Chapter 26 Flashcards
Protists
An informal group of primarily aquatic eukaryotic organisms with diverse features
Protists are members of which domain?
Eukarya
Body plan of protists
Most are unicellular
some form colonies
some are coenocytic
some are multicellular
Most multicellular protists have relatively ___ body from w/out ___tissues
Most multicellular protists have relatively simple body forms without specialized tissues
Coenocytic
A multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis
Most protists are ___ at some point in their life cycle
Most protists are motile at some point in their life cycle
Protists can move by
pseudopodia, cilia or flagella
some protists have two or more means of locomotion
Most algae are ___ photosynthesizers
autotrophic photosynthesizers
Heterotrophs can obtain nutrients by
absorption or ingestion
Most protists reproduce ___ many also reproduce ___
Most protists reproduce asexually - many also reproduce sexually
Mitochondria and chloroplasts probably originated from
endosymbionts
Diversity in ultrastructure and molecular data suggests protists are ___
Paraphyletic
Five informal sub groups of protists
- Excavates
- Chromalveolates
- rhizarians
- archaeplastids
- unikonts
Excavates
Group of unicellular protists with flagella and a deep (excavated) oral groove
Many are endosymbionts and live in anoxic environments
Excavates include
- diplomonads
- parabasalids
- euglenoids
- trypanosomes
Diplomonads
One or two nuclei, no functional mitochondria, no golgi comples and up to eight flagella
Giardia
A parasitic diplomonad
Parabasilids
Anaerobic, flagellated excavates that live in animals
Trichonymphs and trichomonads
Exampls of parabasalids
Euglenoids
Most are unicellular flagellates
Some are photosynthetic
some heterotrophic species absorb organic compounds by phagocytosis and digest prey in food vacuoles
Trupanosomes
Excavate with a single mitochondrion that has an organized deposit of DNA (Kinetoplastid)
Many are parasitic and cause disease, often live in blood
Trpanosoma brucei
Trypanosomes parasite that causes African sleeping sicknedd
Chromalveolates
Most are photosynthetic
Probably originated by secondary endosymbiosis in which an ancestral cell engulfed a red alga
Tpes of chromalveolates
Alveolates and stramenopiles
types of Alveolates
Dinoflagellates, apicomplexans and ciliates
Alveolates
Have similare ribosomal DNA sequences and flattened vesicles inside plasma membrane
Stramenopiles
Water molds, diatoms, golden algae and brown algae
Have motile cells with two flagella, one hairlike
Dinoflagellates
Marine plankton that are generally unicellular; a few are colonial
Ciliates
Complex unicellular alveolates with a pellicle that gives them a definite but changeable shape
Two kinds of nuclei:
- Diploid micronuclei=reproduction
- Polyploid macronucleus=growth
Water molds
Stramenophiles once classified as fungi
Brown algae
Largest and most complex of all seaweeds; size range from a few centimeters to 75 meters
Rhizarians
A monophyletic but diverse group of amoeboid cells
Often have outer shells called tests
Types of rhicarians
Forams, actinopods, and certain shell-less amoebas
Foraminiferans
mostly marine rhizarians that produce chalky, many chanmbered tests
Actinopods
Mostly marine plankton rhizarians with axopods that protrude through pores in shells
Archaeplastids
Similar chloroplasts, suggesting that they developed directly from a cyanobacterial endosymbiont
Types of Archaeplastids
- Red algae
- Green algae
- Land plants
Red algae
Mostly tropical marine organisms, attaching to rocks or other substrates
Green algae
Mostly aquatic that share many same characteristics as land plants
Many are symbionts; endosymbionts, lichens
Unikonts
Single posterior flagellum in flagellate cells, such as sperm and motile spores
Separated from all other eukaryotes (bikonts) by evolution of triple-gene fusion
Amoebozoa
Unikonts that produce temporary, lobose cytoplasmic projections ar some point in their life cycle
Amoebas
unicellular, found in soil, water and other organisms
Asexually reproduce by splitting into two equal parts
Plasmodial slime molds
Feed as multinucleate plasmodia
plasmodium creep over damp, decaying debris, ingesting bacteria, yeasts, spores, and organic matter
Choanoflagellates
Single flagellum surrounded with a collar of microvilli that trap food
Closest living nonanimal relative of animals
