Chapter 26, pages 532-541
Basic Botany-1 4:22-19:26
Five Kindgoms-3 0:00-19:45
II. Characteristics of Kingdom Protista
A. Eukaryotic cells
B. About 200,000 extant and extinct species
C. Structure
1. Size varies from single cells to the giant brown algae that is up to 200 feet long
2. Most are microscopic and single-celled
3. Some are colonial
4. Some are filamentous
5. Some are coenocytic (multinucleated)
D. All
metabolic
processes must be carried on within one cell not different cells as in
multicellular
organisms
E. Methods of obtaining nutrients
1. Autotrophic species contain chlorophyll and photosynthesize like plants
2. Heterotrophic species obtain food by digestion and then absorption of the substrate
3. Some species can be both
autotrophic and heterotrophic depending upon
condiditons
4. Most have aerobic respiration, utilizing mitochondria
F. Living arrangements
1. Some single-celled
2. Some colonial
3. Some filamentous
4. Some symbiotic with other organisms
a.
Mutualism
- one end of the spectrum where both organisms that live together
benefit
b.
Parasitism
- the other end of the spectrum where one living organism absorbs
nourishment from the other at the latter organism's expense
(can be
pathogenic)
5. Most are aquatic or marine and are part of the plankton
6. Terrestrial forms are in damp to wet places
G. Reproduction
1. All reproduce asexually
2. Many reproduce sexually with syngamy (union of gametes)
3. Most do not develop multicellular sex organs
4. None form embryos like higher plants
H. Locomotion
1. Most are motile at some time in their life cycle
2. Methods of movement:
b. Flexing individual cells
d. Many species use two of these motions in the various cells of their life cycle
3. Cilia and flagella
structure: 9 + 2 arrangement of
microtubules
(9 outer doublets
encircling
two single inner microtubules)
III. Division Bacillariophyta - Diatoms
A. Structure
1. Cell wall
a. Pectin with silica embedded in a very regular pattern
b. No cellulose
c. Contains two valves that surround the cell
2. Mostly unicellular
3. Some colonial
4. Pigments
a. Chlorophyll a and c
b. Carotenes
c. Xanthophylls
5. Food reserves
a. Never starch
b. Oil
c. Leucosin - monosaccharide polymer
6. Distribution
a. 75% of the species are aquatic
b. 25% of the species are marine
c. Main component of phytoplankton in both aquatic and marine habitats
B. Classification
1. Order Centrales - circular in morphology
2. Order Pennales - elongate in morphology
C. Life-cycle
a. The visible dominant generation
b. Asexual reproduction of the sporophyte
(1) Nucleus divides
(2) Entire cell increases slightly in diameter
(3) Valves separate
(4) Each
daughter
cell takes one of the valves with open side bounded by the
cell membrane
(5) Each daughter cell grows a new valve on the open side,
inside of the old
valve
(a) One daughter cell is the same size as the parent cell
(b) Other daughter cell is smaller than the parent cell
b. Meiosis in the sporophyte
(1) Meiosis in Order Pennales
(a) Triggered when a
diatom
cell reaches a certain critical minimal size or
when certain
environmental conditions exist
(b) Each diatom cell that undergoes meiosis will produce 4 isogametes within the valves of the parent cell
(c) Each isogamete is haploid
(d) Isogametes are gametes that
look alike, are the same size, and are
motile
(2) Meiosis in Order Centrales
(a) Triggered when a diatom
cell reaches a certain critical minimal size or
when
certain environmental conditions exist
(b) Each diatom cell that
undergoes meiosis will produce either one
egg
or four
sperms
within the
valves
of the parent cell
(c) Each egg and each sperm are haploid
(d) Eggs and sperms are considered
heterogametes
because they look
different
and act different
a. Order Pennales
(1) The valves separate and release the isogametes
(2) The isogametes find each other in the water and
conjugate
(fuse) to form a
zygote
(3) The zygote is diploid and differentiates into an auxospore
(4) The auxospore is the zygote without
valves
that grows to full size and then
differentiates into a mature diatom by
forming two valves
b. Order Centrales
(1) The egg remains within the valves of the parent cell
(2) The valves of the cells producing sperm separate and
the sperm are
released into the water
(3) The sperm find the egg cells by a chemotactic response
(4) The sperm enters the cell with the egg through the
girdle
band to form a
zygote
by
fertilization
(5) The valves of the zygote separate releasing the zygote
into the water which
differentiates into an
auxospore
(6) The auxospore differentiates into a mature diatom by forming two valves
IV. Division Chlorophyta - Green Algae
A. Dominant pigment is chlorophyll
B. Cell characteristics
1. Chloroplasts have unique shapes
2. Nucleus is suspended in the central vacuole by strands of cytoplasm
C. Some unicellular
D. Some filamentous
E. Some colonial
F. Food reserves
1. Starch stored in the pyrenoids
2. Some oil
G. Both aquatic and marine forms
1. Aquatic forms
a. Spirogyra
b. Chlorella
2. Marine forms
a. Ulva
b. Codium
V. Division Rhodophyta - Red Algae
A. Pigments
2. Phycocyanin
B. Distribution
1. Mostly warm water marine habitats, down to 300 feet deep
2. Some (very few, less than 1%) are aquatic
3. Some are parasitic on other red algae
C. Food Reserves:
Floridean Starch, a starch similar to
glycogen
where the
starch
grains
are free in
the cytoplasm
D. Cell Wall
1. Cellulose with pectin embedded
2. Other mucilaginous polysaccharides are embedded in the cell wall
a. Have commercial value
b. Agar is one of them that is gelatin-like in nature
c. Carrageenan is one of them that is used as an emulsifier
E. Thallus
1. Most forms are
essentially
filamentous
where the filaments bind together into
leaf-like
structures
2. Some forms are unicellular or colonial
3. Can be a few inches to six feet long
4. No air bladders
F. Coraline Algae: secretes calcium carbonate
VI. Division Phaeophyta - Brown Algae
A. Pigments
1. Chlorophyll a and c
2. Carotenoids
3. Fucoxanthin - special yellow-brown pigment
B. Distribution
1. Mostly marine in temperate and polar regions
2. Seaweeds of rocky coasts in tidal and shallow subtidal zones to 300 feet deep
3. Largest of all the protists
a. Up to 200 feet long
b. Macrocystis
C. Cell walls
1. Cellulose
2. Algin
a. A mucilaginous polysaccharide embedded in the cell wall
b. Cements cell walls together
c. Used as an emulsifier commercially
D. Food Reserves
1. Laminarin
a. A starch
b. Most abundant of the food reserves
3. Fat droplets
E. Thallus structure
1. Morphology
a. Holdfast - root-like structure that is used for anchorage
b. Stipe - stem portion of the plant
c. Blade - leafy part
d. Bladders
(1) Usually in the blade
(2) Used for buoyancy
e.
Receptacle
- the region right around the
margin
of the blade where the
reproductive structures are located
a. Epidermis
b. Meristoderm
(1) Just under the epidermis
(2) Cells that remain meristematic and contain chlorophyll
(1) Broad region of parenchyma cells
(2) Contain "sieve tube members"
(a) Inner cortex cells
(b) Function like sieve tube members
(c) Structure and function
i) Contains sieve plates
ii) Forms callose
iii) Forms continuous tubes
iv) Transports mannitol
(3) Contains no xylem
F. Example: Fucus and its reproductive cycle
a. The dominant visible generation
b. No asexual reproduction of this generation
c. Meiosis
(1)
Conceptacles
are hollow
bulbous
structures that form within the
receptacle
tissue
(2) Haploid gametes are form inside the conceptacles by meiosis
(a) Megasporangia = female gametangia = oogonia
i) 8
eggs form in each
oogonium
as a result of one
meiosis
and one
mitosis
iii) Each oogonium is on a stalk cell
(b) Microsporangia = male gametangia = antheridia
i) Microsporangium produces 4 microspores
ii) 4 microspores under go 4 mitoses to produce 64 sperm cells
(3) Some
conceptacles
contain both
antheridia
and
oogonia
in the same
conceptacle
(monoecious)
(4) Other conceptacles contain only antheridia and others contain
only oogonia
(dioecious)
(5) Ostiole - opening of the conceptacle
a. Begins when meiosis is complete in the sporophyte generation
b. Asexual reproduction of the gametophyte generation
(1) Oogonia - after the four
megaspores
are formed by
meiosis
they undergo
one
mitotic
division each to make a total of eight
eggs
(2) Antheridia - after the 4
microspores
are formed by
meiosis
they; each
microspore undergoes four
mitotic
divisions to produce a
total of 64 microspores that mature into
64 sperm
cells
(1) Eggs and sperms forced into the open water when sea
water floods the
conceptacle
(2) Eggs and sperms unite in the ocean to form a zygote
(3) The
diploid
zygote develops into a pear-shaped embryo that develops into
a new
thallus
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