Download Chapter 12 The Eukaryotic members of the microbial

Chapter 12
The Eukaryotic members of the
microbial world
Medgar Evers College, CUNY
Prof. Santos
• These organisms include Algae, fungi,
protozoa, and large multi-cellular animals
such as the arthropods and Helminths.
Algae
• The study of algae is known as phycology.
Properties
• Algae are photosynthetic, they contain
chlorophyll A, a light trapping pigment
needed for photosynthesis.
• Algae include both unicellular and multicellular members.
• Unlike plants, they lack a complex
vascular system and have relatively simple
reproductive structures.
• Are found in both fresh and salt water
• Make up a vast portion of the
phytoplankton found in Earth’s bodies of
water.
• Algae can be both microscopic and
macroscopic.
• Microscopic algae can be single cell organisms
or they can grow as long chains or filaments.
• They can live in groups called colonies such as
Volvox.
• Macroscopic algae are multicellular organisms
that consists of several parts such as holdfast,
stipe, blades, and some have a bladder
consisting of gas that allow them to float.
• *The algae cell wall is made up of
cellulose and pectin.
• *The red algae cell wall contains
carrageenan and agar which are used in
food products as stabilizers. Agar is also
used to make solid bacterial medium.
Diatoms
• unicellular algae that have silicon dioxide
in their cell wall. When these organisms
die, their shells sink to the bottom of ocean
and does not decompose. Deposits of
diatoms are mined for diatomaceous
earth. This substance is used for filter
systems, abrasives in polishes and
insulation.
Disease caused by algae
• Algae do not directly cause disease in
humans but can release toxins that when
taken in by humans can cause harm.
Examples!
1- Gymnodinium breve is a dinoflagellate that
causes red tide in warm waters of Florida and
Mexico. It produces a toxin called brevetoxin.
Fish ingest the G. breve and then humans eat
the fish. Symptoms include tingling sensation in
the mouth and fingers, reversal of hot and cold
perception, reduced pulse rate, and massive
diarrhea.
G. breve
2- Dinoflagellates of the Gonyaulax species
cause more serious problems. They
produce neurotoxins such as saxitoxin and
gonyautoxins.
Shellfish such as clams, mussels, scallops
and oysters ingest the dinoflagellates and
accumulate the toxins. People that eat the
shellfish experience shellfish poisoning.
G.verior
• Symptoms include general numbness,
dizziness, muscle weakness, and impaired
respiration that can lead to death.
3- Pfiesteria piscicida, this dinoflagellate
produces some of the most dangerous
toxins known that researchers working
with them must take extreme precaution.
Pfiesteria piscicida
4- some species of diatoms can secrete a
toxin known as domoic acid that when
ingested by humans can cause diarrhea,
memory loss, vomiting, nausea, and
abdominal cramps.
Diatoms
Protozoa
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Are eukaryotic in nature
Unicellular
Are not photosynthetic
Mostly asexual
• Are classified according to their mode of motility.
• three phyla you should know;
Sarcomastigophora, Ciliophora, Apicomplexa,
and Microspora.
1-Sarcomastigophora consists of 2 subphylum,
Sarcodina and Mastigophora.
A) Sarcodina move by means of pseudopods
includes the ameba.
B) Mastigophora move by means of a flagellum.
2-The phylum Ciliophora includes
microorganisms that move by means of
cilia, tiny hairlike projections.
3- The phylum Apicomplexa includes
Plasmodium, Toxoplasma, and
Cryptosporidium which cause serious
human diseases.
• Are aquatic and terrestrial in terms of
habitat
• Lack a cell wall
Diseases
• Please know table 12.2 where they list the
infections caused by the major protozoa
discussed in the book. Ex’s are
• Malaria caused by Plasmodium
• Amebiasis caused by Entamoeba
• Giardiasis caused by Gardia
• African sleeping sickness caused by
Trypanosoma
Fungi
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•
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Unicellular or multicellular
Eukaryotic in nature
Are non-photosynthetic
Cell wall is made up of chitin
Cells are not flagellated
Fungal groupings
1- yeast
• Unicellular
• 3 to 5 um in diameter
• Reproduce by binary fission or budding.
2- Molds
• Are filamentous
• One filament is called a hyphae.
Hyphae are divided into cells by
internal cross-walls called septa.
• A group of hypha is called a mycelium.
Septa
Other properties of fungi
• Are economically important for the food
industry such as beer, wine, and cheese
production.
• Antimicrobial agents are also produced by
fungi such as penicillin and griseofulvin.
Fungi cause human disease in
three ways
1-The fungi grows in or on the human body
2- A person might react to a fungal toxin
3- A person might develop an allergic
reaction to fungal spores or vegetative
cells.
Mycoses
• Fungal diseases
• The name of the individual disease often
begins with the name of the causative
agent of infection. Ex; histoplasmosis is
caused by Histoplasma capsulatum.
Fungal toxins
1- ergotamine, used to treat uterine bleeding
2- Aflatoxins, powerful carcinogen of the
liver.
Multicellular parasites
1- *Arthropods
2- Helminths
* Mainly biological vectors or mechanical
vectors.
Arthropods
• Include insects and arachnids
• Insects include mosquitoes, lice, and fleas.
• Arachnids include the ticks and mites
• Arthropods are mainly vectors that
carry agent of infection that causes
diseases such as malaria
(plasmodium), yellow fever (flavivirus),
plague (Yersinia pestis), typhus
(rickettsia), rocky mountain spotted
fever and lyme disease and equine
encephalitis.
• Mechanical vector- transfers agent from
one surface to another.
• Biological vector- are essential part of
the life cycle of the pathogen. Example
is the anopheles mosquito that
transmits plasmodium that causes
malaria.
Helminths
• Cause disease
• Three classes; nematodes, cestodes, and
trematodes.
Nematodes
• Round worms
• Cylindrical body with a digestive system
consisting of 2 openings, mouth and anus
• Free living in soil or water
roundworm
Cestodes
• Tapeworms
• Flat ribbon shaped bodies that are
segmented.
• The head or scolex has suckers for
attachment.
• No digestive system
• Tapeworms are associated with beef,
lamb, pork (Taenia solium) and fish.
Taenia solium
Diphyllobothrium latum
Trematodes or flukes
• Bilaterally symmetrical, flat and leafshaped.
• Most are hermaphrodites
• Have suckers for attachment and sucking
fluids from host.
Schistosoma mansoni
• Please know table 12. 5 and 12.6 for list of diseases
caused by these Helminths.
• Examples are
• Ascariasis caused by the roundworm Ascaria,
abdominal pain
• Trichinellosis caused by the roundworm Trichinella,
fever, swelling of eyelids, and muscle soreness
• Tapeworm disease caused by Diphyllobothrium
latum, a fish tapeworm, no symptoms maybe anemia
• Schistosomiasis caused by Schistosoma mansoni,
liver damage and malnutrition and weakness