Next: What am I??

1
Next What am I??
One large, multinucleated cell with no cell walls
2
Revisiting the Protists
??
3
Kingdom (?) Protista

• 60,000 known species of mostly unicellular
  eukaryotes
• Other eukaryotes that are not Fungi, Plants or
  Animals also included

4
The Protista ProblemIts a paraphyletic
taxon!!
5
Ecological Roles- Protista

• Can divide the Protists into three categories
• 1. Protozoa- Animal-like, injestive
• 2. Absorptive protists fungus-like
• 3. Photosynthesitc protists- algae

6
The Absorptive Protists A Closer Look
7
The Plasmodial Slime Mold Life Cycle
8
The Dictyostelida- Cellular Slime Molds

• Feeding stage consists of solitary cells
  functioning individually
• When food is low, cells follow chemical trails to
  form an aggregate (pseudoplasmodium)
• Cells in the aggregate maintain their membranes
• Haploid organisms!
• Most have no flagellated stages

9
Dictyostelid Cinema(Cellular Slime Molds)

• Lets Watch!

10
The Dictyostelida- Cellular Slime Molds
http//dictybase.org/Multimedia/development/develo
pment.html
11
Next Thinking About Real Fungi
12
General Characteristics
??
13
The Fungi Structural Organization
14
Sexual Reproduction in Fungi

• In sexually reproducing fungi, the union occurs
  in two stages
• 1. Plasmogamy- fusion of the parents
  cytoplasm
• 2. Karyogamy- fusion of haploid nuclei of
  the two parents
• During the time lag (minutes to centuries!) the
  mycelium is a heterokaryon
• Occasionally the haploid nuclei pair off, two to
  a cell. This mycelium is dikaryotic.

15
Evolution of the Fungi
16
Zygomycete Life Cycle
17
Famous Zygomycota

• The black bread mold, Rhizopus
• The dung fungus, Pilobolus

18
Evolution of the Fungi
19
The Ascomycota (Sac Fungi)

• 30,000 species from marine, freshwater, and
  terrestrial habitats
• Unicellular yeasts to large elaborate morels!
• Many live with algae as lichens, may also form
  mycorrhizae with plants, or between cells in
  leaves!

20
Ascomycetes
21
The Basidiomycota- Club Fungi

• 30,000 fungi including mushrooms, shelf fungi,
  puffballs, and rusts smuts
• Important decomposers (lignin!), also form
  mycorrhiza

22
(No Transcript)
23

• Most vascular plants are associated with
  mycorrhizae.
• Photo ectomycorrhizal fungi (Hebeloma and
  Lactarius species) around the bases of birch
  trees helios.bto.ed.ac.uk

24
Ectomycorrhizae
Ectomycorrhizae occur in almost all tree species
in temperate and boreal forests. Short growing
seasons in these areas limit decomposition and
create nitrogen stress. The fungi release
peptidases (exoenzymes) that break down proteins,
releasing N-containing compounds.
25
Endomycorrhizae
Endomycorrhizae are found in 80 of all plants,
especially in warm/tropical grasslands and
forests. They help supply phosphorus to the
plants.
26
Ecological Adaptations in the Fungi

• Lichens-
• Symbiotic association of millions of algae or
  cyanobacteria within a mesh of fungal hyphae
  (most commonly ascomycetes)