Protists Flashcards
Protists
Protists are a diverse group of eukaryotic organisms, most of which are microscopic. Any organism not classified as a - plant, animal, fungus or bacteria - A kingdom of misfits
Describe common characteristics for protists.
- The majority are unicellular while some are multicellular
- Eukaryotic
- Mainly undergo asexual reproduction (spores) but some also reproduce sexually
- Like moist surroundings
What are the two life cycle patterns of protists.
Direct or monoxenous and Indirect or heteroxenous
Direct or monoxenous life cycle
There is only one host where the parasite spends most of its life as an adult and where it reproduces
Indirect or heteroxenous life cycle
There are two or more hosts that the parasite lives in during the life cycle.
Primary or definitive host
- Normally the larger of the hosts
- normally where the adult parasite lives
- where sexual reproduction takes place
Secondary or intermediate host
- the entering stages undergoes essential development before transmission
- frequently a number of developmental stages are involved
- development must occur to be considered an intermediate host
Transport Host
May involve predators. Often the parasite remains dormant until the transport host is eaten by the definitive host
The reservoir host
- Usually applies to a parasite which normally completes its life cycle in a wild animal host species
– Host/parasite association is usually well established
– Host is usually well adapted to the parasite and
tolerates the infection
Give an example of a reservoir host
Trypanosomes which infect domestic cattle in the African savannah. The wild animal population is infected with trypanosomes act as a reservoir hosts
and the parasite is transmitted to the cattle which contract the disease Trypanosomiasis.
What are the 3 groups of protists
Plantlike protists, fungi-like protists, animal like protists
Describe plantlike protists (algae)
- aquatic and contain chloroplasts
(carry out photosynthesis - autotrophs) - size range from a single cell (ex.
diatoms) to 60m in length (ex. green
algae) - some have flagella and able to swim
(ex. euglenoids) - some have cellulose cell walls
Describe fungi-like protists (slime moulds and water moulds)
Heterotrophs - some are parasites on fish, insects, and
plants (Harmful – ex. P. Infestans was a water mold which
caused the Great Potato famine in Ireland)
* Decomposers - some feed on dead matter (Beneficial –
recycles organic matter which results in providing nutrients
for plants)
* Like cool, shady moist places, leaves slimy trail as it moves
* Resemble protozoa and fungi
Describe animals-like protists : protozoa (“first animals”)
Heterotrophs - feed on other organisms or
dead matter (Example: amoeba and
paramecium)
* Lack cell walls
* Most are motile (some have flagella or cilia)
* Size range from 2 µm to 5 cm in diameter
* Many are parasitic
phagocytosis
the process in which amoeba surround and engulf their food
