Protists Flashcards
What are protists
-Older text books use the term “Protozoa”, but newer name reflects changes in understanding of evolution of the organisms.
-A large and diverse group of
unicellular, eucaryotic microorganisms.
-Inhabitants of water, soil, and animal digestive tracts.
-Individual species have specific habitats.
Some Free-living
Some Host-associated
-Many exhibit complex life cycles and undergo differentiation during growth and reproduction
what are examples of protists
fungi, algae and slime moulds
what are some protist shapes
Euglena is spindle shaped, Amoeba has an irregular shape, and Paramecium is slipper shaped
how do protists move and what is their nutrtion
Protists commonly move with the help of pseudopodia, flagella, or cilia and Nutrition may be photosynthetic, or heterotrophic
what are the nutritional stratgies for protists
Absorptive nutrition. (osmotrophy)= Uptake of soluble nutrients= Myxomycota, Dictyostelida, Acrasida
Ingestive nutrition. (phagotrophy)= Predation on bacteria or other protists, Need to digest complex macromolecules= Amoeba, Actinopoda, Apicomplexa, Formanifera, Ciliophora, Flagellates
what is absorptive nutrtion
-Nutrient uptake across the plasma membrane
-Passive diffusion with soluble nutrients on one side
-Active transport between soluble nutrients on the other end
What is ingestive nutrition
-Particulate nutrients engulfed
e.g. bacteria
-Digestion within a membrane vesicle inside the cell
How is protist reproduction diverse
-Asexual= binary fission, multiple fission and budding
-Sexual= fusion of male and female gametes or Conjugation (unique to cilliates)
-All methods of reproduction are characteristic of individual species and help in their identification.
what happens in asexual reproduction
Binary fission is a commonly observed system= one cell divides into two equal cells, plane of division varies with different organisms and Paramecium
what is Schizogony
-is a common method of asexual reproduction
-nucleus and intracellular organelles divide repeatedly prior to cell division
-large numbers of progeny released at once
-Dividing cell is a Schizont
-Daughter cells are Merozoites
What is the protist diversity of organisms
->200,000 named species
~10,000 parasites
~human pathogens
what are 2 examples from the protist kingdom
- Euglenophyta- one-celled, make or take in food and most have one flagellum
- Ciliophora- one-celled, take in food and have cilia
Explain protist taxonomy
Classification based upon size, physiology and mechanism of motility:
-Sarcodina- amoeboid movement
-Ciliophora- cilia on outer surface
-Mastigophora- flagella (whiplash)
-Apicomplexa- no external organelles of motility
gliding
-Eugelenoids- phototrophic flagellates
what is Sarcodina: amoebas
-Amoeboid organisms= no fixed cell shape and Diameter from 10-60 mm
-Cytoplasm subdivided =ectoplasm and endoplasm
-Asexual reproduction by mitotic cell division.
-Cells in constant motion along surfaces= Move by generating pseudopods
-Survives adverse conditions by forming cysts.
look at differences between endo and ectoplasm
Echo= the more vicious clear outer of the cytoplasm in amoeboid cells
Endo= the more fluid, granular, inner layer of the cytoplasm in amoeboid cells
what is Acanthamoeba
grows in water, infects cornea and can cause blindness.
what does Entamoeba histolytica cause
causes amoebic dysentery, destruction of intestinal lining with diarrhea
what % of people have Sarcodina: amoeba in the population
1-40% of population in developing countries and Up to 10% of population in endemic areas of developed countries
what is Entamoeba histolytica
-amoebic dysentery
-Cysts ingested with contaminated food or water= 1-40% of diarrhoeal disease in developing countries and 1-10% of diarrhoeal disease in developed countries
-Germination and growth in the intestine, attached to the epithelial cell layer= diarrhoea and bowel destruction
Complications when trophzoites migrate:
Liver
Brain
-no accurate global prevalence data for E histolytica infection and amoebic dysentery
what does Acanthamoeba spp. act as reservoirs for
the bacterium
-Ingest the bacterium (phagocytosis)
-Unable to digest the bacterium
Trojan Horse!
what is Acanthamoeba spp.
-Legionella pneumophila is a BACTERIUM that causes a serious lung infection, High fever, Chest pain and breathing difficulties -15% fatality and Septic shock
-Organism contracted via contaminated water
what is Mastigophora
-Haemoflagellates- Leishmania and Trypanosoma
-human pathogens
-replicate within the blood stream of infected individuals.
-They are injected into the blood stream by biting insects.
-Single flagella.
-Multiple developmental stages.
what is sleeping sickness
- life threatening disease caused by reated parasite strains and transmitted by the tsetse fly
-people in early stages often arent diagnosed
what are the symptoms of sleeping sickness
-fever
-chills
-headaches
-loss of appetite
-enlargment of spleen, liver and lymph nodes
how do humans have an efficient response to the Trypanosoma species
Antibodies sproduced that result in killing of the parasite
what is Apicomplexa
-Obligate parasites
-Apical Complex for penetrating host cells
-Many spread by biting insects.
what are the developmental stages in Apicomplexa
asexual in host (Schizogony)
sexual in insect
what is a definitive host
host in which sexual stage resides
what are the 2 kinds of nuclei in ciliates
-Macronuclei: large polyploid nucleus that regulates daily metabolic activities
-Micronuclei: one or more small nucleus which are genetic reserve of the cell
how can ciliates reproduce asexually
transverse binary fission and occasionally budding
how can ciliates reproduce sexually
in conjugation
what are Ciliophora (ciliates)
-move by cilia
-Complex cells
-Balantidium coli is the only human parasite that is a ciliate
-Causes a rare, though severe type of dysentery
what is cilia
small hair-like protuberances on the outside of every eucaryotic cell
-responsible for locomotion and mechanoreception
what is dysentery
-a gastrointestinal disease
-caused by bacterial or parastitic infections
-causes diarrhea, fever, vomiting and nausea, weight loss, cramps
-Diagnosed with stool culture
-Treated with antibiotics
what is an example of a multicellular parasite
helminth- parastatic worms
are protists multicellular
no, unicellular
what is Dracunculiasis
-Guinea worm infection caused by Dracunculus mediensis
Nematode (round worm)
->3 million cases in 1992 prior to start of eradication program
-Now down to < 500
what happens in dracunculiasis
-Formation of a blister which can burn or itch strongly
-The blister bursts and gives rise to an ulcer with the female protruding (triggered by cooling through water contact)
-Embryos are squeezed out in response to cold water
how is dracunculiasis a preventable disease
-No reservoir outside of humans
-Prevent contact of infected people with water sources
-Filter water to remove intermediate host
-relavtively low cost educational campaigns have been made
