Topic 12 Flashcards
What are the four supergroups of protists?
i) Excavates
ii) SAR
iii) Archaeplastida
iv) Unikonts
What are the excavates?
This supergroup includes incellular protists with modified mitochondria and protists with unique flagella
What are the SAR protists?
Grouped by DNA similarities
May have originated by secondary endosymbiosis and dominate eukaryotic diversity in the oceans
What are the Archaeplastida?
Includes red algae and green algae and the closest relatives to land plants
What are Unikonts?
Include protists that are closely related to fungi and animals
What are the three clades in excavata?
i) Diplomonads
ii) Parabasalids
iii) Euglenozoans
What protists (2 clades) lack plastids, have modified mitochondria, live in anaerobic environments and are often parasites?
Diplomonads and Parabasalids
What characterizes euglenozoans?
A spiral or crystalline rod of unknown function inside flagella
What has one or two flagella that emerges from a pocket at one end of its cell?
Euglenids
What protist clade is a highly diverse monophyletic supergroup defined by DNA similarities?
SAR
What three major clades are in SAR?
Stramenophiles, Alveolates, and Rhizarians
How did SAR likely originate?
By secondary endosymbiosis of a photosynthetic red alga
What does the stramenophiles clade include?
Some photosynthetic organisms like diatoms, golden algae and brown algae
What are diatoms?
Unicellular algae with a unique two-part, glass-like wall of silicon dioxide
What are brown algae?
Largest and most complex algae that are multicellular and called “seaweeds”
What does the life-cycle of brown algae include?
The alteration of generations
What is alteration of generations?
Alternation of multicellular haploid and diploid forms
What happens in the alteration of generations in brown algae?
i) diploid sporophyte produces haploid flagellated spores called zoospores
ii) zoospores develop into haploid male and female gametophytes which produce gametes
iii) fertilization of gametes results in a diploid zygote which grows into a new sporophyte
What defines the clade of alveolata?
They have membrane-bound sacs (alveoli) under the plasma membrane
What clades are within Alveolates?
Dinoflagellates, Apicomplexans, and Ciliates
What are dinoflagellates?
Have two flagella and reinforced by cellulose plates that live in marine and fresh water
What are apicomplexans?
They are parasites of animals and spread infectious cells sporozoites
What are ciliates?
Heterotrophs that use cilia to move and feed and usually reproduce asexually
What are rhizarians?
Diverse group defined by DNA similarities and includes amoebas that move and feed by pseudopodia
