3. Chapter 28: Eukaryotes Flashcards
What are “protists”?
- so diverse, few general characteristics - mostly unicellular (colonial or multicellular) - most elaborate of all cells (single cell performs all basic function)
What are the nutritional diversity of protists?
- photoautotrophs 2. chemoheterotrophs 3. mixotrophs: combine photosynthesis and heterotrophic nutrition (i.e. euglena)
How do most protists move?
flagella or cilia - eukaryotic flagella not homologous to those of prokaryotes - 9 +2 microtubule sustem - cilia are shorter and more numerous
Where are protists found?
- almost anywhere there is water - damp soul and leaf litter
What are the protists an important part of?
of plankton: aquatic communities that drift passively or swim weakly
What is phytoplankton?
forms the base of most marine and fresh water food chains (cyanobacteria important member)
What are zooplankton?
primary consumers that feed on phytoplankton (many are not ‘protists’ but rather animals in adult or larval stage)
Many protists are symbionts. Where do that inhabit?
a host - mutualism to parasitism - some parasitic protist are important pathogens of animals
What are some examples of human diseases caused by protists?
- Malaria (Plasmodium) 2. African Sleeping Sickness (Trypanasoma) 3. Amoebic Dysentery (Traveler’s Diarrhea) 4. Giardia (Local Diarrhea drinking H2O)
What was an evolutionary trend of larger, more complex cells?
compartmentalization of cellular functions into organelles - endomembrane system (ER, Golgi) from infolding of plasma membrane - endosymbiosis (mitochondria and chloroplasts; were independent prokaryotes that entered host cells as undigested prey or internal parasites evolved to beneficial symbiosis)
What are the evidence that the mitochondria may have been independent prokaryotes at one point?
- Appearance 2. Genomes 3. Enzymes 4. Ribsome 5. Binary fission
Explain secondary endosymbiosis.
A protist engulfs an organism and retain its chloroplasts (ea. event adds a membrane)
Why are taxonomic groups with chloroplasts scattered through the phylogenetic tree?
those of plants and green algae have two membranes, other groups have three or four
The classic Darwinian view is that of linear descent through a series of ancestor but what does endosymbiosis imply?
- “horizontal” fusions (across the tree of life) - all three domains have DNA that has been transferred between domains - Replaces the classical ‘tree of life’ with a web-like phylogeny.
What characteristics do all three domains share?
- Plasma Membrane - DNA - Ribosome - Electric Transfer Chains
What do all bacteria share?
Peptidoglycan
What do Archaea and Eukaryotes have in common?
Histones and Introns
What characteristics does archaea have?
can live in temperatures of 100+ degrees celsius
What characteristics do Euglenozoa clade share?
- crystalline rod in their flagella - function unknown
What characteristic do Kinetoplastids share? (branch of Euglenozoa) What are the best known genus?
- single, large mitochondrion - kinetoplast: a DNA containing granules located within single mitochondrion - Trypanosoma (cause African sleeping sickness vectored by Tsetse Fly, changes surface proteins prevent host immunity development)
What is another branch of Euglenozoa? What characteristics? Example?
Euglenids; one/two flagella from anterior pocket, often mixotrophic; Euglena
What are characteristics of clade Diplomonadida? Genus?
- lacking mitochondria - two nuclei - thought to be primitive before mitochondria appeared, now known to have lost it secondarily - Giardia; causes giardiasis “beaver fever”, flagellated parasite of mammals, colonizes small intestine of human via feces contaminated water, severe diarrhea
What are the characteristics of the Alveolata clade?
- united by molecular systematics, few morphological connections except alveoli under plasmid membrane.
What are the three groups of Alveolata?
- Dinoflagellates 2. Apicomplexans 3. Ciliates
