Chapter 28 Flashcards
Eukaryotic cells initially evolved through
Horizontal gene transfer
Infoldings of membranes (Infoldings of plasma membrane to create membrane bound organelles (ER, nucleus)
Engulfing other cells (endosymbiotic theory)
Endosymbiosis origin
Mitochondria evolved from aerobic bacterium (rickettsia spp?) living within an archaeal host cell.
Chloroplasts of red, green algae, and plants evolved from an endosymbiotic cyanobacterium living within a mitochondria containing euk host cell. Red algae engulfed cyanobacteria, brown algae engulfed 1 or more red algae
(All euk have mitochondria, not all chlorplasts)
2 membranes, OG and engulfed, own ribosomes for proteins, own circular DNA, semi autonomous organelles, Gene transfer from organelles to host cell (mitochondria controlled by nucleus), replicate by binary fission
Eukaryote 6 supergroups
Chromalveolata
Rhizaria
Archaeplastida (plants)
Excavata
Amoebozoa
Opisthokonta (Animals, fungi)
Eukaryote difference from Prokaryotes
Not all protists have cell wall
Cell wall in eukaryotes
Diatoms, many cell walls from dead cells, glass, silica based.
Provide protection and support
Composed of polysaccharides and or glycoproteins (sugar proteins)
Euglena gracilis cell wall
Pellicle cell-interlocking protein strips to form a shell-like woven carbon fiber (wall like). More flexibility to move through environment (ones that move more need more flexibility)
Amoebas cell wall
Surrounded only by plasma membrane. Create extensions (Pseudopods) Moves towards or away from light, surround prey
Cysts
Resistant outer covering in which cell metabolism is almost completely shut down - suspended animation. Protect themselves from adverse conditions (similar to endospores)
Cilia
Small hairs, do a beating/flapping motion for movement. Not the same as pili - go in and out
Pseudopods
1 Type
False feet, engulf food & create food vacuoles (phagocytosis) movement. Could be big and broad or small.
Filopodia: Long tapered pseudopodium (Goes to a point)
Diatoms move
by currents, no flagella, bathed in nutrition
Autotrophs
Chemoautotrophs
Heterotrophs
Phagotrophs
Mixotroph
Autotrophs - chlorophyll if photosynthetic, make own sugars with light, CO2, Chem
Chemoautotrophs - Chemicals to create own sugars
Heterotrophs - Consume other organisms
Phagotrophs - Type of heterotroph that consume nutrition by phagocytosis
Mixotroph - ex. Dinobryon Do both photosynthesis and consume other organisms depending on environmental conditions
Asexual reproduction strategies
Sexual reproduction
Mitosis but differs from multi-celled organisms (Nuclear membrane stays intact and spindles form within nucleus)
Split into equal halves
Budding - one cell smaller than parent grows into adult size 0o to 0 0
Shizogony - cell division preceded by several nuclear divisions to produce several indviduals (1 to 8 or 6)
Meiosis production of haploid cells from diploid cells, process of producing offspring by fertilization and union of two cells
Zygospores
Thick wall resting cell protists and fungi. Arises from fusion of 2 gametes. Can remain dormant for a period of time. Once correct environment conditions it will create haploid/meiosis. Conjugation in Spirogyra. A filamentous green algae Helical chloroplast.
Excavata
Many lack typical/classical mitochondria, feeding groove looks like it was excavated (Channel)
Mitochondria double membrane bound organelle makes ATP
Other names - Hydrogenosome or mitosome (Greatly modified) or amitochondriate (lacking)
3 distinct groups: Diplomonads, Parabasalids, Euglenozoa
Diplomonads
SG Excavata
Two units (held together)
Characteristics - Absence of functional mitochondria (mitosome/non functional)
Live anaerobic environments - glycolysis to make energy (or fermentation)
Two cells, two haploid nuclei for each cell
Multiple flagella, generally 4 for each cell symmetrically arranged
Some free living but most are parasites
Giardia intestinalis - contaminated water, suck onto small intestines, trophozite, active form, cyst inactive, binary fission
Parabasalids
SG Excavata
Characteristics - Distinguishing feature - undulating membrane (wavy motion). Also have multiple flagella for locomotion. Lack mitochondria (modified anaerobic hydrogenosomes, produce hydrogen gas). Single nucleus. Symbiotic and parasitic.
Symbiosis between Pseudotrichonympha grassii and termites
Trichomonas vaginalis - STI itching, smell, discharge, bleeding, pain. Increased risk of HIV
Euglenozoans
Euglenids
Kinetoplastids
SG Excavata
Characteristics - Include free-living (Euglenoids) and parasitic groups (Kineotplastids). Change body shape-stretch or round. Most have 2 flagella. Autotroph, heterotroph, or mixotroph. Do have mitochondria but diverse in structure (ex chains)
Euglenids - 1/3 chloroplasts, fully autotrophic. Others lack chloroplast and move to find food. Some put in dark, chloroplasts become small/nonfunctional. Asexual. 2 flagella - 1 large flagellum, 1 within reservoir opening. Contractile vacuole. Stigma - eye spot (red)
Kinetoplastids - Single, unique mitochondria, unique DNA configuration. Unique processing of RNA during transcription (insert or delete Uridines to correct frameshift errors). Parasitism (separate group of parasite).
Leishmaniasis - S Amer, cutaneous -skin, visceral - internal organs, or mucosal.
Trypanosomes - Chagas disease (N & S Amer, kissing bug, cardiac, digestive issues), African Sleeping Disease (mosquito, nervous system)
Chromalveolata
2 Superphylums (SP)
These protists arise through secondary endosymbiotic events (eukaryote consuming another eukaryote).
The plastids in these organisms are those that contain chlorophyll c.
SP: alveolata and stramenopila
Alveolata - Defining characteristic - have flattened submembrane vesicles (alveoli - with cavities) stacked in layers, provides flexibility.
Dinoflagellates - characteristic
SG Chromalveolata, SP alveolata
Most photosynthetic, unicellular, two flagella, marine and freshwater, many have chloroplasts. Protective coat of two plates of cellulose, often encrusted with silica. Grooves at junction of plates, 2 flagella - one along the grooves spinning. Asexual with permanently condensed chromosomes inside nuclear envelope, no histone to wrap DNA
Bioilluminscence
Red tide
Apicomplexans characteristics
SG Chromalveolata, SP alveolata
Spore forming parasites of animals. Fibrils, vacuoles, cell organelles all at one end of the cell called apical complex (internals pushed to one end of cell). Plasmodium (malaria), Gregarines, Toxoplasma. Complex haploid and diploid life cycles
Plasmodium- spread by Anopheles mosquitoes, DDT, harsh drug vaccines, sickle cell allele more common in area of malaria. harder for protist to enter sickle cell.
Toxoplasma gondii - cat and rat feces, undercooked meat, usually no treatment, harmful to pregnancy and newborns.
Diatoms Characteristics
SG Chromalveolata, SP Stramenopile, Phylum Chrysophyta
Single celled, photosynthetic spp. with 2 part opaline silica shells. Chlorophyll A and C. Silica looks like glass, 2 parts fit together like petri dish. Insect control. Many different shapes. Some reproduce sexually when they get too small
Oomycetes characteristics
SG Chromalveolata, SP Stramenopile
Parasite or saprobes (Live off of dead organic matter). Spores (zoospores) have unequal flagella, 1 forward 1 backwards. Sexual reproduction with male and female organs. Most water, other plant pathogens. Potato blight (Phytophthora infestans). Saprolegnia- fish pathogen affects hatcheries
Rhizaria
Protists with slender pseudopods (Amoebozoans also have pseudopods). 3 groups: Radiolara, Foraminifera, Cercozoa
