2.2 Protists Flashcards
protists
-junk drawer of organisms
-includes all eukaryotes that do not fit “nicely” into the plant, animal or fungi kingdom
what are protists believed to have evolved from?
prokaryotic bacteria
give examples of the variety of niches and habitats protists can occupy
forest & ocean floors, sewage treatment plants, chlorinated swimming pools, and the atmosphere
what are the three types of protists?
animal-like, plant-like and fungus-like
example of an animal-like protist
amoeba and paramecium
example of a plant-like protist
euglena
example of a fungus-like protist
plasmodial slime mould
structure of protists
-mostly unicellular (some multi)
-some are colonial
-eukaryotic
-with membrane bound organelles
What are the 2 origin theories?
-could have been inward folding of membranes to create membrane bound organelles
-more likely Endosymbiosis of ancient unicellular prey by predator
what are the different methods of motility?
pseudopodia, cilia/flagella or none
describe how pseudopodia is a method of motility
amoeba creep by extending their cytoplasm to create ‘false feet’ (Pseudopodium, s.)
describe how cilia/flagella is a method of motility
-Others swim quickly using hairlike structures called flagella and cilia
-Flagella are long hairlike projections that extend out of the cell membrane
how do protists without a method of motility move?
some protists rely on water, wind currents and passing animals that they may hitch on to move them
Heterotrophic protists with flagella are called
_____________
Heterotrophic protists with flagella are called
zooflagellates
a group of protists that have an “apical complex” structure at the tip of the cell specialized for penetrating host cells are called ______________
apicomplexans
apicomplexans
These protists release reproductive cells called spores that can enter the bodies of other
organisms and live as parasites
what is the name of the apicomplexan that mosquitoes carry?
Mosquitoes carry the apicomplexan
Plasmodium, which causes malaria
Reproduction of protists
-Sexual
-conjugation
-Asexual
-Or Both
Animal-like protists
-heterotrophs
-endocytosis - engulfing food by extending membrane/cytoplasm
-e.g. amoeba
-ciliates sweep food into the oral groove
-e.g. paramecium
what is endocytosis?
engulfing food by extending membrane/cytoplasm
Plant-like protists
-autotrophs; have chloroplasts
-e.g. dinoflagellates, plankton, phytoplankton,
diatoms
true or false: green algae is a plant-like protist
false
-now considered a plant
What are dinoflagellates?
Unicellular protists with a cell wall made of
cellulose and two flagella are called dinoflagellates
What are red tides and how are they caused?
Red Tides – Harmful Algal Bloom
-kills fish, anything that eats shellfish
-worsening due to climate change
Fungus-like protists
-heterotrophs; saprophytes [feeds on dead material]
-e.g. plasmodial slime mould, cellular slime
mould, water mould
Importance of Protists
1) provide aquatic consumers with food and
oxygen
2) important symbiotic relationships with other
organisms
3) cause some of the world’s most serious diseases
give an example of a disease caused by a protist
E.g. Malaria
-Plasmodium, an animal–like protist needs two hosts: mosquitoes, humans
describe the cycle of plasmodium
-female mosquito infected by Plasmodium
-bites human
-Plasmodium enters circulatory system, liver…
-burst RBC, cause toxins to be released
-causes chills, fever
Explain why an amoeba and Paramecium are
considered “animal-like” protists
because they are heterotrophs that capture and ingest food
-amoebas use pseudopodia to capture their food
-paramecium use cilia to sweep food into their oral groove
Explain the role plankton play in most aquatic
habitats
The photosynthetic organisms in plankton are called phytoplankton, and they form the
base of food chains for most other aquatic organisms.
Identify the organism that causes malaria and
describe its life cycle
-plasmodium causes malaria
1) A mosquito infected with Plasmodium bites a human
2) Plasmodium infects human liver cells, which eventually burst, releasing a different form of the protist
3) Plasmodium infects red blood cells and
divides asexually. The red blood cells burst and release more Plasmodium cells
4) Another mosquito bites the infected person and
picks up Plasmodium cells.
5)Plasmodium reproduces sexually in the mosquito
What characteristic do all protists have in
common?
a nucleus and membrane bound organelles
What is HABs and how is it dangerous?
Harmful Algal Bloom
-HABs produce a toxin that can affect animals from fish to mammals, resulting in tissue damage and death.
-Although humans are usually alert enough to avoid the red water of HABs, we still face the
danger of eating contaminated animals, such as shellfish.
Summarize why protists have traditionally
been placed in their own taxonomic kingdom
in the six-kingdom system
Biologists have a sort of taxonomic
“stuff” drawer: the kingdom Protista. Protista is a very diverse kingdom of organisms that do not fit neatly into any of the other kingdoms
Describe three examples of structural diversity
found in protists
-Most protists are unicellular and free-living
(not parasitic).
-However, some protist species are colonial, organisms consisting of many similar or identical cells.
-There are even some protists, such as seaweeds like kelp, that are multicellular. These multicellular
protists have relatively complex bodies consisting of specialized cells.
What does the theory of serial endosymbiosis
propose about how eukaryotes may have
evolved from prokaryotes?
Scientists hypothesize that in this process, called serial endosymbiosis, chloroplasts and mitochondria evolved from small symbiotic prokaryotes that lived within other, larger host cells
What is the difference between the
plasmodium formed by a slime mould and
the Plasmodium that causes malaria?
plasmodium formed by a slime mould is a fungus-like protist
plasmodium that causes malaria is an apicomplexan
Even though euglena lacks a cell wall, why do biologists still classify it as a plant-like protist?
Even though Euglena lacks a cell wall, most biologists include it in this group, because it is mostly photosynthetic
