ProtistsBiology 2
Unit 2
General Info of ProtistsVary Considerably Eukaryotes Some single celled, some multicelled Some with cell wall, some without cell wall,
some with “shells”(sectretions or processed sand just beneath plasma membrane
Some with cillia, some with flagella, some with pseudopods
Some heterotrophic, some photoautotrophs Most asexual and sexual, some only
asexual
dinoflagellate
euglenoid
diatom
Red algae
Slime mold
Found in freshwater, marine, and moist terrestrial habitats.
1st seen by Leeuwenhoek in 1675 Some species of protozoan are parasitic Many serve as food for other organisms in
aquatic habitats, called zooplankton
Protists are very diverse, and probably represent several different evolutionary lineages, more distinct from each other than plants, animals, and fungi are.
Protozoan Evolution
Protists are thought to be the 1st eukaryotes, evolving 1.5 billion years ago
Thought to have evolved by endosymbiosis› Process where a prokaryote lives inside
another becoming dependent upon each other
Protists can be divided into plant-like, fungus-like, and animal-like forms.
Animal like protists…AKA protozoans
Classified by the way they move› Cilia, flagella, pseudopodia…
Zoomastigina
Common name is zooflagellates Move via flagella lacks photosynthesis and other plant-
like characteristics Heterotrophic organisms Some may be parasitic
Examples of Zoomastigina
TrypanosomaLeishmaniaGiardiaTrichonympha
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23
4
Sarcodina Commonly called sarcodines Pseudopods Heterotrophic Includes
› Amoeba › Radiolaria› Naegleria
Found in freshwater, marine, and moist soil habitats
Usually reproduce asexually Cytoplasm consists of clear, out
ectoplasm and granular, inner endoplasm
Amoeba move by extending cytoplasm (cytoplasmic streaming) then pulling the rest of the cell along behind.
Pseudopods form when the inner cytoplasm or endoplasm pushes the outer cytoplasm or ectoplasm forward to make a blunt, arm-like extension
Also use pseudopods for feeding by surrounding and engulfing food particles and other protists› phagocytosis
Or food is surrounded by a pseudopod and then this part of the cell membrane pinches together forming a food vacuole› endocytosis
Cytoplasmic enzymes digest the food and undigested waste leaves by exocytosis
Most sarcodines use contractile vacuoles to pump out excess water
Oxygen and CO2 can diffuse through the cell membrane
May form hard, protective inactive cysts, when conditions become unfavorable (drought, heat, lack of nutrients….)
Can react to certain stimuli such as light
Amoebas in Action
Some contain hard shells made of calcium carbonate
Foraminifera – CaCO3 with holes for pseudopodCan build up in ocean and form lime or chalk
Entameba histolytica cysts in untreated water can cause amoebic dysentery
Ciliophora
Commonly called ciliates Move via cilia Heterotrophic Largest group of protozoans Mostly in freshwater, some marine Examples
› Paramecium› Stentor› Vorticella
Cilia may be modified into teeth, paddles, or feet
Form protective cysts to survive unfavorable conditions
Have 2 types of nuclei› Micronuclei› Macronuclei – controls asexual
reproduction by mitosis Can reproduce sexually by conjugation Gases diffuse across cell membrane
Stentor
Trumpet shaped Cilia around top Attaches to feed, then detaches to
swim around
Vorticella
Cup shaped protozoan Cilia at the top Has a coiled stalk to raise and lower
organism Can attach to surfaces Can disappear…
Paramecium
Slipper shaped Clear, elastic covering of cell
membrane called pellicle (made of protein)› Used for protection
Uses cilia to swim and obtain food (algae & bacteria)
…. Cilia sweeps food
into oral grooves where mouth is located at the bottom
Food enters short tube called gullet into food vacuoles where it is digested
Waste leaves through anal pore
Have trichocysts› Toxic darts to help capture prey
Respond to light and learn by trial & error Reproduce asexually by mitosis &
sexually by conjugation
Sporozoa
Commonly called sporozoans No movement in adults Heterotrophic Examples
› Plasmodium› Toxoplasma
Form spores Most are parasitic Immature
sporozoans are called sporozoites and live in body fluids of hosts
Plasmodium sporozites enter the bloodstream, travel to the liver, divide and form spores called merozoites
Merozoites attack rbc’s and later form eggs and sperm that fertilize
New sporozites migrate to the salivary glands of mosquitoes where they can be passed on to another person
Fungus-like Protist Heterotrophic Multi-cellular Unique life cycles with 2 phases Found in moist watery habitats Act as decomposers
› Breaking down dead organic matter Includes:
› Slime molds› Water molds› Chytrids
Slime Molds
Shiny, wet appearance Usually bright colored Life cycle has 2 phases
› Mobile feeding stage› Nonmotile reproductive
stage Make a reproductive
structure or fruiting body that produces spores
Feeding stage of slime mold
plasmodium
Fungal – like in nutrition (absorptive heterotrophs that break down dead organic matter)
Saprophytes or parasites
Saprophytic slime mold pseudoplasmodium
A. Lycogala epidendrumB. Comatricha typhoidesC. Badhamia utriculariaD. Dictydium
Plant-like Protist A.K.A. algae
Eukaryotes Unicellular and multi-cellular Autotrophic - chloroplasts Produce oxygen that is returned to the
atmosphere Huge ranges in sizes No roots, stems, or leaves Some have flagella at some point in life
cycle and contain pyrenoids
Structure of algae
The body of algae is called thallus. Usually haploid. Varies b/w species.› Unicellular› Colonial› Filamentous› Multicellular
…unicellular algae… Single-celled Mostly aquatic Makes up bases of food chain Produces the major portion of oxygen
Chlamydomonas
…colonial algae… Groups of cells working together Allows more efficient movement,
feeding, and reproduction Volvox
…filimentous algae…
Have slender rod-shaped thallus composed of rows of cells joined end to end
May be secured to the ocean floor by holdfasts as it grows toward sunlight
…multicellular algae…
Often have a large, complex leaf-like thallus and may have stem-like section and air bladders
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Sexual P
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Algae absorbs its flagellum Haploid algal cell then divides by mitosis
2-3 times 4-8 haploid flagellated cells called
zoospores develop in parent cell Zoospores break out of the parent cell
and eventually grow to full size
Haploid cells divide by mitosis to produce gametes
2 of these come into contact w/ each other, shed their cell walls, and fuse to form a diploid zygote
Resting stage of zygote is zygospore – can withstand bad environmental conditions
The thick wall opens and living zoospore emerges
Unicellular Reproduction, Chlamaydomonas
Reproduction in multicellular algae
Oedogonium reproduces sexually by producing male & female gametes. Sperm, released into surrounding water, swim 2 the egg.
Conjugation 2 filaments align side
by side, adjacent cell walls dissolve, and a conjugation tube forms between them
Gamete moves through the tube & fuses to another
Zygote forms a thick walled spore called sporangium that breaks away and forms a new filament
Reproduction via alternation of generations…
2 multicellular phases:› Gametophyte - haploid,
gamete producing phase› Sporophyte – diploid, spore
producing phase Equal in appearance &
duration
Classification of Algae
7 phyla:› Color› Type of chlorophyll (in addition to
chlorophyll a)› Form of food storage substance› Cell wall composition
Chlorophyta – green algae
Unicellular, colonial, filamentous, or multicellular
Chlorophyll a & b Carotenoids Starch is source of
food storage Cell wall composed
of cellulose May live
symbiotically as lichens
Thought to give rise to terrestreal plants
Phaeophyta – brown algae
Multicellular Chlorophyll a
& c, carotenoids, fucoxanthin (brwon pig.)
Uses laminarin as food storage
Cell wall made of cellulose and algin
Kelp & seaweed
Brown algae found in cold waters
Rhodophyta – red algae
Multicellular Chorophyll a,
phycobilins, & carotenoid
Uses starch as food storage
Cell wall contains cellulose, CaCO3, & agar3
Bacillariophyta - Diatoms Unicellular, some r colonial Chlorophyll a &c,
carotenoids, and xanthophyll
Stores food as starch Contains pectin and SiO2
in the cell walls No cilia or flagella When they die, form
diatomaceous earth that is abrasive and used in detergents, toothpaste, and fertilizers
Dinoflagellata – (Dinoglaellates) Unicellular
Chlorophyll a & c and carotenoids
Uses starch as food storage
Has cellulose in cell wall; makes armor like plates & spines
…Dinoflagellates…
Major producer in ocean Usually have 2 flagella
that spins and moves Produce a toxic
substance and causes red tides
Some produce light via bioluminescence
Chrysophyta – golden algae
Unicellular and some colonial
Chlorophyll a & c, carotenoids, and xanthophyll
Uses laminarin to store food
Contains cellulose in cell wall
Can produce highly resistant cysts to survive beneath frozen lakes
Euglenophyta - euglenoids
Unicellular chlorophyll a & b, carotenoids,
and xanthophyll Uses paramylon
(polysaccharide) as food storages
Has no cell wall, but has a pellicle (flexible protein covering)
Freshwater, moist soil, and some GI tracts
Can be heterotrophic in the absence of light
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