Domain Eukarya

Kingdom(s?):

Protists

Themes in the Evolution of Protists

Larger Cell Size

• Larger cells make possible the evolution of diverse structuresand functions.

• Compartmentalization increases the available surface area in the interior of cells, easing food & waste transport in & out of the cell.

Paramecium: a unicellular cilliate

Themes in the Evolution of Protists

Locomotion

• Pseudopods

• Protists can be motile by means of cilia or flagella.

2 singlemicrotubules

9 pairedmicrotubules

Flagella Cilia

The structure of eukaryotic flagella and cilia is different than prokaryotic flagella

Themes in the Evolution of Protists

Multicellularity

Volvocales spp. range from unicellular to colonial to multicellular.

Chlamydomonas Gonium Pandorina Volvox

Some protists are clearly multicellular

This green alga, called Coleochaete orbicularis, is multicellular.

Its cells are packed tightly together and are differentiated in form

and function.

Themes in the Evolution of Protists

Meiosis and sexual reproduction

• Meiosis makes eukaryotic sexual reproduction possible.

Meiosis

A1 A2

A1 A2

Parentalgenotype Gametes

A1 or A2

Fertilization

Offspring genotypesA1 A2A1A1

A2A2

Sexual reproduction produces genetic variability

Chlamydomonas

(n)

ASEXUALREPRODUCTION

SEXUALREPRODUCTION

(n)

(n)

(n)

(n)

(2n)

Zygote

Gametes

Maturecell

SYNGAMY

MEIOSIS

(n)

Haploid

Diploid

Some protists may alternate between sexual and asexual reproduction

Giardia lamblia, a diplomonad

Giardiasis is a diarrheal illness sometimes known as “Traveler’s Disease”

Group 2: Euglenozoa

Typically unicellular

Characteristic type of flagella (1-2 flagella)

Autotrophic, heterotrophic, or mixotrophic

Euglena

Group 2: Euglenozoa- Others Trypanosomes- Parasitic

•Trypanosoma brucei- •African Sleeping Sickness•Carried by Tsetse flies

•Trypanosoma cruzii- •Chagas disease•South America

•Leishmania spp. •Worldwide parasites•Transmitted by sandflies

Group 3: Aveolata

Dinoflagellates

Primary producers in coastal areas

Armored cellulose walls

Two whip-like flagella

Gonyaulax – red tide

Group 3: Aveolata

Apicomplexans

All obligate Parasites

• Plasmodium--> malaria

Mass of organelles at one end (penetrate the host)

Spore-forming

Group 3: Aveolata

Ciliates

Cilia- short hair-like flagella used for feeding and moving

Oral groove

Multi-nucleate

Reproduce by fission and conjugation

Paramecium

Stentor

Group 4: Stramenopila

Oomycotes (water molds)

Fungi-like heterotrophs

Most live in fresh water or moist soil where they are important decomposers of plant detritus

Downy mildew

Potato Blight and the Irish

Potato famine

Group 4: Stramenopila Diatoms

Glass cell walls

Major component of marine plankton

Major contributor to marine photosynthesis

Sediment to form diatomaceous earth

Algae: Plant-like Protists Algae are AUTOTROPHIC Protists- they perform

PHOTOSYNTHESIS.

Often called “seaweeds”= brown, red, green algae

Red: chlorophyll a and phycobilins

Brown: chlorophyll aand chlorophyll c

Green: chlorophyll aand chlorophyll b

Algae: Plant-like Protists

Algae are Different from Plants because they LACK Tissue Differentiation and have No True Roots, Leaves or Stems.

Group 5: Rhodophyta

Red Algae

No flagellated stages

Color from phycoerythrin

Often used to make cosmetics, gelatin capsules, agar

Group 6: Chlorophyta

Green Algae

Not monophyletic

Closely related to plants

common ancestor of green algae and plants--> chloroplasts through endosymbiosis of cyanobacteria

mostly freshwater

Unicellular, colonial, multicellular

Group 8: ????

Hodge-podge of organisms with unknown phylogeny

Use pseudopods for moving and feeding

Rhizopods (Amoeba)

Actinopods

Foraminifera Phagocytosis in Amoeba

Amoeba have complex life

cycles