KINGDOM PROTISTA• Name means “the very first” (Greek)• Is a “catch all” kingdom for eukaryotes that are not plants, animals or fungi• Divided into categories based on the way they obtain food ---• Plantlike (autotrophs), animal-like (internal digestion), fungus-like (external digestion)• Does not reflect evolutionary relationships.• May one day be separated into >1 kingdom

PROTISTS Eukaryotic - most unicellular. There are a few

multicellular forms. Unlike bacteria, protists have a very complicated

internal structure. Protists can be divided into

plant-like: algae (including seaweed), diatoms animal-like (protozoa)

Flagellated (Giardia), Euglena has characteristics of plant & animal

Ciliated (Paramecia, Euplotes) Ameboid (amoeba species) – use pseudopods or “false feet”

fungus-like (slime molds, etc.) includes many common plant pathogens such as

Phythophthora, cause of the Irish Potato famine

ANIMAL-LIKE PROTISTS Most are free-living. These are

classified according to how they move: amoeba-like, ciliated, or flagellated.

Others are parasitic ; phylum Sporozoa includes Plasmodium which causes malaria. See life cycle page 503.

Amoeba-like protists move by extending cytoplasm into pseudopods, then pulling the rest of the cell along behind. They can surround and engulf their food this way = phagocytosis

Some amoeba-like protists have hard shells. The foraminiferans are covered in calcium carbonate—chalk, which we use on chalk boards.

AMOEBAS IN ACTION

PLANT-LIKE PROTISTS Autotrophs. Most of the

oxygen we breathe came from algal photosynthesis.

Very important commerical uses. Thickener (algin) Most are single-celled,

but a few form large multicellular seaweed species. Some used in food preparation (sushi, etc.)

Some, such as the diatoms, have calcium carbonate (chalk) or silica shells. Important applications

for gardeners

GREEN ALGAE Proposed ancestors of

modern plants. Some algae species

are unicellular (such as Chlamydomonas), some form simple colonies (such as Volvox), and some are relatively complex multicellular organisms (such as Acetabularia).

Green algae are haploid most of their live cycle, with only a very short diploid phase.

ALGAL BLOOMS sudden growth of a

large population of single celled algae

occurs near coastlines, where the algae feed on fertilizer runoff and sewage

Algae blooms deplete the oxygen in the water, killing fish and other organisms.

Some of the algae also secrete toxins. Red tide and Pfiesteria are examples.

MULTICELLULAR ALGAE commonly called seaweed can be classified as red, brown,

and green algae. All have chloroplasts, but the pigments in the chloroplasts vary, giving the different colors.

Some, like kelp, are very large and contain several different types of cells and tissue. These include leaves for photosynthesis, gas-filled bladders for buoyancy, the root-like holdfast, and tubes to transport nutrients throughout the body.

Algae contain the polysaccharide “agar”, which is tasteless and is used to thicken foods such as soft ice cream.

PLANT-LIKE PROTIST: EUGLENA

Has features of a plant … chloroplasts Allows it to make its

own food Has features of an

animal … “eyespot” to detect

light vs dark “flagellum” allows it

to move

DAY 1 SUMMARY Protista is a catch-all

category for eukaryotes that don’t fit anywhere else in the classification system.

They are classified first by how they feed: Plant-like (autotrophs) Animal-like (internal

digestion) Fungi-like (external

digestion) Animal-like are further

divided by how they move. Plant-like (algae) are

classified by the color of their pigments.

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FUNGUS-LIKE PROTISTS Include some of the worst

plant diseases. Phytphthora infestans

causes rot in plants. In the 1840’s, Phytophthora caused the potato blight in Ireland.

Caused crop failures over several years, resulting in much death and emigration.

FUNGUS-LIKE PROTISTS Water molds and slime molds Heterotrophic; many are decomposers

of dead organisms. Unlike fungi, the fungus-like protists

produce motile (moving) cells during part of their life cycle. Also, these protists surround and engulf bacteria as food.

Slime molds live as separate cells most of their lives, feeding on bacteria. When conditions get harsh, they aggregate into a multicellular slug, which migrates to a new location. The slug then forms a fruiting body that generates spores. The spores from the fruiting body are very hardy.

ANIMAL-LIKE PROTISTS: CILIATED Cilia beat in a

synchronized pattern to cause movement. Example: Paramecium

Paramecium is a typical ciliate. It has a gullet to swallow food, and a contractile vacuole to get rid of excess water.

Genetics: the DNA used for sexual reproduction is stored in the small micronucleus. A copy of this information is used to run the cell.

ANIMAL-LIKE PROTISTS: FLAGELLATED

Flagellates have a small number of long flagella, long whiplike hairs that beats to propel the cell.

Some nasty parasites are flagellates, including Giardia lamblia, which causes diarrhea and which is found in most of the surface waters of the US. Another is Trypanosoma brucei, which causes sleeping sickness in Africa. Also Trichmonas vaginalis, a sexually transmitted disease.

ANIMAL-LIKE PROTISTS: PARASITES Sporozoans are animal-

like protists that have part of their life cycle inside the cells of their hosts.

Ex: Plasmodium causes malaria which kills 1-2 million people each year.

Mosquitoes are the vector.

Plasmodium reproduces sexually in mosquito gut and asexually inside the human red blood cells, destroying them as they leave.