Kingdom Protista

Kingdom Protista

Unique characteristics

·         All eukaryotic unicellular microorganisms

1.   First eukaryotes, well organized nucleus & complex membranous organelles

2.   Unicellular or colonial forms without distinct division of labor 

·         Aquatic and widely distributed all over the world

1.   Locomotion is by pseudopodia, flagella, or cilia

2.   Show mitosis, meiosis and simplest type of sexual reproduction for the first time

3.   Common examples are Amoeba, Para mecium, Euglena, diatoms and dinoflagellates

·         Autotrophic or heterotrophic

1.   Showing varieties of metabolic systems

Classification of Protis

Ciliophora e.g: Paramecium

Apicomplexa e.g: Plasmodium

Rhizopoda e.g: Ciliophora

Animal-like Protista  (Phylum Protozoa)

ta

·         Algae(plant-like)

                             I.        Chlorophyta

                           II.        Phaeophyta

·         Protozoa(animal-like)

                     I.        Euglenophyta

                   II.        Rhizopoda

                 III.        Ciliophora

                 IV.        Apicomplexa

Green Algae (Chlorophyta)

·         This phylum, known as the “green algae”, includes green seaweeds, and the icky mats that float on top of ponds

·         Their green colour comes from chlorophyll and like plants, they use it to make food from sunlight by photosynthesis

·         Some are single-celled (unicellular) and some are made of lots of cells (multicellular)

·         Most live in the water, but might also have seen slimy coatings of green algae on rocks, buildings, or the trunks of trees

·         Vegetative by mitotic cell division in unicellular forms or by fragmentation in filamentous forms : asexual by formation of spores

·         Examples: Chlamydomonas, Volvox, Ulothrix, Spirogyra etc

Brown algae (Phaeophyta)

·         Multicellular, simple, filamentous or plant-like giant forms called kelps (sea weeds)

·         Mostly marine, found in cool shallow water

·         The body is the multicellular thallus

·         Cell wall is made up of two layers.  Inner firm layer is of cellulose while the outer layer is gelatinous containing compounds like algin, fucosin etc

·         Many vacuoles and single large, distinct nucleus, with one or more nucleoli

·         Yellow-brown pigment fucoxanthin a type of xanthophyll is predominant which give golden-brown colour to algae, while other pigments such as chlorophyll-a & chlorophyll-b are also present

·         Laminarin and mannitol are form of soluble carbohydrates for the reserved food

·         Reproductive is vegetative by fragmentation, asexual or sexual

·         Examples: Fucus, Laminaria

Fucus

·         Common “seaweed” found along the rocky coast

·         Some have diploid adults

·         Gametes are produced in the receptacles

Protozoa

Unique characteristic

·         Unicellular organisms

·         Found in fresh water, salt or any moist surroundings

·         May be free living or parasitic

·         The body is covered by plasma membrane and contains one or many nuclei

·         Generally motile. Locomotion is carried out by flagella, cilia or pseudopodia.

·         Most are holotrophic thought some are saprophytic and others parasitic in nutrition

·         Show different organelles : food vacuoles, contractile vacuoles

The protozoans fall into following four phyta :

1)   Rhizopoda :

·         No definite shapes

·         Move by pseudopodia

·         Reproduce by binary fission

·         One nucleus

·         E.g Amoeba

2)   Euglenophyta :

·         Single-celled protest

·         move by one or two whip-like structures called flagella

·         reproduce by longitudinal binary fission

·         possesses chloroplasts like plants

·         E.g Euglena

3)   Ciliophora :

·         Have definite shape

·         Move by cilia

·         Mostly possess two nuclei and two contractile vacuoles

·         Reproduces by simple sexual reproduction called conjugation

·         E.g Paramecium

4)   Apicomplexa :

·         Single-celled

·         Don’t tend to have any way of moving on their own

·         Lots of them live inside other organism

·         E.g Plasmodium: can cause Malaria

Importance of Protista

                                                                     I.        Human health (Plasmodium-malaria)

Ø  Causes of the periodic fevers malaria

                                                                   II.        Roles in biosphere (CO2 fixation)

Ø  Serve as initial food producers

Ø  The first link in the aquatic food chain

Ø  Both fresh water and marine

                                                                 III.        Food sources

Ø  Some of the fresh water algae and sea-weeds are used as vitamin-rich food

Ø  Some red algae are the source of agar jelly, used in the preparation of ice creams and culture media

Ø  Spirulina and Chlorella are used as food supplementary

                                                                 IV.        Eutrophication (algal bloom)

Ø  Process whereby water boddies, such as lakes, estuaries, or slow-moving streams receive excess nutrients that stimulates excessive plant growth (algae, periphyton attached algae and nuisance plants weeds)

Ø  Reduced dissolved oxygen in the water when dead plant material decomposes and cause other organisms to die

Ø  In terms of human values, the odors and unattravtive appearance of algal blooms can detract from the reactional  

                                                                   V.        Red tide (red algae)

Ø  Estuarine or marine algal bloom

Ø  Caused by dinoflagellates of red algae, insufficient numbers, will turn the waters into a deep reddish-brown hue

Ø  Some red tide organisms produce large quantities of neurotoxin that attack the  nervous system and kills fish