Protists Flashcards
What are protists?
- A large and diverse group of unicellular eukaryotic microorganisms
Where can protists be found?
- Inhabitants of water, soil, and animal digestive tracts
- Different species have different habitats
Free living (don’t require anything to survive) and host associated
Describe absorptive nutrition?
Uptake of soluble nutrients across the plasma membrane
-Myxomycota, Dictyostelida, Acrasida
Describe ingestive nutrition?
Predation on bacteria or other protists
Pinocytosis (fluid uptake)
Amoeba, Actinopoda, Apicomplexa, Formanifera, Ciliophora, Flagellates
Particulate nutrients engulfed and contained within a membrane inside the cell
What are the two kinds of protist reproduction?
-Asexual
-Schizogony
Describe asexual reproduction in protists?
→ Most common system is binary fission one cell divides into two equal cells
→ plane of division varies with different organisms
Describe Schizogony reproduction in protists
→ nucleus and intracellular organelles divide repeatedly prior to cell division
→ large numbers of progeny released at once
→ dividing cell is a Schizont (meront)
→ daughter cells are Merozoites: identical copies to the mother cell
What are Sarcodina?
-Amoeboid organisms
-No fixed cell shape
-Diameter from 10-60 mm
-Cytoplasm subdivided:
ectoplasm and endoplasm
Asexual reproduction by mitotic cell division
Cells in constant motion along surfaces
Survives adverse conditions by forming cysts- harder to treat and kill
Move by pseudopods
Entamoeba histolytica: causes amoebic dysentery, destruction of intestinal lining with diarrhea
Acanthamoeba: grows in water, infects cornea and can cause blindness
What are Entamoeba histolytica?
-Entamoeba histolytica: amoebic dysentery
Cysts ingested with contaminated food or water
-Germination and growth in the intestine, attached to the epithelial cell layer
diarrhoea, bowel destruction
-Complications when trophozoites migrate:
Can infect liver and brain- can be fatal
What are cilophora?
*Ciliates have two kinds of nuclei
-Macronuclei: large polyploid nucleus that regulates daily metabolic activities
-Micronuclei: one or more small nucleus which are genetic reserve of the cell
*Ciliates can reproduce asexually by:
transverse binary fission and occasionally
budding
*Ciliates can reproduce sexually by conjugation
Move by cilia- a minute short hair like process
*Complex cells
*Balantidium coli is the only human parasite that is a ciliate
*Causes a rare, though severe type of dysentery-when an infection gives you diarrhoea with blood in it
what are mastigophora?
-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 disease can be caused by mastigophora?
Trypanosomiasis
What are the symptoms and effects of trypanosomiasis?
*Fevers, chills, headaches and loss of appetite
enlargement of the spleen, liver and lymph nodes
meningoencephalomyolytis and haemolysis (red blood cells lyse)
progressive symptoms culminating in coma and death as they are able to cross the blood brain barrier
What are apicomplexa?
-Obligate parasites
-Apical complex for penetrating host cells
-Many spread by biting insects
Multiple developmental stages:
-asexual in host
-Schizogony– asexual reproduction by multiple fission,
-found in some protozoa, especially parasitic sporozoans.
-sexual in insect
What is the difference between helminths and protists?
Helminths are parasitic worms and are multicellular unlike protists.
What is dracunculiasis?
-Formation of a blister which can burn or itch strongly
-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 can dracunculiasis be prevented?
-No reservoir outside of humans
-Prevent contact of infected people with water sources
-Filter water to remove intermediate host
