Chapter 28, pages 573-588
Basic Botany-2 0:00-9:35
Five Kingdoms-3 0:00-7:27
I. Characteristics of Kingdom Fungi
A. Lack chlorophyll and thus are heterotrophic
1. Parasite - lives at the expense of another organism, the host
a. Pathogenic - causes the weakening of the host
b.
Obligate - must live as a parasite on a particular host in order to
survive
c. Facultative - prefers a particular host but can still live as a saprophyte
2. Saprophyte - lives off of dead or decaying organic matter
a. Obligate - must live as a saprophyte
b.
Facultative - prefers to live as a saprophyte but can also live as
a
parasite
B. General structure
1. Hyphae - individual filaments
a. Septate - filaments contain cross walls with one nucleus per cell
b.
Nonseptate or coenocytic - filaments that contain no crosswalls
and
thus are multinucleated
c. Septa - name given to cell cross walls in a filament
2. Mycelium - vegetative mass of hyphae or fungus plant body
3. Haustorium - special
absorptive tip of a hypha that penetrates the cell wall into
the center of the cell and absorbs nourishment directly out of
the
cytoplasm
4. Cell walls are composed of cellulose and chitin
C. Types of reproduction
1. Types of asexual reproduction
a. Mitosis - to produce new cells or nuclei
c. Zoospores - motile spores that can be haploid or diploid
(1) Produced in zoosporangia
(2) Sporangiophores are stalks on which sporangia stand
(1) Resistant spores with heavy, thick resistant walls that
form around each cell
and a
septate
hypha
(2) In
coenocytic
filaments
septa
form first and then the resistant walls form as
described above
e. Conidia
(1) Packages of zoospores
(2) How they are formed
(a) End cells of tall long
hyphae
(conidiophores)
round up and separate
from the parent hypha
(b) The round spheres that separate are called conidia
(c) When the conidia find suitable conditions
they
rupture
and release many
zoospores
(d) The zoospores swim for a bit and then settle down and encyst
2. Types of sexual reproduction
a. Heterogamy
b. Isogamy
c. Dikaryon - n + n condition
(1)
Plasmogamy
occurs when the
gametes
unite and
karyogamy
occurs just
before
meiosis
(2) Two haploid gametes unite to produce n = n cells (dikaryon condition)
(3) Dikaryon cells reproduce themselves in large quantities as filaments
(4) In regions where
sporangia
are formed, dikaryon cells undergo
karyogamy
and then
meiosis
immediately thereafter
(1) Homothallic
(a) Self-compatible
(b)
Plasmogamy
and
karyogamy
occur between reproductive structures on
the same
thallus
or within the same strain
(c) Allows self-fertilization
(2) Heterothallic
(a) Self-sterile and other-compatible
(b) Requires the presence of a separate
thallus
or
strain
bearing a
compatible mating
structure before fertilization can occur
(c) Does not allow self-fertilization
II. Classification of Kingdom Fungi
A. Based on:
1. Mycelium structure
2. Spore type
3. Events in the life cycle
B. Four Divisions
1. Oomycophyta - egg fungi - produces oospores and is coenocytic
2. Zygomycophyta - zygote fungi - produces zygospores and is coenocytic
3. Ascomycophyta - sac fungi - produces 8 ascospores in a sac and is septate
4.
Basidiomycophyta
-
club
fungi - produces 4
basidiospores
on a
basidium
and is
septate
5. Deutromycophyta - imperfect fungi
a.
These fungi are present in nature but we don't know enough about their life
cycle
to assign them to the proper division
b.
Thus, we give them a temporary name based on what we do know about
them
so as to be able to refer to them
c. This temporary name we call a form genus
d.
When we have demonstrated the full life cycle of the fungus, it is then named
and assigned to the proper division
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