Protists

Paraphyletic

A group with a common ancestor but not all its descendants; protists exclude plants, animals, fungi

When do protists usually reproduce sexually?

When conditions deteriorate

Histones

Proteins that DNA wraps around to organize chromosomes

Why algae aren't plants

They don't protect gametes/zygote from desiccation

Why fungus-like protists aren't fungi

No chitin in cell walls; lack flagella

Why animal-like protists aren't animals

No embryonic development

Zooxanthellae

Symbiotic dinoflagellates in coral; give coral sugar, get wastes as fertilizer

Coral bleaching

Corals expel zooxanthellae (e.g., heat stress) and turn white

Archaeplastida

Supergroup: green algae, red algae, land plants

Stramenopila

Supergroup: brown algae, diatoms, water molds

Alveolata

Supergroup: dinoflagellates, ciliates, apicomplexans

Rhizaria

Supergroup: foraminiferans, radiolarians

Discoba (Excavata)

Supergroup: Euglenozoa, kinetoplastids, Metamonada

Amoebozoa

Supergroup: amoeboids, slime molds

Opisthokonta

Supergroup: choanoflagellates, animals, fungi

Discoba key traits

Colorless heterotrophs with unusual mitochondria; many parasitic

African sleeping sickness: cause + vector

Trypanosome; tsetse fly

Chagas disease: cause + vector

Trypanosome; kissing bug

Leishmaniasis vector

Sand fly

Giardia transmission

Cysts in contaminated water

Giardia reservoir host

Beavers

Trichomonas vaginalis

Sexually transmitted protist; common cause of vaginitis

Plants evolved from which algae?

Charophyta (green algae)

Why red algae can live deep (to 200 m)

Red pigment absorbs blue light, which penetrates deepest

Red vs. brown algae water temp

Red = warm; brown = cold

Agar

Gel from red algae; used for culture media, electrophoresis, capsules, dental impressions

Unique fact about brown algae forms

No unicellular or colonial forms; all multicellular

Diatom cell wall

Silica (glass) shell in two halves that fit like a box and lid

Diatomaceous earth

Fossil diatom shells; used for filters, abrasives, soundproofing, natural pesticide

Dinoflagellate flagella

One in a longitudinal groove, one in a transverse groove (makes it spin)

Red tide

Dinoflagellate bloom; toxins in shellfish cause PSP and DSP

ASP (amnesic shellfish poisoning) is caused by

A diatom, not a dinoflagellate

Holozoic

Swallows food whole (ciliates)

Ciliate asexual reproduction

Transverse binary fission

Ciliate two nuclei

Macronucleus = everyday functions; micronucleus = reproduction/gene exchange

Apical complex

Organelles at the tip of apicomplexans used to penetrate host cells

Apicomplexans are…

Nonmotile obligate parasites

Most deadly malaria species

Plasmodium falciparum

Malaria vector

Female Anopheles mosquito

Sporozoite

Malaria stage injected by mosquito; goes to liver

Merozoite

Malaria stage that infects and bursts red blood cells

Why malaria fevers come in cycles

Infected red blood cells burst at the same time

Malaria and anemia

Destroyed red blood cells cause anemia

Malaria treatments

DDT (kills mosquitoes), quinine, ACT; 2 new vaccines

Toxoplasma gondii transmission

Undercooked meat or cat feces (cats get it from rats)

Why toxoplasmosis matters in pregnancy

Can cause birth defects and developmental disability

Pseudopod

Cytoplasm streaming forward to make a 'fake foot' for movement and feeding

Phagocytosis

Engulfing food by surrounding it with pseudopods

Entamoeba histolytica

Colon parasite; causes amoebic dysentery

Naegleria fowleri

Brain-eating amoeba; causes PAM; enters through the nose in warm freshwater

Test (forams/radiolarians)

Hard shell of calcite (CaCO3) or silica

Choanoflagellate structure

Single flagellum surrounded by a collar of microvilli

Sister taxon to animals (Metazoa)

Choanoflagellates

Haploid life cycle

Adult is haploid; zygote is the only diploid stage

Diploid life cycle

Adult is diploid; gametes are the only haploid stage (animals)

Alternation of generations

Multicellular haploid and diploid stages alternate (plants, many algae)

```