Transcript I. Review of Genetics

I. Fungi
A. Characteristics:
Heterotrophs (feed off other organisms)
Many fungi are saprobes (feed off of
dead and decaying organisms)
Some fungi are parasites (feed off of
living organisms; for example,
athlete’s foot)
I. Fungi
B. Anatomy of Fungi
Main body is a mesh (mycelium) made of
many smaller units (hypha).
Hypha is a single cell, surrounded by a cell
wall of chitin.
Mushroom is one example of a fruiting
body, used for reproduction.
I. Fungi
C. Reproduction in Fungi
Most hypae are haploid (n).
When two hyphae join, they unite nuclei
into one cell, which grows into fruiting
body.
Fruiting body (such as mushrooms)
release spores.
After nuclear fusion, the clubshaped structure (now 2n) will
produce and bear haploid spores
at the four tips of the cell.
Diploid Stage
nuclear fusion
meiosis
Haploid Stage
spore (n)
Club-shaped
structures
having two
nuclei (n + n)
form at the
margin of each
gill.
Spores are released.
gills
cap
hypha in
mycelium
Each germinating spore
gives rise to a hypha
that grows and becomes
a branching mycelium.
stalk
hypha
After cytoplasmic fusion, a
“dikaryotic” (n + n) mycelium
gives rise to spore-bearing
bodies (e.g., mushrooms).
cytoplasmic
fusion
Fig. 24.4, p. 395
I. Fungi
D. Fungi Diversity
1. Club Fungi (Basidiomycetes):
Produce common mushrooms.
2. Zygomycetes: Includes bread molds.
3. Sac Fungi (Ascomycetes): Include
organisms such as yeast and truffles.
I. Fungi
E. Value of Fungi
Decompsers in nature
Mycorrhizae: Fungi and Plant grow
together; fungi breaks down material in
soil, releasing nutrients while plant
provides food to fungi.
Lichen: Fungi and Algae growing together.
Fungi breaks down rock or soil, while algae
provides photosynthesis.
dispersal
fragment (cells of
mycobiont and of
photobiont)
cortex (outer
layer of
mycobiont)
photobionts
medulla (inner
layer of loosley
woven hyphae)
cortex
Fig. 24.9a, p. 378
Mycorrhizae
Mycorrhizae