Found in Kingdom Protista

Protozoa
Animal like Protists- Zooflagelletes , Sarcodines, Ciliophorans and Spororzoans

Characteristics:

· Eukaryotes

· Found in kingdom Protista

· Most are unicellular

· Heterotrophs that ingest small food particles & digest it inside food vacuoles containing digestive enzymes

· Classified by the way they move (cilia, flagella, pseudopodia...)

· Microscopic in size

· 65,000 identified species with almost half extinct

· Found in freshwater, marine, and moist terrestrial habitats

· Make up part of the zooplankton & serve as food for animals in marine & freshwater systems

· First seen by Leeuwenhoek in 1675

· Many species are free living

· Some species are parasitic living in the bloodstream of their host & cause malaria, amebic dysentery, or giardiasis

· Many serve as food for other organisms in aquatic habitats; called zooplankton

Reproduction:

· All reproduce asexually by binary fission (single protozoan divides into two individuals)

· Some species reproduce by multiple fission producing more than two individuals

· Some species reproduce sexually by conjugation (opposite mating strains join & exchange genetic material)

Adaptations:

· Eyespots in some protozoans can detect changes in light

· Many can form harden covering called cyst when conditions become unfavorable (no water, pH or temperature changes, nutrient deficiency, decreased oxygen supplies…)

· Metabolic activity of protozoans resumes when conditions become favorable again

· Some protozoans can detect & avoid obstacles and harmful chemicals in their environment

· Freshwater protozoa have contractile vacuoles to pump out excess water

Classification:

· Divided into 4 phyla based on their method of movement --- Sarcodina, Ciliophora, Zoomastigina, & Sporozoa

· Found in the kingdom Protista along with algae, slime molds, & water molds

· Sarcodinians move by extending their cytoplasm or pseudopodia (fingerlike projections of the cytoplasm)

· Zooflagellates move by whip like flagella

· Ciliophorans or ciliates move by hair like cilia move

· Sporozoans are nonmotile

Phylum / Common Name / Locomotion / Type of Nutrition / Examples
Sarcodina / sarcodines / pseudopodia / heterotrophic;
some parasitic / Amoeba
Radiolaria
Naegleria
Ciliophora / ciliates / cilia / heterotrophic;
some parasitic / Paramecium
Tetrahymena
Balantidium
Zoomastigina / zooflagellates / flagella / heterotrophic;
some parasitic / Trypanosoma
Leishmania
Giardia
Trichonympha
Sporozoa / sporozoans / (None in Adults) / heterotrophic;
some parasitic / Plasmodium
Toxoplasma

Protozoan Evolution:

· First eukaryotic organism thought to have evolved about 1.5 billion years ago

· Protozoans possible evolved from the 1st eukaryotes by Endosymbiosis

· Endosymbiosis – process where one prokaryote lives inside another becoming dependent upon each other

Phylum Sarcodina:

· Includes hundreds of species of amebas

· Found in freshwater, marine, & moist soil habitats

· Usually reproduce asexually

· Their cytoplasm consists of clear, outer ectoplasm and granular, inner endoplasm

· Move by extending cytoplasm (cytoplasmic streaming)

· Cytoplasm extensions are called “false foot” or pseudopods

· Pseudopods form when the inner cytoplasm or endoplasm pushes the outer cytoplasm or ectoplasm forward to make a blunt, armlike extension

· Ameba move by cytoplasmic streaming to produce pseudopods; process called ameboid movement

· Sarcodines also use their pseudopods for feeding by surrounding & engulfing food particles & other protists; called phagocytosis

· Food is surrounded by a pseudopod & then this part of the cell membrane pinches together forming a food vacuole; called endocytosis

· Cytoplasmic enzymes enter the food vacuole & digest the food

· Undigested food & wastes leave by exocytosis

· Most Sarcodinians have contractile vacuoles to pump out excess water

· Oxygen & carbon dioxide diffuse through the cell membrane

· Sarcodinians may form hard, protective, inactive cysts when conditions become unfavorable (drought, lack of nutrients, heat…)

· React to stimuli such as light

· Some Sarcodinians have hard shells called the test made of silica or calcium carbonate

· Radiolarians found in warm, marine waters have a test made of silica & have sticky pseudopodia to trap food

· Marine Foraminiferans have a test made of calcium carbonate with holes through which pseudopodia extend

· Foraminiferan tests build up and form limestone or chalk (e.g. White Cliffs of Dover)

· Important food source in marine habitats

· Entameba histolytica cysts in untreated water supplies cause amebic dysentery which can be fatal

Phylum Ciliophora:

· Called ciliates because they move by short, hairlike cilia lining the cell membrane

· Cilia may be modified into teeth, paddles, or feet

· Largest group of protozoans

· Most found in freshwater, but some are marine

· Called plankton & serve as a food source

· Form protective cysts to survive unfavorable conditions

· Members include the Paramecium, Vorticella, & Stentor

· Have 2 types of nuclei --- smaller micronuclei & larger macronuclei

· Macronucleus controls asexual reproduction by mitosis

· Can reproduce sexually by conjugation (two paramecia join together & exchange DNA)

· Gases diffuse across cell membrane

Stentor:

· Trumpet shaped protozoan with cilia around the top

· Attaches to feed & then detaches to swim around

Vorticella:

· Cup shaped protozoan with cilia at the top

· Has a coiled stalk to raise & lower the organism

· Can attach to surfaces

Paramecium caudatum:

· Slipper shaped protozoan found in freshwater

· Clear, elastic covering of cell membrane called pellicle

· Pellicle made of protein for protection

· Use cilia to swim & obtain food (algae & bacteria)

· Have 2 contractile vacuoles to pump out excess water

· Cilia sweep food into oral groove where mouth located at the bottom

· Food enters short tube called gullet into food vacuoles where it’s digested

· Wastes leave through anal pore

· Have trichocysts (tiny, toxic darts to help capture prey or anchor to a surface)

· Respond to light & learn by trial & error

· Reproduce asexually by mitosis & sexually by conjugation

Phylum Zoomastigina:

· Called Zooflagellates because have one or more whiplike flagella to move

· Flagella made of bundles of microtubules

· May be freshwater or marine

· Some are parasites such as Trypanosoma that destroy red blood cells & causes fatal African sleeping sickness

· Trichonympha lives symbiotically inside termites & digests cellulose

Phylum Sporozoa:

· Adult sporozoans have no structures for movement

· Form spores

· Most are parasitic using one or more hosts

· Immature sporozoans are called sporozoites & live in body fluids of hosts

· Plasmodium is transmitted by mosquitoes & causes malaria

· Plasmodium sporozoites enter the bloodstream, travel to the liver, divide & form spores called merozoites

· Merozoites attack red blood cells & later form eggs & sperm that fertilize

· New sporozoites migrate to the salivary glands of mosquitoes where they can be passed on to another person

· Malaria can be controlled by controlling mosquito populations & it is treated with a drug called quinine derived from the Cinchona Tree

Algal & Fungal-like Protists
Kingdom Protista
/
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Algal-Like Protists

Characteristics of Algae:

· Plantlike members of the kingdom Protista

· Eukaryotes

· Most unicellular, but some multicellular

· Autotrophic – contain chlorophyll & make food by photosynthesis

· Plankton = communities of organisms, mostly microscopic, that drift passively or swim weakly near the surface of oceans, ponds, and lakes

· Produce oxygen that is returned to the atmosphere

· Range in size from microscopic to seaweeds hundreds of feet in length

· Do not have true roots, stems, nor leaves

· Form gametes (eggs & sperm) in single-celled gametangia (chambers) instead of multicellular gametangia like true plants

· Found in freshwater, marine, and moist soil habitats

· Most have flagella at some time in life cycle

· Algae cells contain organelles called pyrenoids organelles that make & store starch

Structure of Algal Cells:

· The body of algae is called the thallus (1n)

· Algae may be unicellular, colonial, filamentous, or multicellular

· Unicellular algae are single-celled & make up phytoplankton (a population of photosynthetic organisms that begins many aquatic food chains)

· Phytoplankton make much world's carbohydrates & are the major producers of oxygen

Chlamydomonas
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· Colonial algae consist of groups of cells working together

· Some colonial algal cells may specialize for movement, feeding, or reproduction showing for division of labor

Volvox
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· Filamentous algae have slender, rod-shaped thallus arranged in rows joined end-to-end

· Holdfasts are specialized structures in some filamentous algae that attaches the algae so it can grow toward sunlight at the surface

Spirogyra
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· Multicellular algaeoften have a large, complex leaf-like thallus & may have stem-like sections and air bladders

· Macrocystis is among the largest multicellular algae

Reproduction in Unicellular Algae:

Asexual Phase

· Algae absorbs its flagellum

· Haploid algal cell then divides mitotically from 2 to 3 times

· From 4 - 8 haploid flagellated cells called zoospores develop in this parent cell

· Zoospores break out of the parent cell & eventually grow to full size

Sexual Phase

· Haploid cells dividing mitotically to produce either “plus” or “minus” gametes

· A plus gamete and a minus gamete come into contact with one another, shed their cell walls, and fuse to form a diploid zygote

· This resting stage of a zygote is called a zygospore & an withstand bad environmental conditions

· When conditions are bad, the thick wall opens and the living zoospore emerges

Reproduction in Multicellular Algae:

· Oedogonium is a multicellular, filamentous green algae with specialized cells called gametangia that form gametes

· The male gametangia or antheridium makes sperm, & the female gametangia or oogonium makes eggs

· Sperm are released into the water & swim to the egg to fertilize them

· The fertilized egg or zygote is released from the oogonium & forms thick-walled zoospores

· Zoospores undergo meiosis so one cell attaches to the bottom & develops a holdfast while the other zoospores divide & form a filament

· Spirogyra, another filamentous green algae, reproduces by conjugation

· Two filaments align side by side, their adjacent cell walls dissolve, & a conjugation tube forms between them

· Fertilization occurs when a + gamete cell moves through the tube & fuses to the - gamete cell

· Zygote forms a thick walled spore (sporangium) that breaks away from the parent & forms a new filament

Conjugation Tube between Spirogyra

· The leaflike algae Ulva has a sexual reproductive cycle characterized by a pattern called alternation of generations

· Alternation of generations has two distinct multicellular phases- a haploid, gamete-producing phase called a gametophyte and a diploid, spore-producing phase called a sporophyte

· Alternation of Generation also occurs in more complex land plants, but the gametophyte & sporophyte do not resemble each other

Classification:

· Algae are classified into 7 phyla, based on color, type of chlorophyll, form of food-storage substance, and cell wall composition

· All phyla contain chlorophyll a

· All algae live in water or moist areas (ponds, seas, moist soil, ice...)

· Act as producers making food & oxygen

· Many species of algae reproduce sexually and asexually

· Sexual reproduction in algae is often triggered by environmental stress

SEVEN PHYLA OF ALGAE
Phylum / Structure of Thallus / Pigments / Food Storage / Cell Wall composition
Chlorophyta
(Green Algae)
/ Unicellular
Colonial
Filamentous
Multicellular
/ Chlorophyll a & b Carotenoids / Starch / Mainly Cellulose
Phaeophyta
(Brown Algae)
/ Multicellular / Chlorophyll a & c Carotenoids Fucoxanthin
Peridinin / Laminarin / Cellulose
Algin
Rhodophyta
(Red Algae)
/ Multicellular / Chlorophyll a Phycobilins Carotenoid / Starch / Cellulose
CaCO3
Bacillariophyta
(Diatoms)
/ Unicellular Some Colonial / Chlorophyll a & c Carotenoids Xanthophyll / Starch / Pectin
SiO2
Dinoflagellata
(Dinoflagellates)
/ Unicellular / Chlorophyll a & c Carotenoids / Starch / Cellulose
Chrysophyta
(Golden Algae)
/ Unicellular Some Colonial / Chlorophyll a & c
Xanthophyll Carotenoids / Laminarin / Cellulose
Euglenophyta
(Euglenoids)
/ Unicellular / Chlorophyll a & b
Carotenoids Xanthophyll / Paramylon / No Cell Wall Pellicle

Chlorophyta (green Algae):7000 species

· May be unicellular, multicellular, or colonial

· Include Spirogyra, Ulva, & Chlamydomonas

· Contain chlorophyll a & chlorophyll b and carotenoids (orange & yellow pigments) as accessory pigments

· Store food as starch

· Cell walls mainly cellulose, but some marine forms add CaCO3

· Habitat may be freshwater, moist surfaces, or marine environments

· Some have whip-like flagella for movement

· May live symbiotically as lichens

· Thought to have given rise to terrestrial plants

Phaeophyta (brown algae):1500 species

· Contain chlorophyll a & chlorophyll c and fucoxanthin (brown pigment) as accessory pigments

· Most are multicellular growing in cooler marine habitats

· Include kelps & seaweeds

· Largest protists

· Specialized rootlike holdfasts anchor thallus to rocks

· Specialized air bladders keep leaflike blades afloat near surface to get light for photosynthesis

· Stemlike structures are called the stipe and support the blades

· Store food as a carbohydrate called laminarin

· Include Laminaria Fucus

Laminaria / Fucus

· Macrocystis or giant kelp contains algin in its cell walls which is used in cosmetics, some drugs, ice cream, etc.

Rhodophyta (red algae):4000 species