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Fig. 27-18e
Thiomargarita namibiensiscontaining sulfur wastes (LM)
0.5
µm
Fig. 27-18f
Fruiting bodies ofChondromyces crocatus, amyxobacterium (SEM)
10 µ
m
Fig. 27-18g
Bdellovibrio bacteriophorusattacking a larger bacterium(colorized TEM)
5 µ
m
B. bacteriophorus
Fig. 27-18h
Helicobacter pylori (colorized TEM)
2 µ
m
Fig. 27-18l
50
µm
Two species of Oscillatoria,filamentous cyanobacteria (LM)
Fig. 27-18m
Streptomyces, the source of many
antibiotics (colorized SEM)
5 µ
m
Fig. 27-18n
1 µ
m
Hundreds of mycoplasmascovering a human fibroblastcell (colorized SEM)
Fig. 27-19
No
bacteriaStrain 1 Strain 2 Strain 3
Soil treatment
Up
take o
f K
by p
lan
ts (
mg
)
0
0.2
0.4
0.6
0.8
1.0
Fig. 27-15
1 µ
m
Fig. 27-20
Fig. 27-22
(a)
(b)
(c)
Fig. 28-01
1 µm
Fig. 28-02-2
Cyanobacterium
Heterotrophiceukaryote
Over the courseof evolution,this membranewas lost.
Red alga
Green alga
Primaryendosymbiosis
Secondaryendosymbiosis
Secondaryendosymbiosis
Secondaryendosymbiosis
Plastid
Dinoflagellates
Apicomplexans
Stramenopiles
Plastid
Euglenids
Chlorarachniophytes
Fig. 28-03g
5 µm
Five Supergroups of Eukaryotes
• It is no longer thought that
amitochondriates (lacking mitochondria)
are the oldest lineage of eukaryotes
• Our understanding of the relationships
among protist groups continues to
change rapidly
• One hypothesis divides all eukaryotes
(including protists) into five supergroups
Fig. 28-03a
Alv
eo
late
sS
tram
en
op
iles
Diplomonads
Parabasalids
Euglenozoans
Dinoflagellates
Apicomplexans
Ciliates
Diatoms
Golden algae
Brown algae
OomycetesE
xcavata
Ch
rom
alv
eo
lata
Rh
izaria
Chlorarachniophytes
Forams
Radiolarians
Arc
ha
ep
lastid
a
Red algae
Chlorophytes
Charophyceans
Land plants
Un
iko
nta
Slime molds
Gymnamoebas
Entamoebas
Nucleariids
Fungi
Choanoflagellates
Animals
Fig. 28-UN1
Kinetoplastids
Euglenids
Diplomonads
Parabasalids
Euglenozoans
Excavata
Chromalveolata
Rhizaria
Archaeplastida
Unikonta
Diplomonads and Parabasalids
• These 2 groups live in anaerobic environments, lack plastids, and have modified mitochondria
• Diplomonads– Have modified mitochondria called mitosomes
– Derive energy anaerobically, for example, by glycolysis
– Have two equal-sized nuclei and multiple flagella
– Are often parasites, for example, Giardia intestinalis
Fig. 28-03g
5 µm
• Parabasalids
– Have reduced mitochondria called
hydrogenosomes that generate some energy
anaerobically
– Include Trichomonas vaginalis, the pathogen
that causes yeast infections in human females
Fig. 28-04
5 µm
Flagella
Undulating membrane
Fig. 28-26
Euglenozoans
• Euglenozoa is a diverse clade that
includes predatory heterotrophs,
photosynthetic autotrophs, and
pathogenic parasites
• The main feature distinguishing them as
a clade is a spiral or crystalline rod of
unknown function inside their flagella
• This clade includes the kinetoplastids and
euglenids
Fig. 28-05
Flagella
Crystalline rod
Ring of microtubules
0.2 µm
Kinetoplastids
• Kinetoplastids have a single mitochondrion with an organized mass of DNA called a kinetoplast
• They include free-living consumers of prokaryotes in freshwater, marine, and moist terrestrial ecosystems
• This group includes Trypanosoma, which causes sleeping sickness in humans
• Another pathogenic trypanosome causes Chagas’ disease
Fig. 28-06
9 µm
Fig. 28-07
Long flagellum
Eyespot
Short flagellum
Contractile vacuole
Nucleus
Chloroplast
Plasma membrane
Light detector
PellicleEuglena (LM) 5 µm
Fig. 28-UN2
Dinoflagellates
Apicomplexans
Ciliates
Diatoms
Golden algae
Brown algae
Oomycetes
Rhizaria
Archaeplastida
Unikonta
Ch
rom
alv
eo
lata
Excavata
Alveolates
Stramenopiles
Fig. 28-08
Flagellum Alveoli
Alveolate
0.2
µm
Dinoflagellates
• Dinoflagellates are a diverse group of
aquatic mixotrophs and heterotrophs
• They are abundant components of both
marine and freshwater phytoplankton
• Each has a characteristic shape that in
many species is reinforced by internal
plates of cellulose
Video: Dinoflagellate
• Two flagella make them spin as they
move through the water
• Dinoflagellate blooms are the cause of
toxic “red tides”
Fig. 28-09
Flagella
3 µ
m
Apicomplexans
• Apicomplexans are parasites of animals,
and some cause serious human diseases
• One end, the apex, contains a complex of
organelles specialized for penetrating a
host
• They have a nonphotosynthetic plastid,
the apicoplast
• Most have sexual and asexual stages
that require two or more different host
species for completion
• The apicomplexan Plasmodium is the
parasite that causes malaria
• Plasmodium requires both mosquitoes
and humans to complete its life cycle
• Approximately 2 million people die each
year from malaria
• Efforts are ongoing to develop vaccines
that target this pathogen
Fig. 28-10-3
Inside human
Liver
Liver cell
Merozoite(n)
Red bloodcells
Gametocytes(n)
Haploid (n)
Diploid (2n)
Key
Merozoite
Apex
Red bloodcell
Zygote
(2n)
FERTILIZATION
Gametes
Inside mosquito
MEIOSIS
Oocyst
Sporozoites
(n)
Ciliates
• Ciliates, a large varied group of protists,
are named for their use of cilia to move
and feed
• They have large macronuclei and small
micronuclei
• The micronuclei function during
conjugation, a sexual process that
produces genetic variation
• Conjugation is separate from
reproduction, which generally occurs by
binary fission
Fig. 28-11a
Contractilevacuole
Cilia
Micronucleus
Macronucleus
Oral groove
Cell mouth
Food vacuoles
(a) Feeding, waste removal, and water balance
50 µm
Fig. 28-11b-2
Compatiblemates
Diploid
micronucleus
MEIOSIS
Haploidmicronucleus
Key
Conjugation
Reproduction(b) Conjugation and reproduction
Diploid
micronucleus
MICRONUCLEAR
FUSION
The originalmacronucleus disintegrates.
Stramenopiles
• The clade Stramenopila includes
several groups of heterotrophs as well
as certain groups of algae
• Most have a “hairy” flagellum paired
with a “smooth” flagellum
Fig. 28-12
Smoothflagellum
Hairyflagellum
5 µm
Diatoms
• Diatoms are unicellular algae with a
unique two-part, glass-like wall of
hydrated silica
• Diatoms usually reproduce asexually, and
occasionally sexually
• Diatoms are a major component of
phytoplankton and are highly diverse
• Fossilized diatom walls compose much of
the sediments known as diatomaceous
earth
Video: Various Diatoms
Video: Diatoms Moving
Fig. 28-03h
50 µm
Fig. 28-13
3 µ
m
Golden Algae
• Golden algae are named for their color,
which results from their yellow and brown
carotenoids
• The cells of golden algae are typically
biflagellated, with both flagella near one
end
• All golden algae are photosynthetic, and
some are also heterotrophic
• Most are unicellular, but some are
colonial
Fig. 28-14
Outer container
Flagellum
Living cell
Brown Algae
• Brown algae are the largest and most
complex algae
• All are multicellular, and most are marine
• Brown algae include many species
commonly called “seaweeds”
• Brown algae have the most complex
multicellular anatomy of all algae
• Giant seaweeds called kelps live in deep
parts of the ocean
• The algal body is plantlike but lacks true
roots, stems, and leaves and is called a
thallus
• The rootlike holdfast anchors the
stemlike stipe, which in turn supports the
leaflike blades
Fig. 28-15
Blade
Stipe
Holdfast
Alternation of Generations
• A variety of life cycles have evolved
among the multicellular algae
• The most complex life cycles include an
alternation of generations, the
alternation of multicellular haploid and
diploid forms
• Heteromorphic generations are
structurally different, while isomorphic
generations look similar
Fig. 28-16-2
10 cm
Haploid (n)
Diploid (2n)
Key
Sporangia
Sporophyte(2n)
Zoospore
MEIOSIS
Female
Gametophytes(n)
EggMale
Sperm
FERTILIZATION
Zygote(2n)
Developingsporophyte
Mature femalegemetophyte(n)
Oomycetes (Water Molds and
Their Relatives)
• Oomycetes include water molds, white
rusts, and downy mildews
• They were once considered fungi based
on morphological studies
• Most oomycetes are decomposers or
parasites
• They have filaments (hyphae) that
facilitate nutrient uptake
• Their ecological impact can be great, as
in Phytophthora infestans causing potato
blight
Fig. 28-17-3
Germ tube
Cyst
Hyphae
ASEXUALREPRODUCTION
Zoospore(2n)
Zoosporangium(2n)
Haploid (n)
Diploid (2n)
Key
Oogonium
Egg nucleus
(n)
Antheridial hypha with sperm nuclei (n)
MEIOSIS
Zygotegermination
SEXUAL
REPRODUCTION
Zygotes(oospores)(2n)
FERTILIZATION
Fig. 28-UN3
Chlorarachniophytes
Foraminiferans
Radiolarians
Excavata
Chromalveolata
Archaeplastida
Unikonta
Rh
izaria
Fig. 28-03l
100 µm
Forams
• Foraminiferans, or forams, are named
for porous, generally multichambered
shells, called tests
• Pseudopodia extend through the pores in
the test
• Foram tests in marine sediments form an
extensive fossil record
Fig. 28-03i
20 µm
Radiolarians
• Marine protists called radiolarians have
tests fused into one delicate piece,
usually made of silica
• Radiolarians use their pseudopodia to
engulf microorganisms through
phagocytosis
• The pseudopodia of radiolarians radiate
from the central body
Fig. 28-18
Pseudopodia
200 µm
Fig. 28-UN4
Chlorophytes
Charophyceans
Red algae
Green algae
Land plants
Excavata
Chromalveolata
RhizariaA
rch
aep
lastid
a
Unikonta
Red Algae
• Red algae are reddish in color due to an
accessory pigment call phycoerythrin,
which masks the green of chlorophyll
• The color varies from greenish-red in
shallow water to dark red or almost black
in deep water
• Red algae are usually multicellular; the
largest are seaweeds
• Red algae are the most abundant large
algae in coastal waters of the tropics
Fig. 28-19Bonnemaisoniahamifera
20 cm
8 mm
Dulse (Palmaria palmata)
Nori. The red alga Porphyra is thesource of a traditional Japanese food. The seaweed is
grown on nets inshallow coastalwaters.
The harvestedseaweed is spreadon bamboo screensto dry.
Paper-thin, glossy sheets of norimake a mineral-rich wrap for rice,seafood, and vegetables in sushi.
Fig. 28-19a
Bonnemaisonia
hamifera
8 mm
Fig. 28-19b
Dulse (Palmaria palmata)
20 cm
Green Algae
• Green algae are named for their grass-
green chloroplasts
• Plants are descended from the green
algae
• The two main groups are chlorophytes
and charophyceans
• Most chlorophytes live in fresh water,
although many are marine
• Other chlorophytes live in damp soil, as
symbionts in lichens, or in snow
Fig. 28-20
Fig. 28-03j
20 µm
50 µm
Fig. 28-21a
(a) Ulva, or sea lettuce
2 cm
Fig. 28-21b
(b) Caulerpa, anintertidal chloro-phyte
Plasmodial Slime Molds
• Many species of plasmodial slime
molds are brightly pigmented, usually
yellow or orange
Video: Plasmodial Slime Mold Streaming
Video: Plasmodial Slime Mold
Fig. 28-24-3
Feedingplasmodium
Matureplasmodium(preparing to fruit)
Youngsporangium
Maturesporangium
Stalk
4 cm
1 mm
Key
Haploid (n)
Diploid (2n)
MEIOSIS
Spores(n)
Germinatingspore
Amoeboid cells(n)
Flagellatedcells(n)
Zygote (2n)
FERTILIZATION
Cellular Slime Molds
• Cellular slime molds form multicellular
aggregates in which cells are separated
by their membranes
• Cells feed individually, but can aggregate
to form a fruiting body
• Dictyostelium discoideum is an
experimental model for studying the
evolution of multicellularity
Fig. 28-25-2
Spores(n)
Emergingamoeba(n)
Solitary amoebas(feeding stage)(n)
Aggregatedamoebas
Migratingaggregate
Fruitingbodies(n)
ASEXUALREPRODUCTION
600 µm
200 µm
Key
Haploid (n)
Diploid (2n)
Amoebas(n)
Zygote(2n)SEXUAL
REPRODUCTION
MEIOSIS
FERTILIZATION