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
Alveolata: List some characteristics of Dinoflagellates (zooxanthellae)
- large component of phytoplankton, foundation marine food chain, shape by internal plates of cellulose, spinning movement by two flagella in groove, red tide, toxin produce by filter feeder, deadly to humans who eat contaminated shellfish (Paralytic shellfish poisoning) - some form mutualistic symbiosis with corals and anemones - some bioluminescent
Alveolata: List some characteristics of Apicomplexans. Example?
- all are parasites of animals - intricate life cycles (often two different hosts) - Plasodium causes malaria (hides inside liver and blood)
Alveolata: List some characteristics of Ciliates. Example?
- diverse group - use cilia to move and feed (some completely covered, others have clustered rows or tufts) - Paramecium (cilia draw food which is engulfed by phagocytosis and expel accumulated water from contractile vacuole)
What are the characteristics of the Stramenopila Clade? Groups?
- Hairy flagellum paired with smooth flagellum (flagellated stage is often just reproductive cells) - Diatoms and brown algae
Stramenoila: List some characteristics of Diatoms.
- common type of phytoplankton (freshwater and marine) - two flagella - hairy and smooth - plastids have 3 membranes - secondary endosymbiosis - unique glasslike walls of hydrated silica - fossilized can form diatomaceous soil (natural abrasive and pesticide - by cutting insects exoskeletons)
Stramenopila: List some characteristics of Brown Algae.
- large, brown, commonly known as ‘seaweeds’ - inhabit intertidal and subtidal zones of coastal waters (temperate) - extreme physical conditions: wave forces and exposure at low tide - complex, multicellular resembling plants - holdfast (root-like), stipe (stem-like), and photosynthetic blades (leaf-like) - bladder floats near surface - no vascular tissue - brown colour due to accessory photosynthetic pigments - fucoxanthin - many have floats - giant ones known as kelp: important habitat for sea urchins and otters, fastest linear growth of any organism
What are the characteristics of the Amoebozoa clade? What groups are they divided into?
- lobe-shaped pseudopodia - unicellular heterotrophs: consume bacteria via phagocytosis - Amoeba and Slime Molds
Amoebozoa: List some characteristics of amoebas.
- 6 are parasites of human - Amoebic dysentry can be fatal, transmitted by contaminated water, “traveler’s diarrhea” or “montezuma’s revenge”
Amoebozoa: List some characteristics of slime molds.
- once thought to be fungi - fruiting bodies produce spores - convergent evolution - descended from unicellular amoebas - plasmodial and cellular
Amoebozoa: Slime Molds: Plasmodial Slime Molds. List some characteristics.
- brightly pigmented - form plasomdium - single mass of cytoplasm with multiple nuclei - feeding stage: extends pseudopodia through decomposing material, engulfing food via phagocytosis
Amoebozoa: Slime Molds: Cellular Slime Molds. List some characteristics.
- Good conditions, exist as one-celled individuals, like typical amoebas - Tough times, crawl to central location and become fuse into slug-like stage; travels to surface leaf litter; cells reconfigure to form fruiting body; millions of spores released to become single-celled organisms
What are the common characteristics of the Chlorophyta clade? Examples?
- evolved from common photoautotrophic ancestor - named for grass-green chloroplasts with chlorophyll a & b (similar to plants) - range in complexity: Unicellular (Chalmydomonas), Colonial (Volvox), Multicellular (Ulva, can qualify for seaweeds), symbiotically with fungi (lichen, a mutualistic collective)
What are some characteristics of the Rhodophyta clade?
- chlorophyll a - large enough t be ‘seaweeds’ - red coloration due to pigment phycoerythrin: absorbs wavelengths (blue and green that penetrate deep water) - found in depth of over 260m (deep for photosynthetic organism to survive)
