KINGDOM PROTISTABiology 112

Kingdom Protista• All are simple eukaryotes (cells with

nuclei).• Protists are an unusual group of

organisms that were put together because they don't really seem to belong to any other Kingdom

• Mostly microscopic• Live in moist surroundings.• Most unicellular *(amoeba);

multicellular (seaweed/kelp)• Autotrophs, heterotrophs, or both.• Some can move - others cannot.

3 categories of Protists:

• Animal-like

•Plant-like•Fungus – like

Animal-like Protists (Protozoans)

*Unicellular heterotrophs*Four groups based on movement: those with pseudopods, cilia, flagella, and the non motile sporozoans.

Protozoans with Pseudopods Ex: Amoeba

• 1. Phylum Sarcodine• Pseudopods also

called ‘False Feet’ • Cell membrane pulls

in one direction & the cytoplasm folds into the bulge.

http://www.youtube.com/watch?v=7pR7TNzJ_pA

Amoeba

Mimivirus: infects a species of amoeba and is the largest known virus ever discovered.

Mimivirus enters amoeba cells by phagocytosis

Protozoans with cilia

EX: Paramecium2. Phylum – Ciliates• Cilia - hairlike structures - help

organisms move, get food and sense environment.

• Some unicellular, most are multicellular with 2 nuclei: one for everyday functions and one for reproduction

• http://www.youtube.com/watch?v=l9ymaSzcsdY&feature=fvw

Ciliates, cont.

• oral groove lined with cilia - moves H20 containing food into food vacuole at end of oral groove.

• food vacuole breaks down food and sends through cell.

• anal pore sends out waste.

Oral groove

Contractile

Vacuole

Food vacuole

food

vacuole anal pore

macronucleus

micronucleus

Paramecium

Protozoans with flagella3. Phylum zooflagelates• Use long whiplike part called

flagella to move. (one or two)• These usually live inside other

organisms

• Trichomonas vaginalis: an STI

Non Motile Protozoans4. Phylum Sporazoa - parasites

• Feed on cells & body fluids of host

Sporozoans like plasmodium (causes malaria) feeds off liver and blood cells

Plantlike Protists

• Better known as algae • Autotrophs (photosynthesis)• Size: unicellular to very large• Contain different pigments so

they come in different colors.• Algae perform 55-75% of all

photosynthesis on Earth so it provides most of the world’s oxygen!

• Ex: colonial volvox

White cliffs of Dover are white from plant-like protist shells

Kelp forests

Funguslike Protists

• Funguslike protists are heterotrophs that absorb nutrients from dead or decaying organic matter (decomposers/saprobes)

• Ex: slimemold, watermolds

Examples of slime molds

Funguslike Protists cont…

• Land-dwelling water molds cause a number of plant diseases, including mildews and blights.

• A water mold Phytophthora infestans was responsible for the Irish Potato Famine of the 1845-1848

Parasitic Protists

Biology 112

Parasitic ProtistsParasite: an organism that lives off of a HOST

organism (either on it or in it) and causes harm to the host.

Vector: an organism that carries parasite, and can transfer the parasite to another organism.

Parasite Vector Host

MALARIA

Protist – PlasmodiumVector – Female Anopheles Mosquito

• 4 species of protozoans that carry malaria but Plasmodium falciparum is especially deadly

• http://www.youtube.com/watch?v=JwsoK8O0lXE

Vector / Protist?

Liver

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Liver cell

Female Anopheles mosquito – site of sexual phase of plasmodium

Plasmodium sporozoites infect liver cells and reproduce asexually

Merozoites reproduce asexually in RBC’s

Red Blood CellsRed blood cell bursts and merozoites infect more RBC’s

Malaria

• WHO: 300-500 million cases/year• 1.5-2.7 million deaths/year (more than AIDS)

• Symptoms: fever, headache, vomiting and other flu-like symptoms

• The protist lives inside the bloodstream eventually clogging capillaries and destroying blood cells, leading to death if untreated.

• http://www.youtube.com/watch?v=JwsoK8O0lXE

Giardiasis• Protist - Giardia• Infects ~ 200 million people worldwide

• Transmission: contaminated water (outdoor streams, other untreated water sources); day-care environments (fecal-oral route)

• Takes up residence in the digestive tract.

• Symptoms: severe diarrhea and vomiting.

Giardia

African Sleeping Sickness

• Protist – Trypanosoma• Vector – Tse Tse Fly

African Sleeping Sickness• Occurs mostly in sub-saharan Africa

• Initial symptoms: fever, headaches, pain in joints

• Infects the CNS: causes confusion, lack of coordination and uncontrolled sleepiness.

• Leads to death if left untreated.• http://www.youtube.com/watch?v=4aVUrGO97Zg

http://upload.wikimedia.org/wikipedia/commons/c/c7/AfrTryp_LifeCycle.gif