L6 Protists

which kingdoms/domains of life are comprised of eukaryotic cells?

protists

characteristics of eukaryotic cells

• true nucleus

• internal membrane

• membrane bound organelles

• organized in complex manner

what is a plastid?

organelle (chloroplasts)

• have different pigments

which kind of biota likely served as the progenitor of plastids?

cyanobacterium

endosymbiosis caused an….

heterotrophic eukaryote to engulf a cyanobacterium

what likely happened during secondary endosymbiosis?

diverged lineage into red algae and green algae and some were engulfed by other eukaryotes

what does (the kingdom protista being) polyphyletic mean?

protists were derived from more than one ancestral stock
- many protist are more closely related to other eukaryotes than other protists

life cycle of Giardia intestinalis?

cyst stage → cyst undergo excystation to trophozoites (to nourish itself in small intestine → goes through binary fission → trophozoites undergo encystation to cysts in colon → diarrhea → if chronic infection: maladsoprtion

how do humans become infested from Giardia

ingesting via oral route

encystation (where in Giardia)

form a cyst
- occur in colon

excystation (where in Giardia)

break down cyst
- occur in small intestine

G intestinalis get its nutrients from…

small intestine

how does Giardia reproduce?

binary fission

acute vs chronic infection — Giardia

• acute infection begins with diarrhea [lasting 1-14 days]

• chronic infection leads to maladsorption

life cycle of trichomonas vaginalis

1. trophozoite in vaginal + prostatic secretions and urine

2. multiples by longitudinal binary fission

3. trophozoite in vagina or office of urethra

4. sexual intercourse

how do humans become infested from Trichonmonas vaginalis

sex

• it infects mucous linings of human reproductive and urinary systems

Trichomonas vaginalis only exists in what stage?

morphological stage, a trophozoite and cannot encyst

T. vaginalis gets its nutrients from…

flagellar adhesion proteins and accquired bacter genes it uses to live/feed off of vaginal lining

what does T. vaginalis cause?

STD: trichomoniasis or Trich
- most curable human STD

how many flagella do most euglenozoans posses?

2

Which flagellar characteristic allows biologists to discern euglenozoans from other protists

crystalline rod in one of their flagella

many euglenozoans have….

kinetoplastids which are single, large mitochondrion

what is a pellicle?

spiral protein/microtubule network beneath plasma membrane that permits shape changes and movement

which nutritional mode characterizes Euglena?

phagocytic heterotrophs or mixotrophs

purpose of light detector in Euglena

for +phototaxis / eye spot (a pigment) shields the detector from odd light angles

what does trypanosoma casue?

trypanosomiasis

south america vs african trypanosoma

• souther americans tend to get it from vector = kissing bug (Chagas disease)

• african vector is Tsetse fly (Sleeping sickness)

trypanosoma is most common in…

eastern hemisphere due to humidity

• found recently in tanzania

how is trypanosoma passed?

via saliva of former and feces of latter

what is a vector

animal that transmits pathogen to human

dinoflagellates

whirling, flagellated cells

• 2 spiral flagella reside within a groove that circumscribes entire cell (top+bottom are reinforced with cellulose)

where do dinoflagellates live?

• plankton of marine

• fresh waters in photic zone

nutritional mode of dinoflagellates

(half) photoautotrophic and mixotrophic

Karenia brevis secrete brevetoxin that

• bind voltage-gated Na+ channels disrupting neural impulses killing aquatic life and sickening humans who eat contaminated seafood

• non toxic blooms may kill aquatic life in shallows from dead biomass causing BOD pollution

  • not all dinoflagellates kill by toxins and not all kill

BOD

biological oxygen demand

• high BOD indicates polluted water (from dead biomass)

plasmodium life cycle

complex LFC involving Anopeles mosquitoes and Homo hosts

how does human host become infected from plasmodium

via Anopheles saliva

plasmodium infection causes….

malaria

sporozoite

form via meiosis/injects from mosquito (spit)

• infect liver cells

merozoite

transformed sporozoites that infect liver cells

gametocyte

(n) produces gametes

gamete

(n) produced from gametocytes

(plasmodium) in Anopheles….

• zygote (2n) forms an oocyst in which sporozoites (n) form via meiosis

• injected into Homo via Anapheles saliva

(plasmodium) in Homo sporozoites…

• infects liver cells, transform into merozoites (n) with apical complex to invade RBCs to cloak themselves

• some transform into gametocytes (n) that produce gametes (n) once drawn into another Anopheles

apical complex

helps host penetration and invasion

• invades RNCs to cloak themselves

paramecium caudatum is a

cilate alveolate (2 kinds of nucleus)

are paramecium caudatum freeliving or parasitic?

freeliving

• live in fresh water environments

micronucleus

(germinal)

• exchanged during conjugation providing a mechanism for horizontal gene exchange

macronucleus

(somatic)

• contains entire genome and is expressed micronuclei eventually form macronuclei

cilia is used to….

to move and feed

contractile vacuoles

evacuate water from hypotonic environs

hypotonic

solute more concentrated inside organism

diatoms

unicellular algae encased in glass frustule (SiO2) embedded within an organic matrix

• often 2 halves open like petri dish

SiO2 is..

glass

most diatoms have

yellow/brown chloroplasts and contribute significantly to aquatic food webs as primary producers

diatomaceous earth

used to clean filters and kill bugs

postelsia

brown alga

laminaria

brown alga referred to as kelp

brown algae are…

multicellular photoautotrophs

• use chlorophyll a + c and fucoxanthin (brown pigment)

• can grow up to 60 m

pigment is used to carry out photosynthesis in

filtered blue light of water

3 main parts of typical brown alga

• holdfast: attach to substrate

• stripe: flexibility

• blades: carries out photosynthesis

gas float

used for buoyancy/allow it to float

rhizarian is an….

amoebae-like protists

• fine pseudopodia used to swim, feed and form a net for test formation

pseudopodia

extensions of plasma membrane

rhizarians we looked at:

• foraminiferans

• radiolarians

foraminiferans form test using

CaCO3 (calcium carbonate)

radiolarians form tests by secreting

SiO2 (silica)

test

foram shell

as ocean pH decreases it becomes more…

difficult to form tests

• as ATM [O2] increases, pH ocean decreases (more difficult to make test)

rhodophytes

multicellular red algae that posses pigment called phycoerythirn

phycoerythrin is a…

pigment that aids in absorbing light at depth

• poses red color because light rays reaching them at depths is less

porphyra is used to make

nori (seaweed)

chlorophyte

green algae

green algae

• inhabit freshwater

• have single cup-shaped chloroplasts

• contain bi flagellated gametes

Chlamydomonas spp…

• unicellular

• resemble gametes of multicellular species

C. nivalis live in…

slow fields / glaciers

volvox

bi-flagellated with single cup shaped chloroplasts but they colonize into spherical colonies

ulva

edible form (think Nori) / uses holdfast in its intertidal habitat

Caulerpa thalli

lack cross walls subdivide filaments

Caulerpa taxifolia have become invasive in…

Mediterranean Sea and San Francisco Bay due to growing a mat across sea floor

• disrupts food chain

Charophytes are sister taxa to

Land plants

slime molds used to be classified as fungi due to

their nets resembling fungi mycelia and because they produce spores

spores are

reproductive spots

spores are haploid or diploid?

(n)

slime mold zygote (haploid/diploid)

(2n)

2 stages in slime mold LFC:

• plasmodial

• cellular slime mold

plasmodial slime mold zygote (2n) undegoes…

repeated mitosis without cytokinesis and grows into a multi-nucleated plasmodium that feeds on detritus

• matures into a net-like form and then sporulates formina spores (n)

cellular slime molds (Dictyostelium discoideum) feeding stage is

solitary amoebae (n), when food dries up they behave as multicellular pseduoplasmodium that can disperse when no food is sporulates (amoebae climb the fruiting bodies)

in cellular slime molds, haploid spores disperse by….

physical forces farther than pseudoplasmodium (new amoebae (n) emerge)

two amoebae (n) can fuse to form a zygote (2n) and as it….

engulfs other amoebae, it undergoes meiosis followed by several rounds of mitosis, it ruptures releasing several amoebae (n)

gymnamoebas like all unikontid amoebas have

“plump” pseudopodia used to move and feed

most gymnamoebas species are free living

• heterotrophs that feed on prokaryotes and other protists

• some are detrivitores living in and feed off duff layer of forest floors

• most inhabit freshwater

entamoebas are

parasites of vertebrates

• 6 species infect humans but only one is pathogenic

Entamoeba histolytica and Trophozoites cause

human disease

amebiasis

parasitic infection of colon with amoeba Entamoeba histolytica

• consequence of dehydration

• ingested

trophozoites encyst in

colon

how to reduce/eliminate infection by portist:

• personal hygiene

• safe water/food

• medical treatments

Phytophora ramorum is an

oomycetic protist

• causes Sudden Oak Death Syndrome

  • trees: Oaks, tanoaks, and bay laurels

oomycetic protists kills trees by

causing bark cankers that disrupt xylem/pholem or weaken tree for 2* infection by fungi, bark beetles, etc

roles protists serve in marine food web

• producers

• photosynthesis