungal insect parasites are used to kill crop-destroying insects
Helps reduce use of harmful pesticides

53. Fungi and the ecosystem
Fungi play important ecological roles by decomposing organic matter and by breaking down and absorbing minerals from rocks and soil
Main role in ecosystem decomposition
Can also break down wood
Release nutrients that other organisms can then use
Fungi release nutrients other organisms can use
Without fungi, these nutrients might not be available for use again

54. Fungi and the ecosystem, cont.
Through lichens, fungi slowly break down rocks and prepare environment for other organisms
Through mycorrhizae, fungi absorb minerals from the soil and transfer them to plant roots
Almost all plants have mycorrhizae
Some, could not survive without them

55. Fungi and disease Can causes disease in plants and animals
Cause disease by absorbing nutrients from host tissues and by producing toxins.

56. Fungal infections Dermatophytes are fungi that infect skin and nails
Cause athlete’s foot, toenail fungus, and ringworm
Yeast is normal resident of body
Antibiotics, hormonal changes, or illness can cause overgrowth of yeast
Causes yeast infection in reproductive organs and in mouth

57. Fungal infections Histoplasmosis is lung infection caused by fungus
Grows in bat and bird feces
Occurs when spores are inhaled
Left untreated, is fatal

58. Fungal toxins Many produce dangerous toxins
Can cause vomitting, diarrhea, liver damage, and even death
Aflatoxins – contaminates corn, peanuts, and cottonseed
Can cause liver cancer
Indoor molds aggravate allergies
Mold toxins can be linked with pulmonary bleeding in infants