Download Ch 11: Protozoan Groups

CHAPTER 11
Protozoan Groups
I.
Emergence of Eukaryotes
A. Cellular Symbiosis
- 3.5 bya 1st cells (bacteria-like)
- Endosymbiosis Theory of eukaryotic origin,
bacteria feeding:
*aerobic bacteria engulfed to become
Mitochondria
*photosynthetic bacteria engulfed to
become chloroplasts
(evident by DNA, membrane,
ribosomes, binary division)
1
B. Protozoan Contributions
- Unicellular group (some colonial, some
multicellular in short stages of life cycle)
- Specialized organelles (nucleus, etc)
- Division of labor between cells
- Reproduction (asexual & sexual)
- Simple reflexes & instincts
- Varied skeletons (simple endoskeleton or
exoskeleton)
- all types of nutrition (basic enzyme systems)
(autotrophs, heterotrophs, saprobes
- specialized locomotion (some sessile)
(pseudopodia, flagella, cilia)
C. Traditional classification:
1. Flagellates
2. Amebas
3. Sporozoans
4. Ciliates
*new classification drastically different*
- some biologists predict more than 60
monophyletic eukaryotic clades will emerge
2
D. General Features
- over 64,000 species named, ½ are fossils.
- ecologically diverse & widespread
(about 10,000 symbiotic)
- single-celled eukaryotic
- highly specialized organelles
(no tissues or organs)
- require moisture (aquatic or terrestrial)
- mutualistic, commensalistic, parasitic, &
free-living forms
E. Biology: Form & Function
CELLS:
- Eukaryotic (nucleus w/ vesicular appearance
due to lumps of chromatin & nucleoli)
- Unicellular (some have colonial or
multicelled stage)
- Cytoplasm divided into
1. Granular Endoplasm
2. Transparent gel Ectoplasm
3
LOCOMOTOR ORGANELLES
- Cilia and Flagella (both called Undulipodia)
- Axoneme (“9+2” paired microtubule pattern)
move by a “Sliding Microtubule
Hypothesis”
- Pseudopodia (“false foot”)
Lobopodia (endo + ectoplasm)
Filopodia
(ectoplasm only)
EXCRETION & OSMOREGULATION
- Excrete metabolic waste (ammonia) by
simple diffusion through membrane
- Contractile Vacuoles pump H2O using
proton pumps
4
NUTRITION
- Autotrophs & Heterotrophs & Saprobes
- Phagotrophs (heterotroph) ingest food
particles in phagosomes & join w/
lysosomes to digest
- Saprobes (osmotrophs) ingest
soluble food by pinocytosis
- Ciliates have specific locations:
Cytostome
(site of phagocytosis)
Cytopyge/cytoproct (site of expulsion)
REPRODUCTION
A. Asexual
Fission (m/c binary)
Budding (Ciliates)
Multiple fission
(schizogony)
B. Sexual
- not all Protozoans, some exclusively
asexual (haploid)
- some protozoa
undergo gametic
meiosis
5
- some flagellates & sporozoa, 1st division
after fertilization = zygotic meiosis
- some Foraminiferans
alternate
haploid/diploid
- Paramecium use conjugation (exchange
DNA)
C. Encystment/Excystment
- Cyst (dormant form, metabolism shutdown,
covered by resistant cell
wall)
- Cilia & flagella are
reabsorbed; Golgi secretes
wall
- enables resisting cold/hot, pH, etc. but not
sunlight
- environmental cues cause encystment &
excystment
- some protozoa use as stage in regular life
cycle
6
VII. Phylogenetics
- common ancestor of Protozoa & Metazoa
was eukaryotic unicellular ancestor
- separated by locomotion & nutrition (reflect
genetics)
7
VIII. Classification
8
♦ Clade Opisthokonta
(microsporidians & choanoflagellates)
mitochondria, flagella, proteins similar
- choanoflagellates may be sister
taxa to the most recent common
ancestor of animals
♦ Clade Stramenopiles
(heterokonta: brown & yellow algae, diatoms,
opalinids, some heliozoans)
mitochondria, flagella (3-part hair-like
projections)
♦ Clade Viridiplantae
(unicellular/multicellular: green algae, bryophytes,
& vascular plants)
Chloroplasts (chlorophyll pigments)
A. PHYLUM CHLOROPHYTA “Plantlike”
(Chlamydomonas, Volvox)
▪ uni + multicelled
algae
▪ photosynthetic
▪ all have
biflagellated stage
▪ asexual & sexual
reproduction
9
B. PHYLUM EUGLENOZOA
(Euglena, Trypanosoma)
▪ unicellular
▪ photosynthetic (some also
saprobe if no light)
▪ parasitic in some
▪ flagellated stage in all
▪ asexual dominant
C. PHYLUM RETORTAMONADA
2 clades w/ flagella:
1. Phylum Retortamonada
▪ unicellular
▪ commensal & parasitic
▪ lack mitochondria &
golgi bodies
2. Diplomonads
(Giardia)
▪ unicellular
▪ commensal & parasitic (human dysentery)
▪ lack mitochondria but genes in nucleus
10
D. SUPERPHYLUM ALVEOLATA
(Plasmodium, Ciliates, Dinoflagellates)
♦ all have alveoli (membrane-bound sacs)
1. PHYLUM CILIOPHORA
(Ciliates:paramecium, vorticella)
▪ large unicellular group
▪ body surface covered
with cilia
▪ fresh & marine free-living;
few commensal or
parasitic
▪ reproduce sexually &
asexually
2. PHYLUM DINOFLAGELLATA
(Dinoflagellates)
▪ unicellular, colonial, or simple filaments w/
two flagella typically
▪ chromosomes lack or have low levels of
Histones
▪ chromoplasts varied (autotrophs) = primary
producers in marine environments
(planktonic)
▪ mutualistic associations (zooxanthellae –
symbiosis allowing for coral reef fm)
▪ body naked or covered by cellulose plates
or valves
▪ asexual & sexual reproduction
11
3. PHYLUM APICOMPLEXA
(Plasmodium)
▪ unicellular w/ apical complex (unique
organelles) associated in some
developmental stage
▪ only flagellated microgametes in some
▪ cysts often present
▪ parasitic
(cause malaria)
F. AMEBAS
(informal group)
▪ freshwater & marine & moist
▪ some planktonic; all heterotrophs
▪ most asexual (binary fission)
▪ move using pseudopodia
▪ body naked or internal/external
test (skeleton)
1. Rhizopodans
(Amoeba, Difflugia, Entamoeba)
▪ no test; flexible membrane
▪ Entamoeba – animal parasites
12
2. Granuloreticulosa
(Globigerina,
Vertebralina, Forams)
▪ marine protozoans
▪ thin pseudopodia extend out
test
▪ move via thin pseudopodia
(reticulopodia)
▪ Forams – ancient shelled amebas dominated
(largest biomass of any animal group=
benthic ooze covers 1/3 of seafloor, bodies
created chalk/limestone – Egyptian pyramids)
3. Actinopodans
(Heliozoans, Radiolarians)
▪ move by axopod pseudopodia
▪ Heliozoans freshwater amebas
▪ Radiolarians marine test covered amebas
(pelagic) among oldest protozoans
13