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Microbiology : Protist Unit:

Microbiology : Protist Unit After studying viruses and bacteria, we now turn our attention to PROTISTS. The protists are a kingdom of diverse eukaryotes which are usually unicellular, but can be multicellular. Examples are paramecium, ameba, algae, etc.

Classification of Protists:

Classification of Protists The kingdom protista is divided into several smaller groups (phyla). Some phyla include: Rhizopoda (amoebas) * Apicompleza Chlorophyta (green algae) * Oomycota Rhodophyta ( red algae) Phaeophyta (brown algae) Bacillariophyta (diatoms) Dinoflagellata Euglenophyta Kinetoplastida Ciliophora Acrosiomycota Myxomycota

Characteristics of Protists:

Characteristics of Protists Characteristics of Protists include: Sexual/Asexual reproduction Multicellularity Mitosis and meiosis Flagella and cilia

Nutrition - Protists:

Nutrition - Protists Protists are very diverse in how they acquire food and energy. Protozoa : heterotrophs which feed on other plants and animals. Algae: autotrophic protists, (make their own food)

Protist Phylum - Rhizopoda:

Protist Phylum - Rhizopoda The Rhizopoda phylum of protists have the following characteristics: Move by the use of a pseudopod (false foot) Are heterotrophic Reproduce sexually Live in aquatic environments. Members : amoeba Most are free-living, but some are parasitic. Amebic dysentary (Entamoeba histolytica)

Protist Phylum - Foraminifera:

Protist Phylum - Foraminifera The foraminifera phylum includes marine protists living in sand or attached to other organisms and rocks. (Heterotrophic) Forams have porous shells (tests) which is made up of calcium carbonate (chalk) Forams are heterotrophic, and when they die their shells form limestone.

Protist Phylum – Chlorophyta:

Protist Phylum – Chlorophyta Chlorophyta : green algae Autotrophic Most are freshwater unicellular. Some are multicellular marine organisms. Sexual and asexual reproduction.

Protist Phylum - Rhodophyta:

Protist Phylum - Rhodophyta The Rhodophyta phylum is known as the “red algae”. Red algae are multicellular organisms found in warm ocean waters. They are autotrophs, and are used to make carrageenan and agar. (ice cream)

Protist Phylum - Phaeophyta:

Protist Phylum - Phaeophyta Phylum Phaeophyta is the “brown algae” group. Brown algae are multicellular and found mostly in marine environments. Kelp is an example.

Protist Phylum - Bacillariophyta:

Protist Phylum - Bacillariophyta The phylum Bacillariophyta is known as the diatoms . Unicellular, autotrophic, double shells. Shells are made of silica. Mostly asexual reproduction. Shells form diatomaceous earth.


Flagellates Flagellates are protists that move using flagella (whiplike-tail) The three phyla’s of flagellates we’ll focus on include: Dinoflagellates Euglenoids Kinetoplasts


Dinoflagellates Dinoflagellates (phylum) Unicellular , phototrophic Few in freshwater, most in marine water. Most have two flagella and move like a top. Considered part of “plankton” Some produce toxins (“red tide”) Reproduce asexually

Red Tide:

Red Tide When populations of dinoflagellates “explode” they cause ocean water to appear “red”. These protists are toxic, and the toxin builds up in organisms which feed on them : clams, crustaceans, fish, etc.


Euglenoids The phylum euglenophyta contain freshwater protists. These members include the euglena, and many other species which are photosynthetic and heterotrophic. Some euglenoids have an “eyespot”. Reproduction is asexual.


Kinetoplasts The Kinetoplasts are unicellular heterotrophs. Some live in the guts of termites, and others are found in soils. Many are disease causing – African Sleeping Sickness

Symbiosis : Termites/ Kinetoplasts:

Symbiosis : Termites/ Kinetoplasts Termites can’t digest the cellulose found in wood. Protists which reside in their abdomen have the ability to digest the cellulose, thus the protists ( Trichonympha) allow termites to feed on wood. This is an example of symbiosis : two species living together. Trichonympha


Ciliates The ciliate group of protists contains the phylum : ciliophora. This phylum of protists consists of unicellular heterotrophs with hair like projections (cilia) which allow for movement. The paramecium is a member of this phylum. Paramecium


Paramecium There are several species of paramecium. Paramecium live in freshwater environments and reproduce by mitosis (asexual), as well as conjugation (sexual)

Ciliate Activity:

Ciliate Activity Using a microscope prepare a slide of pond water from a class sample and view the sample for ciliates. Draw a sketch of any ciliates you observe and describe its characteristics. Title this activity “Ciliate Observations” and turn in the box. (5pts)

Slime Molds:

Slime Molds Protist molds are heterotrophs, with limited mobility. They were once thought of as fungi, but they have structural differences. The slime molds include : cellular slime molds ( Acrasiomycota ), Plasmodial slime molds ( Myxomycota , Oomycota , and others.


Acrasiomycota The Acrasiomycota phylum of protists includes single cell slime molds. They are typically found moving through the soil, and eating bacteria. During stress they gather around and form a colony (slug). Reproduction is asexual.


Myxomycota The Myxomycota phylum of protists are known as the plasmodial slime molds. These resemble oozing slime. These molds are a mass of cytoplasm containing many cells.


Oomycota Other slime molds include the phylum Oomycota. This group contains the Oomycetes ( water molds and mildews) Many Oomycetes are pathogenic to plants. This protist causes the Irish potato famine of 1845-1847. They are parasitic or heterotrophic.

Phylum Apicomplexa:

Phylum Apicomplexa The phylum of protists called Apicomplexa are also known as the sporozoans. These protists are parasitic, and form spores during their lives. All sporozoans are parasitic and many cause serious disease to animals.

Apicomplexa : Sporozoans:

Apicomplexa : Sporozoans Sporozoans have complex life-cycles involving sexual and asexual reproduction stages. Sporozoans are transmitted from one host to another by blood feeding insects : mosquitoes, etc.

Common Sporozoans:

Common Sporozoans Plasmodium : sporozoan which causes malaria. Babesia: sporozoan which causes cattle tick fever Cryptosporidium: sporozoan which causes diarrhea and infects humans, birds, deer, cats, and dogs.


Protists/Diseases Many protists cause disease to animals and plants. Some major diseases caused by protists include: African Sleeping Sickness Amebic dynsentary Giardiasis Malaria Toxoplasmosis


Malaria Malaria is a disease which causes an estimated 3 million human deaths a year worldwide. The disease is caused by the protist : Plasmodium , which is a sporozoan commonly found in mosquitoes. The protists are transferred to humans by a mosquito bite. The protists infect liver cells and blood cells.

Malaria :

Malaria * The plasmodium protist has three stages in the human body : The first is the sporozoite stage. This is the infection stage. The second is the merozoite stage, this is the “spreading” of the protists in the body, and the final stage can be the infection of mosquitoes by a human, or the zygote stage.

Treatment for Malaria:

Treatment for Malaria The bark of the conchona tree is used to derive medication for malaria. The bark contains quinine, which seems to kill these protists. Resistance to this treatment however is a major concern. At present scientists are working on a vaccine for malaria, but none is available at this time.

Protist Disease Activity:

Protist Disease Activity Use the internet to briefly research and describe a disease caused by protists. Include the following information : Name of disease and protist which causes it. Symptoms of the disease Treatment for the disease Severity of the disease worldwide Other interesting information .

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