Protists - Ch. 23 Flashcards
Excavata characteristics
Asymmetrical
single-celled
have a feeding groove
the group contains heterotrophs, autotrophs, and parasites
Three subgroups: diplomonads, parabasalids, and euglenozoans
Have two or more flagella
euglenazoans
subgroup to excavata
Can be heterotrophic, autotrophic, mixotrophic, or parasitic
Have long flagella that guide them towards light sources
Can be 10 to 500 μm in length
Unicellular
trypanosoams
excavata, eugleanzoans
Parasitic to humans, animals, insects and plants.
Causes sleeping sickness and Chaga’s disease
Has different forms depending on where it is in its life cycle.
Infects the tse tse fly, who then infects a human
The organism is known as the trypomastigote for most of the life cycle but is named epimastigote while in the tse tse fly’s midgut and before maturation.
euglena
Mixotrophic, but can only use photosynthesis when light is available.
When the Euglena is in dark areas, the chloroplasts shrink and stop functioning, so the Euglena has to find food in its environment.
Very fast swimmers.
Have a contractile vacuole, which helps with osmoregulation.
Does not have a cell wall.
Unicellular.
Has a photoreceptor to find light
Has an eye spot to filter light wavelengths.
chromalveolatas
Originated over a billion years ago
It is possible the Chromalveolata went through two endosymbiosis events. The first is that their common ancestor absorbed a red algae cell capable of photosynthesis. The second event was that algae cell had already been engulfed by a photosynthetic prokaryote before this. Although, some Chromalveolata don’t have red-algae organelles or have plastid genes.
Photosynthetic organisms.
There are two subgroups: alveolates and stramenopiles.
alveolata
subgroup to chromalveolata
Have alveoli, which are membrane bound sacks found under the plasma membrane.
The function of the alveoli is unknown but could be linked through osmoregulation.
Members of this group are: dinoflagellates, apicomplexans, and ciliates.
dinoflagelletes
chromalveolata, alveolata
Can be heterotrophs, photosynthetic, or both but most are photosynthetic.
Encased in a hard covering of silica.
Has two flagella.
One of the flagella helps the dinoflagellate guide through the water, and the second flagella moves it forwards and spins.
Live in both freshwater and marine habitats
Causes red tide, which is toxic and can kill fish, birds, and other sea life.
Can cause bioluminescence at night through ATP.
Unknown as to why they use it, but may be to scare off predetors
Dinoflagellates mitosis is closed, meaning that the spindle fibers separate without the nuclear envelope breaking down.
paramecium
chromalveolata, alveolata
Ciliates are covered in cilia, which helps the organism to move and ingest food.
Can be 10 to 30,000 micrometers in size
Have an oral groove, which is similar to a mouth, that catches and digests their food.
Have an anal pore that gets rid of waste.
Osmoregulation through contractile vacuoles.
Paramecia have a macronucleus, which is responsible for the function of a cell, and also a micronucleus, which is responsible for reproduction.
Live in freshwater habitats.
stamenopile
subgroup to the chromalveolates
Consists of algae and protist
Use either photosynthesis or are hetertrophs
Have two kinds of flagellum.
One is hairy and the other is smooth.
Some of the members of this group are unicellular, like diatoms, and other are multicellular, like brown algae.
Members of this group include: diatoms and brown algae
diatoms
chromalveolatas, stramenopile
There are over 100,000 species
unicellular
photsynthetic algae.
They are encased in a glass-like covering of silica.
Some have a raphe in their shell, which is a small slit that helps the diatom move by expelling mucopolysaccharides.
Mostly reproduce asexually, but occasionally can reproduce sexually.
Diatoms are important because they produce the diatomaceous earth, which is a key component in making detergent, insulation, and paint removers.
Also important to the carbon cycle because their carbon dioxide is not returned back into the atmosphere because saprobes are not able to reach them when they die.
brown algae
chromalveolates, stramenopiles
Brown algae is recognized by many as seaweed and is what makes up the giant seaweed, kelp.
They are multicellular and photosynthetic.
Live in marine habitats.
Do not have true roots or blades.
Instead, they have a stripe, the body of the algae that supports the blades.
The blades are similar to leaves, and they go to the surface for photosynthesis. To stay close the surface, the blades have air bladders to help them float up.
Brown algae have a holdfast to anchor the algae in place.
rhizaria
Many have an armor covering called tests.
Classified by DNA similarities.
Consists of: radiolarians, forams, and cercozoans.
Are very important for the carbon and nitrogen cycles because when they die and sink to the bottom, Rhizarias aren’t accessible by decomposers. This keeps the carbon away from the atmosphere because the carbon is too deep down to reach the atmosphere.
radiolara
subgroup to rhizaria
Have tests that are made of silica and make very intricate designs.
Has needle-like pseudopods from the central cell body and catches food.
Once radiolarians die, their shell sinks to the bottom and is usually preserved, which is why they are common in the fossil record.
forams
subgroup to rhizaria
Protists that are unicellular and heterotrophic.
Can range in size from 20 micrometers to a couple centimeters long.
Have a porous outer shell called a test.
Inside their shells, they keep and grow algae. They eventually harvest and eat these algae.
Have pseudopods that help them move, eat, and gather materials.
Live in freshwater and marine habitats.
cercozoa
subgroup to rhizaria
Can be with or without shells.
Consists of amoeba with needle-like pseudopods and protists with flagella.
Can live in freshwater, soil, and marine habitats.
