Download 3-5 Protists

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Biology
Unit 3 – Infectious Disease, Background Paper 3-5
Protists
The kingdom Protista is composed of organisms that are single celled eukaryotes (having a cell nucleus). Most of the
members of this kingdom are not pathogenic (disease causing). The few that are pathogens are responsible for some of
the most wide spread diseases.
Malaria
The most common protist infection. Malaria is caused by the protist
Plasmodium1. Plasmodium is a member of the phylum Apicomplexa. Members of this
phylum are motile (move) primarily by wiggling and swimming. With over 300 million
people affected world wide with malaria and with more than 4000 deaths each day from
the disease it is one of the major causes of fatal infectious disease in the world.
Plasmodium attacking red blood cells
Caused by the protist Entamoeba2.
Belonging to the phylum Sarcodina these protists move about by extending portions of their bodies
into projections called pseudopods (false feet) and then flowing their entire body in the direction of
travel. They also use their pseudopods to capture food. Once captured the food particle is taken into
the body whole (phagocytosis). The main symptom of dysentery is severe diarrhea but these
symptoms may not show up for months or even years as the amoeba grow and multiply in the host’s
body. Complications occur when the amoeba eats through the intestinal lining and moves into the
main body cavity (coelom). Water supplies infected with the amoeba are the primary cause.
Amoebic dysentery
Amoeba
Giardia3 infection is caused by a protist belonging to the phylum
mastigophora. This phylum is motile using flagella. Flagella are long whip like
appendages that move the protist through the water. Giardia is the most common
water born infection in the United States. All regions of the United States have
reported water contaminated with this protist. Since the protist can easily live for
long periods of time outside a host’s body it is particularly difficult to control.
Primary symptoms are watery diarrhea and stomach cramps. Giardia is treatable
with a variety of drugs once it is diagnosed.
Giardiasis
Giardia
Sleeping Sickness
Sleeping sickness is a disease that is endemic (always present) in
many parts of tropical Africa. The incidence in some areas is as high as 20% of the entire
population. The protist Trypanosoma causes the disease and is transmitted by the tsetse
fly. The parasite replicates in the blood stream and crosses the blood – brain barrier
causing irrevocable nervous system damage even if the disease is treated. If left untreated
the infection is always fatal.
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Image public domain Center for Disease Control, USG
Image CC BY SA Pearson Scott Foresman
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Image public domain Cenetr for Disease Control
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Background 3-5,Protists2012
Text 2012
Greg Ballog
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Name ____________________________ Date ______________ Period ________
Title of Reading: 3-5 Protists
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Background 3-5,Protists2012
Text 2012
Greg Ballog
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