Protista

Eukaryotic Kingdoms Animalia –multicellular, motile, ingestive heterotrophs Fungi –multicellular, filamentous, absorptive heterotrophs Plantae –multicellular, embryophytic, photoautotrophs

Eukaryotic Kingdoms Protista –non-animal, non-fungal, non-plant eukaryotes –mostly unicellular –several distinct lineages –modern representatives of earliest eukaryotic lineage(s)

non-plant Figure 28-1 non-animal

Eukaryotic Origins The modern eukaryotic cell type probably arose in stages –a proto-eukaryote arose from a prokaryotic ancestor –the rigid cell surface was replaced with a flexible cell surface increased surface area for exchange of materials with environment pseudo-internal membranes for localized metabolism

early “internal” membranes Figure 28-2

Eukaryotic Origins The modern eukaryotic cell probably arose in stages. –the rigid cell surface was replaced with a flexible cell surface internalized cell membranes formed the nuclear envelope digestive endocytosis increased the capacity for resource uptake

Eukaryotic Origins The modern eukaryotic cell probably arose in stages. –the rigid cell surface was replaced with a flexible cell surface –origin of a cytoskeleton required proteins not encoded in modern Bacteria or Archaea genomes produced the diversity of morphology and motility in unicellular eukaryotic cell types

Eukaryotic Origins The modern eukaryotic cell probably arose in stages. –the origin of organelles by endosymbiosis peroxisomes detoxify products of oxygen metabolism mitochondria provide heterotrophic energy generation using oxygen –a few eukaryotes lack mitochondria

two eukaryotes that lack mitochondria Figure 28-10

Eukaryotic Origins The modern eukaryotic cell probably arose in stages. –origin of organelles by endosymbiosis chloroplasts provide an autotrophic energy/carbon source and generate oxygen

Figure 28-3

Modern Eukaryotes General characters of modern protists –inhabit aquatic or damp sites –exhibit diverse structures –utilize multiple nutritional modes (but fewer than prokaryotes) “protozoans” (a polyphyletic group) –ingestive heterotrophs “algae” (a polyphyletic group) –photoautotrophs

Amoeba proteus Figure 28-4

Modern Eukaryotes General characters of modern protists –locomotion none amoeboid –pseudopods structured by cytoskeletons ciliary –provides fast & precise movement

ciliate diversity Figure 28-15

Modern Eukaryotes General characters of modern protists –locomotion none amoeboid –pseudopods structured by cytoskeletons ciliary –provides fast & precise movement flagellar –whiplike movement pushes/pulls cells

two flagellated protists Figure 28-11

food vacuole in Paramecium Figure 28-6

Modern Eukaryotes General characters of modern protists –various vesicles food vacuole contractile vacuole

contractile vacuoles expel excess water Figure 28-5

calcareous shells of foraminifera Figure 28-7

Modern Eukaryotes General characters of modern protists –diverse cell surfaces plasma membrane only plant-like cell wall calcium carbonate-reinforced shell aggregated sand particles proteinaceous pellicle glassy silicate shells

transparent glassy shells on radiolarians figure 28.8

Endosymbiosis mitochondria and chloroplasts are descended from endosymbiotic proteobacteria and cyanobacteria –2-membrane envelopes –incomplete, but functional, genomes –incapable of extracellular existence

protists in a protist Figure 28-8

Endosymbiosis modern radiolarians –contain endosymbiont protists that are potentially free-living organisms haptophytes, euglenoids, stramenopiles –have chloroplasts with 3 membranes dinoflagellates & cryptomonads –have chloroplasts with 4 membranes

Figure 28-29

Modern Protists Life Cycles –asexual or sexual reproduction –asexual reproduction with genetic recombination Asexual reproduction –binary fission –multiple fission –budding –sporulation

Modern Protists Life Cycles –sexual reproduction gametogenic meiosis [animal-like] sporogenic meiosis [plant-like]

Protist Phylogenies The protists are not a monophyletic group –several monophyletic groups are being defined among the protists rRNA sequencing the significance of morphological, metabolic, life cycle characters is being evaluated

a phylogeny of protist groups Figure 28-9

Diplomonads & Parabasalids oldest known clade(s) of protists lack mitochondria (secondary reduction?) some cause human diseases –Giardia lamblia - a diplomonad –Trichomonas - a parabasilid

Protist Phylogenies The Euglenozoa –unicellular, asexual flagellates –Euglenoids complex cellular organization two unequal anterior flagella +/- chloroplasts (3 membrane envelope) able to grow autotrophically or heterotrophically

photosynthetic euglenoid Figure 28-11

Protist Phylogenies The Euglenozoa –Kinetoplastids have a single large mitochondrion with DNA in a kinetoplast –DNA minicircles & maxicircles »maxicircles encode proteins »minicircles encode editorial guides includes many pathogens –sleeping sickness, leishmaniasis, etc.

parasitic kinetoplastid Figure 28-12

Protist Phylogenies The Alveolata –Dinoflagellates [Pyrrophyta] unicellular, mostly marine, mostly photosynthetic two flagella in perpendicular grooves common endosymbionts esp. in sponges some secondarily heterotrophic parasites some cause red tides many are bioluminescent

Dinoflagellate red tide Figure 28-13

Protist Phylogenies The Alveolata –Apicomplexans obligate parasites complex life cycles –asexual and sexual reproduction –two or more hosts

Figure 28-14

Protist Phylogenies The Alveolata –Ciliates possess short, hair-like cilia mostly heterotrophic highly specialized body form possess two types of nuclei – macronuclei - expression –1-80 micronuclei - recombination

Ciliates Figure 28-15

Paramecium Figure 28-16

Protist Phylogenies The Alveolata –Ciliates Paramecium - genetic recombination without reproduction –conjugation recombines the genomes of two cells –reproduction does not accompany conjugation –non-conjugating clones eventually die

Paramecium conjugation Figure 28-17

Protist Phylogenies The Stramenopiles –protists bearing two unequal flagella, one with tubular hairs (and their descendants) –two photosynthetic groups, one heterotrophic group –the “brown plant” kingdom

Diatoms Figure 28-18

Protist Phylogenies The Stramenopiles –Diatoms [Bacillariophyta] single-celled, non-flagellated produce chrysolaminarin and oils many produce cell walls containing silica asexual reproduction reuses cell walls sexual reproduction creates new walls

diatom reproduction Figure 28-19

Protist Phylogenies The stramenopiles –brown algae [Phaeophyta] multicellular thalli or branched filaments fucoxanthin (carotenoid) pigment some are very large some have tissue and organ differentiation all exhibit alternation of generations –some isomorphic, some heteromorphic

alternation of generations Figure 26-22

Protist Phylogenies The stramenopiles –Oomycetes - water molds, mildews, etc. heterotrophic, coenocytic many are saprobes, some plant parasites cell walls contain cellulose produce flagellated gametes

a water mold Figure 28-23

Protist Phylogenies Rhodophyta - the Red Algae –mostly multicellular, marine –chloroplasts contain phycoerythrin & phycocyanin –produce floridean starch –produce no flagellated motile cells –some are source of agar –ancestors became chloroplasts in brown algae & diatoms

red algae Figure 28-24

Protist Phylogenies Chlorophyta - one of two green algae clades –large, diverse group –varied growth forms unicellular, flagellate colonial filamentous membranous

isomorphic life cycle of Ulva Figure 28-26

Protist Phylogenies Chlorophyta - one clade of green algae –large, diverse group –varied life cycles isogamous or anisogamous isomorphic or heteromorphic haplontic, diplontic or two multicellular generations

heteromorphic haplontic life cycle of Ulothrix Figure 28-27

Protist Phylogenies Charophytes –the other green algae clade smaller, less diverse than chlorophytes sister group (outgroup) to plants

Charophytes, Figure 29-3

Protist Phylogenies Choanoflagellida –flagellated, colonial –cells resemble most common type of sponge cell –may be closest protist relative of animals

Figure 28-28

radiolarian and heliozoan Figure 28-30

Protist Phylogenies Recurring body plans –pseudopodia are produced in several groups amoeboid pseudopodal locomotion arose in several groups actinopods –radiolarians and heliozoans produce thin stiff pseudopods foraminiferans produce thin, branched pseudopods & calcium carbonate shells

Protist Phylogenies Recurring body plans –slime molds three groups share superficial similarities but represent different lineages –acellular forms produce coenocytic sheets –under harsh conditions, sclerotia or sporangia form

Figure 28-31

Protist Phylogenies Recurring body plans –slime molds three groups share superficial similarities but represent different lineages –cellular forms consist of populations of amoeboid cells –under harsh conditions, cells aggregate into a pseudoplasmodium and fruiting body

Figure 28-32

Table 28-1