Fungi

1
Fungi

• Chapter 21

2
The Kingdom Fungi

• Section 1

3
What are Fungi?

• Fungi are eukaryotic heterotrophs that have cell
  walls
• The cell wall is made of chitin, the same
  material that makes up the external skeletons of
  insects
• Fungi digest their food outside of their bodies
  and then absorb it
• Many feed by absorbing nutrients from decaying
  matter
• Others live as parasites

4
Structure and Function of Fungi

• Yeasts unicellular
• All other fungi multicellular
• Composed of thin filaments called hyphae
• Some hyphae have cross walls, others do not

5
Fungus Structure

• Mycelium many hyphae tangled together into a
  thick mass
• Fruiting Body reproductive structure

6
Reproduction in Fungi

• Most fungi reproduce sexually and asexually

7
Reproduction in Fungi

• Asexual Reproduction

• Sexual Reproduction

• Hyphae break off and begin to grow on their own
• Some fungi produce spores, which scatter and grow
• Sporangia structures that produce spores

• Sexual reproduction involves two mating types
  (plus) and (minus)
• Hyphae of opposite mating types meet and fuse,
  bringing and nuclei together in one cell

8
How Fungi Spread

• Many fungi produce dry spores that scatter easily
  in the wind
• If these spores are to germinate, they must land
  in an environment with the proper combination of
  temperature, moisture, and food so they can grow
• Other fungi are specialized to lure animals,
  which disperse spores over long distances

9
Classification of Fungi

• Chapter 21

10
Classification of Fungi

• Fungi are classified according to their structure
  and method of reproduction.
• The four main groups of fungi are
• Common molds (Zygomycota)
• Sac fungi (Ascomycota)
• Club fungi (Basidiomycota)
• Imperfect fungi (Deuteromycota)

11
Common Molds

• Zygomycetes familiar molds that grow on meat,
  cheese, and bread
• Have life cycles that include a zygospore
  (contains zygotes formed during the sexual phase
  of the molds life cycle)

12
Structure and Function of Bread Mold

• Black bread mold (a zygomycete) has two types of
  hyphae
• Rhizoids - rootlike hyphae that penetrate the
  bread's surface
• Stolons - stemlike hyphae that run along the
  surface of the bread
• Reproduce both sexually and asexually

13
Life Cycle of Black Bread Mold
14
The Sac Fungi

• Members of the phylum Ascomycota
• More than 30,000 species
• Names for the ascus a reproductive structure
  that contains spores
• Life cycle includes both sexual and asexual
  reproduction

15
Life Cycle of Sac Fungi
Sexual Reproduction
16
Yeasts

• Unicellular fungi
• Yeasts reproduce sexually and asexually
• Budding the process of asexual reproduction in
  yeasts
• Dry granules of yeast contain ascospores, which
  become active in a moist environment

17
The Club Fungi

• The phylum Basidiomycota, or club fungi, gets its
  name from a specialized reproductive structure
  that resembles a club
• The spore bearing structure is called the
  basidium
• Found in the gills on the underside of mushroom
  caps
• Has a complicated life cycle

18
Life Cycle of Club Fungi
19
The Diversity of Club Fungi
20
The Imperfect Fungi

• Phylum Deuteromycota
• Cannot be placed in other phyla because
  researchers have never been able to observe a
  sexual phase in their life cycles
• The species Penicillium notatum is a mold that
  frequently grows on fruit
• Source of the antibiotic penicillin

21
Ecology of Fungi

• Section 3

22
All Fungi are Heterotrophs

• Rely on other organisms for their energy
• Many are saprobes organisms that obtain food
  from decaying matter
• Some are parasites harm other organisms while
  living on or in them
• Some are symbionts live in mutually beneficial
  association with other species

23
Fungi as Decomposers

• Fungi play an essential role in maintaining
  equilibrium in nearly every ecosystem
• Fungi recycle nutrients by breaking down the
  bodies and wastes of other organisms

24
Fungi as Parasites

• Can cause serious plant and animal diseases
• A few cause human diseases

25
Plant Diseases

• Responsible for the loss of about 15 of crops
  grown in temperate regions
• Responsible for up to 50 of crop loss in
  tropical areas

26
Human Diseases

• Examples of fungus-caused disorders include
• Athletes foot
• Ringworm
• Thrush

27
Other Animal Diseases

• Deadly grasshopper infection by one fungus called
  Cordyceps

28
Symbiotic Relationships

• Some fungi form symbiotic relationships in which
  both partners benefit
• Examples
• Lichens
• Mycorrhizae

29
Lichens

• Symbiotic association between a fungus and a
  photosynthetic organism (either green algae or
  cyanobacteria)
• The algae or cyanobacteria carry out
  photosynthesis, providing the fungus with a
  source of energy
• The fungus provides the algae or bacteria with
  water and minerals and protects the green cells
  from intense sunlight

30
Structure of Lichens
31
Lichens
32
Mycorrhizae

• Association of plant roots and fungi
• Researchers estimate that 80 of all plant
  species form mycorrhizae with fungi