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Protist #2•Life cycles•Algae•Dichotomous key
Human life Cycle
Gametes (unicellular) are only haploid cells
Alternation of generations: BOTH diploid and haploid multicellular stages
•Individual haploid spores divide by mitosis (rather than fusing together).•Gametes produced by mitosis fuse to make zygote
(inc. some algae)
Zygote (1 cell) is only diploid cell
Generalized alternation of generation life cycle
2 copies of each chromosome
1 copy of each chromosome
Algae is not a taxon• Algae (informal term) = photosynthetic protist
– 1.5 b.y.o.– Previously organized by color (photosynthetic pigment)
• Red, green, brown, golden– Description based on ecological role as a producer
• Form base of fresh water and marine food chains
If humans had alternation of generations
2n
n
n
n
n
n
2n
n
n
n
n
n
Figure 28.2aDiplomonads
Parabasalids
EuglenozoansE
xcavata
Diatoms
Golden algae
Brown algae
Dinoflagellates
Apicomplexans
Ciliates
Forams
Cercozoans
Radiolarians
“SA
R” clad
e
Stram
eno
piles
Alveo
latesR
hizarian
s
Green
algae
Red algae
Chlorophytes
Charophytes
Land plants
Arch
aeplastid
a
Slime molds
Tubulinids
Entamoebas
Nucleariids
Fungi
Un
ikon
ta
Choanoflagellates
Animals
Am
oeb
ozo
ans
Op
istho
kon
ts
Primary endocytosis of cyanobacteria
Secondary endocytosis of red algae
Figure 28.3
Cyanobacterium
Nucleus
Membranesare representedas dark linesin the cell.
1 2 3
Heterotrophiceukaryote One of these
membraneswas lost inred andgreen algaldescendants.
Red alga
Green alga
Primaryendosymbiosis
Secondaryendosymbiosis
Dinoflagellates
Plastid
Stramenopiles
Plastid
Euglenids
Chlorarachniophytes
Secondaryendosymbiosis
Secondaryendosymbiosis
Figure 28.3a
Cyanobacterium
Nucleus
Membranesare representedas dark linesin the cell.
1 (from euk) 2 (outer cell wall lipid layer—lost)
3 (plasma membrane of bacteria)
Heterotrophiceukaryote One of these
membraneswas lost inred andgreen algaldescendants.
Primary endosymbiosis
Red alga
Green alga
mitochondria
divergence
Figure 28.3b
Red alga
Secondary endosymbiosis
Dinoflagellates
Plastid
Stramenopiles
4 membranes & neucleomorph
Figure 28.2aDiplomonads
Parabasalids
EuglenozoansE
xcavata
Diatoms
Golden algae
Brown algae
Dinoflagellates
Apicomplexans
Ciliates
Forams
Cercozoans
Radiolarians
“SA
R” clad
e
Stram
eno
piles
Alveo
latesR
hizarian
s
Green
algae
Red algae
Chlorophytes
Charophytes
Land plants
Arch
aeplastid
a
Slime molds
Tubulinids
Entamoebas
Nucleariids
Fungi
Un
ikon
ta
Choanoflagellates
Animals
Am
oeb
ozo
ans
Op
istho
kon
ts
Primary endocytosis of cyanobacteria
Secondary endocytosis of red algae
Archaeplastida• Red Algae (rhodophyta)• Green algae (chlorophyta and charophyta)• Land plants• Share a common eukaryotic ancestor that obtained plastid
through endosymbiosis of cyanobacteria• Primary endosymbiosis
Green
algae
Red algae
Chlorophytes
Charophytes
Land plants
Arch
aeplastid
a
Red Algae (rhodophytes)• Mostly marine, mostly multicellular, concentrated in warm tropical
waters• Pigments:
– Chlorophyll– Phycoerythrin (erythr = red)
• Absorbs blue and green light (most penetrating wavelengths)• Shallower water = less phycoerythrin greenish red• Deeper water = more phycoerythrin very dark (almost black) red
• Genus Porphyra = nori• Reproduce asexually and sexually (w/ alt. of generations). • Gametes not flagellated
• agar, carrageenan
Color of pigment = color NOT absorbedAbsorbed = energy to make organic molecules
Green Algae• Mostly freshwater (but some marine and terrestrial)• Range of complexity
– Unicellular, colonial/filamentous, & multicellular
• Chloroplasts to land plants– Chlorophyll
• Most have both sexual and asexual stages.• Mostly by biflagellated gametes• Alternation of generation in some
ChlamydomonasIsogamous = same shape
Poor env.syngamy
Resistant zygospore
spirogyra Conjugation•Sexual reproduction•Different strains•- Strain nucleus moves to + strain and nuclei (isogametes) fuse zygote zygospore
Volvox
• Differentiated cells• Haploid “adult”• Asexual reproduction daughter colonies• Sexual reproduction w/ oogamy• Oogamy
– Small, motile sperm fertilize large non-motile egg
Ulvamulticellular green alga w/ alternation of isomophic generation
SAR AlgaeDiatoms
Golden algae
Brown algae
Dinoflagellates
Apicomplexans
Ciliates
Forams
Cercozoans
Radiolarians
“SA
R” clad
e
Stram
eno
piles
Alveo
latesR
hizarian
s
Brown Algae (phaeophytes)
• All multicellular• Mostly marine
– Common in temperate and cold water
• Can have specialized structures (e..g. holdfast, blades, stipes, etc)
• Important habitat—kelp forests• Food (kombu)• Algin in cell walls• Some alternation of generations
A brown alga life cycle
Golden Algae• Mostly unicellular• Freshwater and marine phytoplankton
– Some mixotrophic• yellow-brown carotenoid pigments• Biflagellated• Can form protective cysts that can survive for decades under poor
conditions
Diatoms• Unicellular• Cell wall (frustule) of silica (silicon dioxide, glass like)
– Protects– two overlapping halves
• Important phytoplankton• Large deposits on the ocean floor and form
sedimentary deposits known as diatomaceous earth• Blooms uptake & sequester large amounts of CO2• Only limited number of species have flagella, most are
planktonic (drifters)
Dinoflagelates• Unicellular, mostly marine• A number have cell walls of cellulose, • two flagella at right angles • Important phytoplankton
– but many species are heterotrophic and many are mixotrophic• Dinoflagellate blooms produce red-tides
– (carotenoid pigments create colors)– toxins
• Symbionts in cnidarians (e.g., corals, jellies, and anemones)• Bioluminesence
1a. Organism is square…………………go to 31b. Organism is not square……………. Go to 2
2a. Organism has stripes……………….. go to 42b. Organism has no stripes……………. Go to 5
3a. Organism has legs ………………… Right walky3b. Organism has no legs……………... Right sitty
4a. Organism has antennae…………….. Roundy feely4b. Organism has no antennae………….go to 6
5a. Organism is happy …………………. Go to 75b. Organism is not happy……………… Plain grumpy
6a. Organism has arms………………….Touchy feely6b. Organism has no arm ………………. Roundy touchy
7a. Organism has 2 or less toes per foot…………. Plain footys7b. Organism has 3 or more toes per foot ………..Plain toesies
Dichotomous Key