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Eukarya • Arose about 1.5 BYA.
• Origin of Nucleus? Infolding of plasma membrane
• Internal membrane-bound structures such as mitochondria and chloroplasts are thought to have evolved via bacteria endosymbiosis.
Domain Eukarya
• Much larger and complex than prokaryotic cells
• Domain Eukarya eukaryotic, has nucleus
• DNA arranged in chromosomes.
• Organelles - mitochondria, chloroplasts, and lysosomes
• Unicellular eukaryotes grouped in the Protista, very diverse, may form other kingdoms.
Domain Eukarya
• Protists are mostly unicellular
• Plantae, Fungi and Animalia are mostly multicellular, but
• Plants are autotrophic (produce their own food by photosynthesis) whereas the
• Fungi and animals are heterotrophic (consume other organisms)
Protista – a “Supergroup” • Evolved from the Archaea 1.5 billion years ago
• Polyphyletic group- protista arose from more than one ancestral group
• Represents separate evolutionary lineages
Fig. 21.1
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Ch
rom
alve
ola
tes
Apicomplexans
Dinoflagellates
Ciliates
Brown algae
Golden brown algae
Diatoms
Water molds
Red algae
Chlorophytes
Land plants
Charophytes
Diplomonads
Parabasalids
Euglenids
Kinetoplastids
Animals
Choanoflagellates
Fungi
Nucleariids
Foraminiferans
Radiolarians
Amoeboids
Plasmodial slime molds
Cellular slime molds
Stra
men
op
iles
Alv
eola
tes
Arc
hae
pla
stid
s
Do
mai
n E
uka
rya
Exca
vate
s R
hiz
ari
a
Op
isth
oko
nts
A
mo
eb
ozo
ans
common ancestor of eukaryotes
common ancestor
• Plant-like protists are autotrophs – they contain chloroplasts and make their own food.
• Animal-like and fungus-like protists and are heterotrophs.
• Diverse group – green, red, and brown algae.
• Single celled or multicellular.
• Autotrophs (plants), form the foundation of Earth’s food chains.
• Produce much of Earth’s oxygen.
Plant-like protists – “Algae”
Green Algae – Chlorophytes and Charophytes
• Chlorophyll a and b, like land plants
• Many forms – single celled, filamentous, colonial, sheets
• May have other pigments, orange or red
• Related to land plants
Chlorophytes - Chlamydomonas
• Light-sensitive eyespot • Cup-shaped chloroplast • Pyrenoid – site of starch synthesis
(n)
(n)
haploid (n)
diploid (2n) MEIOSIS
zygospore (2n)
zygote (2n)
FERTILIZATION
Sexual Reproduction
zoospores (n)
gametes pairing
gamete formation
eyespot
nucleus with nucleolus
flagellum
daughter cells (n)
Asexual Reproduction
daughter cell formation
starch granule pyrenoid
chloroplast
adult vegetative cell (n)
Chlamydomonas Life Cycle
Asexual stage Haploid most of the time Sexual stage Diploid zygospore Formed by fusion of two haploid cells Meiosis occurs Haploid zoospores produced
daughter colony vegetative cells
17x
(both): © Manfred Kage/Science Source
Volvox
• Colonial chlorophyte • Adult colony
contains daughter colonies
• Active swimmers
Ulva – Sea Lettuce
• Chlorophyte - Marine • Sheets 2 cells thick • Alternation of Generations like land plants
cell wall
chloroplast
vacuole
nucleus
zygote
cytoplasm
pyrenoid
a. Cell anatomy b. Conjugation 50x
b: © M.I. Walker/Science Source
Spirogyra – filamentous Charophyte
a: © Bob Gibbons/Alamy; b: © Kingsley Stern
main axis
node a. Chara, several individuals b. One individual
branch
Chara – Stonewort
• Charophyte • Freshwater • Calcium carbonate
deposits, crusty feel • Whorls of branches • Reproductive
structures at nodes
The phylogeny of land plants The likely ancestor are charophycean algae • same chloroplast DNA, ribosomal DNA • same membrane structure, peroxisomes, sperm cells
Chara
Red Algae • Warm seas, ribbon-like or filamentous • Pigments red and blue, absorb light at deeper levels • Source of Agar, Carageenan
Brown Algae – Stramenopiles (Phaeophyta) • Pigments chlorophyll a, c, carotenoids give brown color • Cold waters, rocky coasts • Some large multicellular forms, Kelps, Sargassum
Diatoms – algae • Single-cell, chlorophyll, carotenoid pigments • Shells of silica, ornate, called a frustule • Freshwater and marine
When diatoms die, they sink to the bottom of the ocean. The floor may be covered in a layer as deep as 984 feet deep!
Diatomaceous Earth
Water Molds – Fungus-like Protista • Not related to Fungi • Produce zoospores
Diseases - blight of potato, downy mildew of grape vine, sudden oak death, and root and stem rot of soybean
Phytopthora infestans Causes Late Blight of Potato
Phytopthora infestans – Late Blight of Potato
Caused the Irish potato famine in the mid-19th century
dead goldfish
filaments of water mold
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
© Noble Proctor/Science Source
Water Molds – Fungus-like protista Saprolegnia feeding on dead goldfish
Dinoflagellates
• Single celled • Plates of cellulose • 2 whip-like flagella • Light sensitive eyespot • Important plankton,
marine and freshwater • Cause Red Tides, toxic • Some luminescent
Bioluminescent Plankton
Maldives
Karenia brevis the phytoplankton responsible for Florida's red tide
1 million cells of the algae per liter of water—a level at which the organism become highly toxic to fish and shellfish in the area.
• “Protozoans” - animal-like protists (heterotrophs) grouped according to how they move.
• Protozoa means "little animal."
• Behave like tiny animals—specifically, move around, hunt and gather other microbes as food.
Animal-like Protists
• Ciliates form the phylum Ciliophora. • Generally the largest protozoa. • Covered with hair-like cilia • Eat other protozoa and bacteria. • Found in every aquatic habitat.
pellicle
cilia gullet
cilia
anal pore micronucleus trichocyst macronucleus
contractile vacuole
(partially full) food
vacuole oral
groove contractile
vacuole (full)
a. Paramecium
nuclei
b. During conjugation two paramecia first unite at oral areas 100x c. Stentor 125x
food vacuoles
oral groove
contractile vacuole
a: © Carolina Biological Supply/Phototake; b: © Ed Reschke/Photolibrary/Getty Images; c: © Eric Grave/Science Source
Ciliates – animal-like • Paramecium • Stentor
Malaria - Sporozoans - Apicoplexans
• Non-motile protozoans • Parasitic in animals • Plasmodium => Malaria • Transmitted by
Anopheles mosquitos • Kills 1 million/year
Euglena
• Freshwater ponds • Photosynthetic, or
sometimes heterotrophic
• Single-celled • 2 flagella, long, short • Flexible skin, the
pellicle, allows them to change shapes
• Pyrenoid - starch
Diplomonad - Giardia
• 2 nuclei • 2 sets of flagella • Lack mitochondria • Giardia – lives in
digestive tract of variety of mammals (beaver)
• Infects hikers drinking unclean water
• Violent diarrhea, upset stomach
Naegleria fowleri – the brain-eating Amoeba
• Found in warm ponds • Enters through nose,
spreads to brain • Severe brain
infection, fatal 97% • Mostly in South, but
may be spreading due to climate warming
Trypanosomes
• Parasitic protozoans • Distinctive kinetoplasts,
large masses of DNA in mitochondria
• Passed to humans by insect bites African Sleeping Sickness Chagas Disease Leishmaniasis
flagellum
1,750x
b. undulating membrane
a.
red blood cell
trypanosome
a: © Eye of Science/Science Source
Trypanosoma brucei
Tsetse flies live
in moist savanna and
woodlands, regions with
>500 mm of rain a year.
Tsetse flies carry a
parasite that can infect
livestock and people with
trypanosomiasis
(sleeping sickness).
Tsetse fly modern
distribution
Trypansoma brucei – Sleeping Sickness
• Amoebae live in water or moist places.
• They have a cell membrane but no cell wall.
• Ooze along by means of pseudopodia (false feet) engulfing food as they go
Fig. 21.19
cytoplasm
pseudopod
food vacuole
nucleus
nucleolus
plasma membrane
contractile vacuole
mitochondrion
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
Plasmodial Slime Molds
• Feed on dead plant material
• Lack cell walls • Plasmodium – mobile
amoeboid mass • Creeps along forest floor • Under certain conditions
develops sporangia, release haploid cells that fuse to form zygote
Cellular Slime Molds • Exist as individual cells • Come together to form pseudoplasmodium • Gives rise to fruiting body
b. Radiolarian tests SEM 150x
160x
a. Foraminiferan, Globigerina, and the White Cliffs of Dover, England
a(cliffs): © Stockbyte/Getty RF; a(Globigerina): © NHPA/SuperStock; b(tests): © Eye of Science/Science Source
Foraminiferans and Radiolarians • Pseudopodia • Shells, tests, made up of calcium carbonate • Abundant in oceans, settle to bottom • Sediments thousands of feet deep, used as index fossils
Protista Videos Life in a Drop of Water https://www.youtube.com/watch?v=_cpBK2t0Yeo Euglena https://www.youtube.com/watch?v=NepvSAJhlkw Paramecium https://www.youtube.com/watch?v=WFpBRfLtbIo Amoeba Clip 3 https://www.youtube.com/watch?v=iRQTY_9Yekc Volvox Dances https://www.youtube.com/watch?v=w8O4OolGcPg Slime mold time lapse https://www.youtube.com/watch?v=B79Z56vl02A Amoeba eats two paramecia (Amoeba's lunch) https://www.youtube.com/watch?v=pvOz4V699gk