Kingdom PROTISTA: What are protists?

Kingdom PROTISTA: What are protists?

Domain Eukarya Eukaryotes have a Nucleus and many organelles! Defined by exclusion –

Cannot be classified as plants, animals or fungi Diverse in body, obtaining food, and movement

How did eukaryotes evolve?

Probably evolved 2 billion years ago Arose through endosymbiosis

One organism lives inside another organism Photosynthetic prokaryote lived inside another

prokaryote chloroplast Aerobic prokaryote lived inside another

prokaryote mitochondrion cDNA and mDNA is similar to Bacteria DNA

How did eukaryotes evolve?

PROTISTA characteristics: body plans

Most are unicellular (example, Paramecium) Some small multicellular colonies (example, Volvox) Some large multicellular colonies (example, kelp)

paramecium volvox kelp

PROTISTA characteristics: obtaining food

Some protists are autotrophs Absorb energy of sun through pigments Make their own food through photosynthesis

light energy + 6H20 + 6CO2 C6 H1206 + 6O2

PROTISTA characteristics: obtaining food

Other protists are heterotrophs Get their food by eating other organisms Release energy by cellular respiration

C6 H1206 + 6O2 6H20 + 6CO2 + energy(ATP)

PROTISTA characteristics: motility

Some move with long, whip-like flagella Others move with shorter cilia Others move by extended pseudopodia

flagella

cilia

pseudopodia

PROTISTA asexual reproduction

Most protists reproduce asexually Binary fission 1 cell divides into 2 equal size cells Multiple fission 1 cell divides into more than 2

How do the offspring compare? Offspring are genetically identical to parent Similarity is created by the process of mitosis

PROTISTA sexual reproduction

Some protists can reproduce sexually Protist conjugation 2 cells join, exchange DNA

How do the offspring compare? Resulting offspring are genetically unique Uniqueness is created by the process of meiosis

Animal-like PROTISTA

Move like animals Heterotrophic: obtain food like animals NOT closely evolutionarily linked to animals

Animal-like PROTISTAPhylum Protozoa

Body plan: unicellular Motility: form pseudopodia

Heterotrophic: absorb food by endocytosis

pseudopod

Animal-like PROTISTAPhylum Protozoa

Animal-like PROTISTAPhylum Ciliophora

Body plan: unicellular

Motility: cilia beat in waves Heterotrophic: cilia sweep food into mouth

cilia

Animal-like PROTISTAPhylum Sarcomastigophora

Body plan: unicellular Motility: one or more flagella

Heterotrophic or parasitic Some cause disease

Trypanosoma causes sleeping sickness Giardia contaminates water

Fly takes up blood and injects trypanosomes

Trypanosomes enter bloodstream

Trypanosomes reproduce by mitosis in blood and spinal fluid

Trypanosomes spread in circulatory and nervous systems

Fly takes up blood and trypanosomes

In fly gut, trypanosomes transform → promastigotes and reproduce by mitosis

Promastigotes leave the fly gut and transform → epimastigotes

Epimastigotes reproduce by mitosis in the salivary gland and transform → trypanosomes

Animal-like PROTISTAPhylum Apicomplexa

Body plan: unicellular Motility: no means of locomotion

All are parasitic Some cause disease

Plasmodium causes malaria Cryptosporidium contaminates water

Mosquito takes up blood and injects sporozoites

Sporozoites invade liver cells

Sporozoites transform → schizonts

Schizonts transform → merozoites.Liver cells rupture

Merozoites invade blood cells

Asexual route: merozoites → schizonts → merozoites → blood cells rupture

Sexual route: some merozoites transform → gametocytes

Mosquito takes in ♂ and ♀ gametocytes

In mosquito stomach, ♂ gamete penetrates ♀ gamete → zygote

Zygote transforms → ookinete

Ookinete invades mosquito gut, transforms → oocyst

Oocysts grow, rupture, release sporozoites

Fungus-like PROTISTA

Often called molds but NOT in Kingdom Fungi Protist cell walls are composed of cellulose Fungi cell walls are composed of chitin

Fungus-like PROTISTAPhylum Myxomycota (plasmodial slime molds)

Body plan: unicellular or multicellular Mobile and stationary life stages

Fungus-like PROTISTAPhylum Myxomycota (plasmodial slime molds)

Mobile stage of life cycle Forms plasmodium: mass of cytoplasm Creeps by amoeboid-like streaming Consumes decaying plants by endocytosis

Fungus-like PROTISTAPhylum Myxomycota (plasmodial slime molds)

Stationary stage of life cycle Reproduces when food is scarce Forms sporophores: spore-bearing structures

Fungus-like PROTISTAPhylum Oomycota (water molds)

Body plan: unicellular and multicellular Motility: flagella

Parasitize fish and many crop plants

Plant-like PROTISTA

Autotrophic: obtain food like plants Lack true roots, stems, and leaves

Plant-like PROTISTAFour basic body plans

1 unicellular known as phytoplankton

2 colonial coordinated group of cells

3 filamentous slender, stringy

4 multicellular often large and complex

Plant-like PROTISTATypes of pigments

chlorophyll phycobilin

fucoxanthin carotenoid

Chlorophyll absorbs red and blue light

Other pigments absorb other wavelengths

√ Efficient photosynthesis

PigmentsChlorophyll – green

Phycobilin – blue-green, yellow, and red

Fucoxanthin – brown and olive-green

Carotenoid – red, orange, and yellow

Plant-like PROTISTAPhylum Chlorophyta (green algae)

Diverse body forms: all four

Diverse habitats: aquatic, moist terrestrial, symbiotic relationships

Pigments: chlorophyll and carotenoids Share common ancestor with plants?

(same pigments and cell wall composition)

Plant-like PROTISTAPhylum Phaeophyta (brown algae)

Body form: multicellular Pigments: chlorophyll and fucoxanthin Habitat: cold, nutrient-rich, rocky coasts

Some of the largest algae known

Plant-like PROTISTAPhylum Rhodophyta (red algae)

Body form: multicellular Pigments: chlorophyll and phycobilin Phycobilin can absorb deep-penetrating light

Rhodophyta can live at great depths

Plant-like PROTISTAPhylum Bacillariophyta (diatoms)

Body form: unicellular or colonial Pigments: chlorophyll, carotenoids, fucoxanthin 2-piece shells have radial or bilateral symmetry

Important role as producers in food web

Plant-like PROTISTAPhylum Dinoflagelleta (dinoflagellates)

Body form: unicellular Pigments: chlorophyll and carotenoids

Some species produce a red tide Turn water reddish during population explosion Red tide toxin can kill large numbers of fish

Plant-like PROTISTAPhylum Chrysophyta (golden algae)

Body form: unicellular and colonial Pigments: chlorophyll, carotenoids, fucoxanthin Resistant cysts allow survival beneath frozen lakes

in winter and dry lakes in summer

Store surplus energy as oil

Plant-like PROTISTAPhylum Euglenophyta (euglenoids)

Body form: unicellular Pigments: chlorophyll, carotenoids

Autotrophic (photosynthetic) and heterotrophic (eyespot and flagellum)