Lab 4 – Protists 2 - How Biology Works

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Protists 2
Laboratory 4
BIOL 171
Lab Study 3A: Amoebozoans
Amoeba proteus
• Pseudopodia – temporary extensions of
amoeboid cells, function in moving and
engulfing food
Slime Molds (Mycetozoa) (again)
• Protists which use spores to reproduce
• Heterotrophic – requires carbon in
organic form, cannot manufacture it’s
own
• Feed using phagocytosis
• Suggests they descended from unicellular
amoeba-like organisms
• Two types: plasmodial and cellular (we
will be observing plasmodial type today)
Physarum (slime mold)
• Plasmodial stage
– vegetative stage that consists of a multinucleate mass of protoplasm
(no cell walls), enormous single cells with thousands of nuclei
– Form when individual flagellated cells swarm together and fuse
– Feeds on bacteria, detritus, fungi, and other slime molds as it creeps
along the surface of moist logs or dead leaves
• Fruiting bodies – sporangia
– Reproductive structures that produce spores
– Life cycle similar to fungi
Slime Mold Life Cycle
Lab Study 4A: Red Algae
(Rhodophyta)
•
•
•
•
Eukaryotic
Photosynthetic
NOT plants
Most are aquatic
What are red algae?
• Simplest is single-celled, but most have a macroscopic, multicellular body
form
• Autotrophic (photosynthetic)– manufactures its own organic nutrients
from inorganic carbon sources
• Contain chlorophyll a and accessory pigments phycocyanin and
phycoerythrin
• Why red? Because these pigments allow red algae to photosynthesize
and live at greater depths than most other algae.
• Not all are red! Many green, black, even blue, depending on the depth in
the ocean they grow
A quick note on pigments – How do they work?
(Why are red algae red?)
1) Photons from the sun excite pigment molecules. 2) These pigments transform the
energy into electrons (using water) and “pump them up” to form NADPH – a
molecule that carries energy to the next step of photosynthesis.
- there will be more on this when we get to plants!
Living Specimens
Porphyridium
Preserved specimens
Porphyra
coralline algae
Chondrus crispus
Porphyra life cycle
both sexual and asexual – alternation of generations!
Coralline algae – “living rock”
• Extremely important role in the ecology of coral
reefs: sea urchins, fish, and mollusks eat them
(herbivore enhancement).
• Create microhabitats that protect invertebrates
from predation.
• Cell walls composed of calcium carbonate – this
allows it to fossilize
• Economic importance: soil conditioners, food
additive for livestock, water filtration, medical
vermifuge (stopped late in 18th century),
preparation of dental bone implants
Economic Uses
• Agar – polysaccharide extracted from the cell wall of red
algae, used to grow bacteria and fungi
• Carrageenan – extracted from red algae cell walls, used to
give the texture of thickness and richness to foods such as
dairy drinks and soups.
• Porphyra (or nori) – seaweed wrappers for sushi, billion-dollar
industry!
Lab Study 4B: Green Algae (Chlorophyta)
• unicellular motile and non-motile, colonial, filamentous, and
multicellular – GREAT DIVERSITY
• Live primarily in freshwater
• Share many characteristics with land plants
– Storage of starch, presence of chlorophylls a and b,
photosynthetic pathways, and organic compounds called
flavonoids
• Most botanists support the hypothesis that plants evolved from
green algae
Living Specimens
Chlamydomonas
Volvox
Pediastrum
Closterium
Pandorina
Volvox
Daughter
colonies
Preserved Specimens
Ulva
Chara
Table 4: Representative Green Algae (pg. 72)
Name
Body Form
Spirogyra
Filamentous
Ulva
Leaf like
Chara
Branched
Chlamydomonas
Pandorina
Unicellular flagellate
Aggregate
Volvox
Colony (flagellate)
Pediastrum
Non-motile colony
Closterium
Non-motile single celled
Characteristics
3A: Amoebozoans
Amoeba proteus
Physarum
Dictyostelium
4A: Rhodophyta: Red Algae
Porphyridium (living)
Polysiphonia (preserved or living)
Chondrus crispus (preserved)
Porphyra (preserved)
Coralline algae (preserved/ set)
Nori
4B: Chlorophyta: Green Algae
Chlamydomonas (living)
Pandorina (living or prepared)
Volvox (living)
Pediastrum (living)
Closterium (living)
Spirogyra (living)
Spirogyra (prepared slides)
Ulva (preserved)
Chara (preserved or live)
Here’s the list for today!
And.... Our own
protist samples!

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