Protist diversity IIProtist diversity II

Level 1 Biological DiversityLevel 1 Biological Diversity

Jim ProvanJim Provan

Phylogeny of eukaryotesPhylogeny of eukaryotes

Diplomonads and ParabasalaDiplomonads and Parabasala

Amitochondriate:Amitochondriate:Originally believe to have Originally believe to have diverged before diverged before acquisition of acquisition of mitochondriamitochondria

Presence of nuclear gene Presence of nuclear gene homologues now suggests homologues now suggests that mitochondria have that mitochondria have been lostbeen lost

DiplomonadsDiplomonads have have multiple flagella and two multiple flagella and two separate nucleiiseparate nucleii

InfectiousInfectious

EuglenozoaEuglenozoa

Contain flagellaContain flagellaTwo main groups:Two main groups:

EuglenoidsEuglenoids::— Paramylon (glucose Paramylon (glucose

polymer) used as a polymer) used as a storage moleculestorage molecule

— Anterior pocket with one Anterior pocket with one or two flagellaor two flagella

KinetoplastidsKinetoplastids::— Contain a single large Contain a single large

mitochondrion and a mitochondrion and a unique organelle unique organelle (kinetoplast)(kinetoplast)

— Symbiotic / pathogenicSymbiotic / pathogenic

AlveolataAlveolata

Encompasses:Encompasses:Photosynthetic flagellates Photosynthetic flagellates ((dinoflagellatesdinoflagellates))

Parasites Parasites ((apicomplexansapicomplexans))

Group that move by cilia Group that move by cilia ((ciliatesciliates))

Have small, membrane-Have small, membrane-bound cavities under bound cavities under cell surfaces (cell surfaces (alveolialveoli))

DinoflagellatesDinoflagellates

Components of phytoplankton – may cause Components of phytoplankton – may cause red red tidestides

Most are unicellular, some are colonialMost are unicellular, some are colonial

Some are photosynthetic symbionts, some are non-Some are photosynthetic symbionts, some are non-photosynthetic parasitesphotosynthetic parasites

Plastids are brownish and contain chlorophylls Plastids are brownish and contain chlorophylls a a and and c c and a mix of carotenoids (including peridinin)and a mix of carotenoids (including peridinin)

Food stored as starchFood stored as starch

Chromosomes lack histones and are always Chromosomes lack histones and are always condensedcondensed

Have no mitotic stagesHave no mitotic stages

ApicomplexansApicomplexans

All parasites of animals:All parasites of animals:Infectious cells called sporozitesInfectious cells called sporozites

Apex of sporozites has organelles for penetrating host Apex of sporozites has organelles for penetrating host cellscells

Life cycles have both sexual and asexual reproduction, Life cycles have both sexual and asexual reproduction, often requiring more than one hostoften requiring more than one host

Several species of Several species of PlasmodiumPlasmodium cause malaria: cause malaria:AnophelesAnopheles mosquitoes serve as intermediate host mosquitoes serve as intermediate host

New, resistant forms of New, resistant forms of PlasmodiumPlasmodium are appearing are appearing

Little success in developing a vaccine:Little success in developing a vaccine:— PlasmodiumPlasmodium spends most of its life cycle in blood or liver cells spends most of its life cycle in blood or liver cells— Has the ability to alter its surface antigensHas the ability to alter its surface antigens

Life history of Life history of PlasmodiumPlasmodium

CiliatesCiliates

Species use cilia to move Species use cilia to move and feedand feed

Most solitary cells in fresh Most solitary cells in fresh waterwaterCilia are short and beat in Cilia are short and beat in synchronysynchronySubmembraneous system Submembraneous system coordinates beatingcoordinates beatingSome species move on leg-Some species move on leg-like like cirricirriOthers have rows of tightly Others have rows of tightly packed cilia which act as packed cilia which act as locomoter membranelleslocomoter membranelles

Among most complex of Among most complex of cellscells

Two types of ciliate nucleiTwo types of ciliate nuclei

Macronucleus:Macronucleus:Is large and has over 50 copies of the genomeIs large and has over 50 copies of the genome

Genes packaged into units, each with hundreds of copies of Genes packaged into units, each with hundreds of copies of just a few genesjust a few genes

Controls everyday functions by synthesising RNAControls everyday functions by synthesising RNA

Necessary for asexual reproduction – macronucleus Necessary for asexual reproduction – macronucleus elongates and splits instead of undergoing mitosiselongates and splits instead of undergoing mitosis

Micronucleus:Micronucleus:Small and present in 1-80 copiesSmall and present in 1-80 copies

Does not function in growth, maintenance or asexual Does not function in growth, maintenance or asexual reproductionreproduction

Functions in the sexual process of Functions in the sexual process of conjugationconjugation

Conjugation and genetic Conjugation and genetic recombination in recombination in ParameciumParamecium

StramenopilesStramenopiles

Includes several heterotrophic groups as well as a Includes several heterotrophic groups as well as a variety of photosynthetic protists (algae):variety of photosynthetic protists (algae):

OomycotaOomycota (water moulds etc.): (water moulds etc.):— HeterotrophicHeterotrophic— Ostensibly similar to fungi but have analogous hyphae, Ostensibly similar to fungi but have analogous hyphae,

cellulose cell walls (as opposed to chitin), prevalent diploid cellulose cell walls (as opposed to chitin), prevalent diploid stage and biflagellated cells (true fungi have no flagellated stage and biflagellated cells (true fungi have no flagellated stages)stages)

Heterokont algae:Heterokont algae:— DiatomsDiatoms have hydrated silica shells and generally reproduce have hydrated silica shells and generally reproduce

asexuallyasexually— ChrysophytesChrysophytes (golden algae) have carotene and xanthophyll (golden algae) have carotene and xanthophyll

accessory pigments and are mostly unicellularaccessory pigments and are mostly unicellular— PhaeophytesPhaeophytes (brown algae) are all multicellular and mostly (brown algae) are all multicellular and mostly

marinemarine

SeaweedsSeaweeds

Have differentiated tissues Have differentiated tissues and organs similar to and organs similar to plants:plants:

Analogous:Analogous:— Holdfast Holdfast root root— Stipe Stipe stem stem— Blade Blade leaf leaf

Commercially important:Commercially important:Food (Food (LaminariaLaminaria and and PorphyraPorphyra))

AgarAgar

ThickenersThickeners

LubricantsLubricants

Alternation of generations in Alternation of generations in algaealgae

Rhodophyta (red algae)Rhodophyta (red algae)

Have no flagellated Have no flagellated stagesstages

Accessory pigment: Accessory pigment: phycoerythrinphycoerythrin

Not always red: Not always red: dependent on depthdependent on depth

Mostly multicellularMostly multicellular

Diverse life cycles but Diverse life cycles but alternation of alternation of generations is commongenerations is common

Chlorophyta (green algae)Chlorophyta (green algae)

Two main groups:Two main groups:ChlorophyceaeChlorophyceae

CharophyceaeCharophyceae

Share a common Share a common ancestor with green ancestor with green plantsplants

Unicellular, colonial or Unicellular, colonial or multicellularmulticellular

Nearly all reproduce Nearly all reproduce sexually by way of sexually by way of biflagellated gametesbiflagellated gametes

Life cycle of Life cycle of ChlamydomonasChlamydomonas

Rhizopods (amoebas)Rhizopods (amoebas)

Simplest unicellular Simplest unicellular protistsprotists

No flagellated stagesNo flagellated stages

PseudopodiaPseudopodia used in used in feeding and movementfeeding and movement

All reproduction is asexualAll reproduction is asexual

Inhabit freshwater, marine Inhabit freshwater, marine and soil habitatsand soil habitats

Most are free living, Most are free living, although some are although some are parasiticparasitic

ActinopodsActinopods

Possess Possess axopodiaaxopodia, , slender form of slender form of pseudopodiapseudopodia

Increase surface area Increase surface area which helps floating and which helps floating and feedingfeedingSome prey may stick to Some prey may stick to axopodia and be axopodia and be phagocytosedphagocytosed

Two main groups:Two main groups:HeliozoansHeliozoans (primarily (primarily freshwater)freshwater)RadiolariansRadiolarians (primarily (primarily marine)marine)

Plasmodial slime moulds Plasmodial slime moulds (Myxomycota)(Myxomycota)

Cellular slime moulds Cellular slime moulds (Acrasiomycota)(Acrasiomycota)