The Protista

Domain Eukarya

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

• Protists are either plant-like, animal-like or fungus-like.

• 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

Spirogyra – filamentous Charophyte

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

Phylogeny of land plants

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

Brown Algae – Kelp beds

Saccharina latissima

Brown Algae – Fucus, air bladders

Diatoms – algae • Single-cell, chlorophyll, carotenoid pigments • Shells of silica, ornate, called a frustule • Freshwater and marine

Imaging Diatoms Greg Parker Photographs Focus-stacking

Diatom Reproduction

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

Red Tides • global phenomenon, becoming more frequent • algae make potent natural toxins

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

Ciliate Protozoa

Malaria - Sporozoans - Apicoplexans

• Non-motile protozoans • Parasitic in animals • Plasmodium => Malaria • Transmitted by

Anopheles mosquitos • Kills 1 million/year

Life cycle of the malaria parasite

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

Leishmaniasis – trypanosome spread by Sandflies

• 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

Plasmodial Slime Mold Life Cycle - Physarum

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

End