28 Protists Flashcards
Are protists prokaryotes or eukaryotes?
Eukaryotes
In what organisms are contractile vacuoles found?
Protists
What are organisms that perform photosynthesis and autotrophic nutrition called?
Mixotrophs
What are ‘mixotrophs’?
Organisms that perform both photosynthesis and heterotrophic nutrition.
A venus fly trap performs photosynthesis but also digested flies as a form of heterotrophic nutrition.
Based on this how can venus fly traps be described?
As mixotrophs
How did plastids arise in algae?
Probably through the intake of cyanobacteria through endosymbiosis.
What theory explains the evolution of many protists?
‘Secondary endosymbiosis’
What is the ’secondary endosymbiosis’ hypothesis?
A hypothesis that describes the possible origin of plastids in protists.
It suggests that plastids evolved from a gram-negative cyanobacterium that was engulfed by an ancestral heterotrophic eukaryote (primary endosymbiosis)
What are amitochondriate protists?
Organisms without conventional mitochondria and with fewer membrane- bounded organelles than other protist groups.
(they are believed to be a basal group)
What are micorsporidians?
A group of species that were once classed as protists but are now regarded as fungi
What are protists divided into?
Excavata, Chromalveolata, Rhizaria, Archaeplastida and Unikonta
What protist group are land plants most closely related to?
Archarplastida
What protist group are animals most closely related to?
Unikonta
What protist group are fungi most closely related to?
Unikonta
Describe organisms of the excavata group of protists?
Some members of this supergroup have an “excavated” groove on one side of the cell body.
Two major clades (the parabasalids and diplomonads) have modified mitochondria; others (the euglenozoans) have flagella that differ in structure from those of other organisms
What are parabasalids?
A clade inside the excavata group of protists.
They have modified mitochondria.
What are diplomonads?
A clade inside the excavata group of protists.
They have modified mitochondria.
What are euglenozoans?
A clade inside the excavata group of protists.
They have a unique flagellum structure
What is giardia?
A parasite that can be found in polluted drinking water. If consumed it causes diarrhoea.
What is giardia classified under?
Protists:excavata
What is chromalveolata?
A protist group that includes many photosynthetic organisms such as diatoms. It also includes brown algae
What are brown algae classified under?
Protists, chromalveolata
What are diatoms classed under?
Protists, chromalveolata
What are diatoms?
Microscopic photosynthetic protists that are in the chromalveolata group.
True or False: Fungi can be carnivorous?
True: some use their hyphae to ensnare their prey
What is rhizaria?
A group of protists that contains many (but not all the) species of amoebas.
What are amoebas?
A group of microscopic protists that are found in both the Rhizaria and Unikonta groups.
They have pseudopodia for movement and capturing prey
How are amoebas in the Rhizaria group distinguished from Unikonta amoebas?
Those in the Rhizaria group have threadlike pseudopodia whereas those in the Unikonta group have lobe or tube shaped pseudopodia.
What are archaeplastida?
A group of eukaryotes that includes red algae and green algae along with the direct ancestors of land plants
What species are included in archaeplastida?
Red and green algae
How are red algae classified?
Protists, archaeplastids
How are green algae classified?
Protists, archaeoplastids
What are ‘colonial species’?
They are a cross between unicellular and multicellular species.
They form colonies that are a hollow
balls whose wall is composed of hundreds of biflagellated cells embedded in a gelatinous matrix. The cells are usually connected by cytoplasmic strands; if isolated, these cells cannot reproduce.
The large colonies will eventually release the small “daughter” colonies within them.
What are the subgroups of excavate?
Diplomonads, parabasalids and euglenozoans
Describe diplomonads?
A sub group of excavata protists.
They have modified mitochondria called ‘mitosomes’ that lack functional electron transport chains and hence cannot use oxygen in respiration. Therefore diplomonads get the energy they from anaerobic biochemical pathways.
Diplomonads have two equal-sized nuclei and multiple flagella.
What type of protists is giardia?
A diplomonad (sub-group of excavata)
What are the modified mitochondria of diplomonads called?
Mitosomes
What are mitosomes?
The modified mitochondria of diplomonads.
They lack electron transport chains and are thus anaerobic.
What are parabasalids?
A sub-group of the excavate group of protists,
They have modified mitochondria called hydrogenosomes that generate energy anaerobically, releasing hydrogen gas as a by-product.
What is T. vaginalis?
A protists in the parabasalid sub-group of excavate.
It is a STI that infects the mucus membrane of the vagina and outcompetes the natural bacteria
What is Trichomonas?
An infection of T. vaginalis protists in the parabasalid sub-group of excavate.
It is a STI that infects the mucus membrane of the vagina and outcompetes the natural bacteria
What protists have modified mitochondria?
Diplomonads and Parabasalids (both sub-groups of excavata)
What are the modified mitochondria of parabasalids called?
Hydrogenosomes
What are hydrogenosomes?
The modified mitochondria of parabasalids.
They generate some energy anaerobically, releasing hydrogen gas as a by-product.
What are euglenozoans?
A clade of protists in the excavate group.
The main unique feature is the presence of a rod with either a spiral or a crystalline structure inside each of their flagella
What are euglenozoans divided into?
Kinetoplastids and euglenids
What are kinetoplastids?
A group of protists in the Euglenozoan clade of Excavata that have a single mitochondrion that has a large organised mass of DNA called a kinetoplast.
What is a kinetoplast?
A large organised mass of DNA that is found in the sole mitochondrion of Euglenozoans in the Kinetoplasitds clade
What is an example of a kinetoplast?
Trypanosoma
What are Trypanosomas?
A species of protist in the Kinetoplastid clade of Euglenozoans.
They causes Trypanosomosis (sleeping sickness)
They also cause Chagas’ disease
What is trypanosomosis?
‘Sleeping sickness’ it is caused by Trypanosma protists in the kinetoplastid clade
What is Chagas’ disease?
A disease caused by Trypanosomas and carried by bloodsucking insects.
It leads to ‘congestive heart failure’
What is ‘congestive heart failure’?
It just means heart failure
What are Euglenids?
A clade of protists in the Eugelnozoans clade. They have a pocket at one end of the cell from which one or two flagella emerge.
Many are mixotrophs, others engulf prey by phagocytosis.
What is the structure of a typical euglenid?
They have an ‘eyespot’ which is an organelles that acts as a light shield so that only light form a certain direction can reach the ‘light detector’
They also have ‘pellicles’ which are protein bands underneath the plasma membrane that provide structural support.
Many are photosynthetic and thus have chloroplasts
Why are ‘light detectors’ important in euglenids?
It allows them to swim toward light. This maximises photosynthesis
Are protists prokaryotic or eukaryotic?
They are in the domain Eukarya and thus eukaryotic.
What is a pellicle?
A structure found in euglenids that consist of protein bands beneath the plasma membrane that provide strength and flexibility.
(Euglena lacks a cell wall.)
What is conjugation?
A method of increasing genetic variation found in some protists where two individuals exchange haploid micronuclei but do not reproduce
What is a thallus?
A algal body that is shaped like a plant i.e. a seaweed
What are algae that are shaped like plants called?
A thallus
What is the structure of a thallus (seaweed etc.)
A typical thallus consists of a rootlike holdfast, which anchors the alga, and a stemlike stipe, which supports leaflike blades . The blades provide most of the alga’s photosynthetic surface.
Do algae perform alternation of generations?
Yes
What does ’heteromorphic’ refer to?
A form of alternation of generations in which each generation (sporophyte and gametophyte) appear very differently.
Seen in many algae and all plants etc.
What does isomorphic refer to?
A form of alternation of generations in which each generation (sporophyte and gametophyte) appear very similar.
Found in some algae.
What are mycetozoans?
Slime molds
What are slime molds classed as?
Protists (Unikonta)
