UBC biol 203

What is a Protist?

Eukaryotes that aren't animals, plants, or fungi

Leeuwenhoek

Discovered the first single cellular organism (cork).

Haeckel

added to biodiversity, protists on top of animals and plants

Whittaker

5 kingdoms, protista & monera (no higher/lower organisms)

Woese

discovered archaea through phylogentic taxonomy of small subunit rRNA

Posterior Probability

probability that the tree is correct

Bootstrap %

confidence for each clade of a tree

Operational Taxonomic units

% similarity

monophyly

share a common ancester

polyphyly

grouped together by common features but not really related (convergent evolution)

Paraphyletic

do not include all descendents of a single common ancester

Phylogeny

Phylogentic tree, hypothesis about evolutionary relationships

How did eukaryote complexity come to occur?

endosymbiosis

Bacteria

2 membrane

peptoglycan membrane, gram negative

flagella (secretion, signalling, sensory)

key to success: metabolism

Eukaryote

plasma membrane

cytoskeleton: tubulin & actin

endomembrane system: transport lipids, protiens, ER, nucleus, golgi, vesicles

Difference in transcription in bacteria and eukaryotes

Bacteria: RNA polymerase binds to -35 -10 box with sigma factor, Polycistronic mRNA (can encode for more than one protiens), operons

Eukaryotes: TATA binding protien binds to TATA box with RNA polymerase and Transcriptional factors. The resulting mRNA has a cap and a poly A tail.

Difference in translation in bacteria and eukaryotes

Bacteria: small subunit with tRNA (fmet) binds to shine dalgarno sequence, then large subunit comes to begin translation.

Eukaryotes: Cap binding protien binds to cap, small subunit with tRNA (met) is joined by large subunit to begin translation. Introns spliced out.

outgroup

more distant to org of interest than they are to each other

Iwabe

used translation elongation factors genome sequence to trace gene to LUCA, thus determining bacteria as the outgroup

Lokiarchaeota

has actin, cytoskeletal genes and endomembrane system which are fundamentals of eukaryotes

Archaea

extreme environment dwellers

have lipid membrane (saturated)

Transcription & translation like eukaryotes at molecular level but simpler

Endosymbiotic theory

Ancestors of mitochondria and plastids was prokaryotes that came to live in a host cell. supported by the fact that mitochondria and chloroplasts have DNA

Archezoa hypothesis

a kingdom proposed for eukaryotes that diverged before origin of mitochondria. Proven false when genetic residue of the mitochondrion is found in amitochondriates (protists lacking mitochondria)

Metamonads (diplomonads)

mostly parasites

tetrakont arrangement

giardia is possible link to mitochondria

mirror image cell (2 cells fused)

Parabasalia

mostly parasites, symbionts

tetrakont

recurrent flagellum

undulating membrane

costa (contracts)

axostyle

Hydrogenosome

Hydrogenosome

no Oxidative phosphorylation

no electron transport

no cristae

no genome

not efficient but anoerobic

possible link to mitochondria

Microsporidia

all parasites (obligate intracellular)

spore (dormant)

Imports ATP

anaerobes

smallest nuclear genome

closely related to fungi (eukaryote)

anchoring disk

polar tube

two nucleus

dipplokaryon

posterior vacuole

Oxymonad

all symbionts

anaerobic

to mitochondira/ organelles

no genes

Fe S cluster by horizontal transfer

LOST (only know eukaryote bc tree)

motile axostyle

pinocytic pore

mitosome/hydrogenosome (only FeS)

Archamoebae

some parasite & free living

branch near mitochondrial origin

evolved from mitochondrial containing ancesters

mitochondria

original gene from alpha-proteobacteria

makes ATP

Translation/Transcription DNA replication

Heme synthesis

FeS cluster

Cristae

Matrix

small and few genome

ATP production mitochondria

glycolysis: 2 ATP

Krebs cycle: 2ATP

Electron transport chain: 26ATP

Endosymbiotic gene transfer

genes present in organelle moved to nucleus but protiens are re-imported

Translocation outer membrane (TOM)

Translocation inner membrane (TIM)

Transit peptide

Plastids

evolved later (not all euk have plastids)

diverse

choloroplast

very closely related to cyanobacteria

photosynthesize and Biosynthesis

TOC & TIC

primary endosymbiosis

cyanobacteria + eukaryote = primary plastid (primary algae)

Green algae

Red algae

Glaucophyte (rare, never secondary endosymbiosis)

secondary endosysmbiosis

primary plastid + some other eukaryote = secondary plastid (secondary algae)

still retain outer membrane

contribute to protist diversity

Chromalveolate hypothesis

endosymbiosis of a red algae gave rise to eukaryotes

Nucleomorphs

contain reduced genone through gene loss and gene transfer

lost in all other algae with plastids of secondary endosymbiosis except Crytomonads and chlorarchinophytes

key evidence for secondary endosysmbiosis

secondary plastid protien secretion

signal peptide and transit peptide

post and co-translational target

directed to ER by Signal recognition particle, then TIC/TOC

transport to more than one cellular compartment

SELMA

symbiont-derived ERAD like machinery

diverts ERAD protein transport capabilites to mediate protein import to the second outmost plastid membrane

ERAD

ER associated degredation system

recycling misfolded proteins from ER

periplastidal compartment

PPC

nuclomorph in the 4 membrane

tertiary endosymbiosis

doesn't contribute to biodiversity

host already a dinoflagellate

non photosynthesis (lost it then re-gained)

symbiont relationship with diatom, haptophytes, cryptophytes

function as two individual cells