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Copyright Notice! This PowerPoint slide set is copyrighted by Ross Koning and is thereby preserved for all to use from plantphys.info for as long as that website is available. Images lacking photo credits are mine and, as long as you are engaged in non-profit educational missions, you have my permission to use my images and slides in your teaching. However, please notice that some of the images in these slides have an associated URL photo credit to provide you with the location of their original source within internet cyberspace. Those images may have separate copyright protection. If you are seeking permission for use of those images, you need to consult the original sources for such permission; they are NOT mine to give you permission.
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Cell Structure Prokaryotic before nucleus Eukaryotic true nucleus
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Comparing Cell Sizes Mycoplasma 0.3-0.8 µm E. coli 1x2 µm
Cyanobacteria 10 µm diam Plant Cell 30x75 µm Obviously eukaryotic Nucleus present Mitochondrion Bacterium Chloroplast Cyanobacterium Endosymbiosis: Eukaryotes are Chimeras!
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Cell Theory 1839 Theodor Schwann Prussian Zoologist 1810-1882
Theodor Schwann Prussian Zoologist Matthias Schleiden German Botanist 1. All living organisms consist of one or more cells. 2. Some organisms are unicellular, so cells are the fundamental unit of life. 3. New cells come from pre-existing cells by cell division. We can now add: 4. Cells must show all the properties of life. 5. All cells are basically similar in chemical and structural composition.
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Eukaryotic Cell Structure
Middle Lamella-pectin glue Cell Wall-cellulose+protein Cell Membrane-phospholipid -transport proteins Chloroplast -photosynthesis 70S ribosomes naked, circular DNA Cytosol-enzymes for -fermentation -glycolysis Mitochondria -respiration 70S ribosomes naked, circular DNA Nucleus-DNA linear histone bound -transcription -replication Vacuole toxic waste processing Endoplasmic Reticulum -internal transport 80S Ribosomes -protein synthesis -translation Vesicles -import/export package Golgi Apparatus -sorting -packaging Other eukaryotic organelles have been omitted here!
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TEM or SEM? of a Plant or Animal Cell?
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? ? ? Protist, Plant, Animal, Fungus? endoplasmic reticulum
endoplasmic reticulum internal transport ? 80S ribosome translation nucleus transcription, replication RNA ? ? DNA cytosol fermentation, glycolysis zymogen granule protein storage enzyme secretion mitochondrion respiration
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Origin of Eukaryotic Organelles
Extant Multicellular Animals Myxozoans Protozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes Euglenoids Archezoans Archaea Bacteria Kingdom Protista Eukaryotes ARE Chimeras! Cyanobacterium endosymbiosis Extinct Eubacterium endosymbiosis Though sketched here as single events, these endosymbioses were very likely multiple events! Original Cell
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Archezoans “Protozoan parasites without mitochondria or Golgi”
Oldest nucleated cells Diverged from other Eukaryotes 2bybp… prior to ER and Golgi evolution Lack peroxisomes Ribosomes are 70S but NOT 80S 400 species (many more likely unknown parasites!) Three phyla: Archaeamoebae/Pelobiontida (Pelomyxa) Metamonada (Giardia) Microsporidia
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Pelomyxa palustris Pseudopodia Endosymbiotic bacteria
Free-living in freshwater sediment (microaerophilic) Phagocytosis active Uroid Accumulate glycogen reserves At least 3 species of endosymbiont in each cell…two species are methanogenic archaeons! Glycogen body Anterior uroid (macropseudopodium) for amoeboid movement Vacuoles Smaller pseudopodia do not enlarge
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Reproduction: Mitosis of nucleus Cytokinesis by furrowing Nuclei
“Daughter” Amoeba What would you suggest has been a large component of this individual’s phagocytosis diet?
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wood particles and bacteria
Trichonympha Termite gut protist symbiont lacking mitochondria Protist has bacterial endosymbionts making cellulase for digesting wood particles taken in by phagocytosis And spirochete ectosymbionts for motility spirochetes nucleus wood particles and bacteria
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Figure 7-00 Page 119 microfilaments nucleus microtubules
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A TEM cross section of a cilium of a protist.
It shows the basic structure of all eukaryotic flagella… There are nine doublets of microtubules surrounding one pair. They are contained in cell membrane and surrounded by cytosol. The interaction of calcium, ATP and the proteins associated with the microtubules permit the microtubules to flexibly interact resulting in flagellar or ciliary motion. The flexible eukaryotic flagellum made of tubulin is sometimes called an undulipodium. Flagella are found in Protista Chromista and Animalia, but not in Rhodophyta, higher Plantae or Fungi.
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Euglenozoa Flagellated protists which can be photosynthetic
Odd features Protein pellicle instead of cell wall Odd mitochondria (discoid cristae) so unique endosymbiont Chromosomes remain condensed during interphase 400 species (many more likely unknown parasites!) Two sub-phyla: Kinetoplasta (Trypanosoma gambiense) sleeping sickness Euglenoida (Euglena) photosynthetic, chlorophyll a,b, paramylum (aka paramylon = ß-1,3-glycan)
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Euglena gracilis Posterior extension Mitochondrion Pyrenoid Nucleus
Chloroplasts Paramylon grain Protein pellicle (striations) Contractile vacuole Eyespot Anterior invagination With internal short flagellum Long flagellum rooted here also (not shown)
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Secondary Symbioses Extant Eukaryotes ARE Chimeras! Extinct
Multicellular Animals Myxozoans Protozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes Euglenoids Archezoans Archaea Bacteria Chlorophyte algal endosymbiosis Euglenoid mitochondria are unique! For euglenoids, the chloroplast is a secondary endosymbiosis. Eukaryotes ARE Chimeras! Cyanobacterium endosymbiosis Extinct Eubacterium endosymbiosis Though sketched here as single events, these endosymbioses were very likely multiple events! Original Cell
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Amoeba proteus A freshwater amoeboid protist
Engulfing a Staurastrum green alga Food vacuoles Contractile vacuole The pseudopodia assist in locomotion and phagocytosis, but they also secrete proteolytic enzymes to digest particles outside the cell. Nucleus Mitochondria Pseudopodia Marine relatives, the foraminifera, secrete calcareous shells, contributing to reefs and sands.
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Ciliophora Ciliated protists (9000 species!) Odd features
Cilia in various locations for locomotion and/or feeding Cells include membranous sacs (alveoli) for feeding/excretion Contractile fibers, some striated for shape change Stiffened plates just beneath the cell membrane Some discharge toxic extrusomes (trichocysts) for defense/hunting Polyploid macronucleus for normal cell functions (up to 860-ploid!) Diploid micronuclei for sexual reproduction and producing macronucleus Conjugation is one method of sexual reproduction
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Stentor polymorphus Funnel-shaped protist Cytostome rim is ciliated
Stentor polymorphus Funnel-shaped protist Cytostome rim is ciliated Food swept into alveolus Cilia Contractile vacuole Nucleus Holdfast Micronucleus Macronucleus
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Phaeophyta (Kingdom Stramenopila)
Photosynthetic, mostly marine brown algae Odd features Body multicellular, supported by water, so simple thallus Sometimes huge (45m!) thallus attached to substrate by holdfast Occasionally pelagic (floating) Sargassum in Sargasso sea Chloroplasts inside rough ER membrane Photosynthetic pigments: chlorophyll a, c, fucoxanthin Storage materials: laminarin polysaccharide Wall polysaccharides: cellulose and alginic acid Tinsel-type flagella on zoospores and gametes, so centriole present Gametangia: antheridia (male) and oogonia (female) Gametes: isogamous, anisogamous, oogamous 1500 species
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Sphacelaria (and diatom)
Here is a brown alga which I hope you have or will observe in laboratory… Sphacelaria (and diatom)
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More Secondary Symbioses
Extant Multicellular Animals Myxozoans Protozoans Tracheophytes Bryophytes True Fungi Slime Molds Red algae Brown Algae Green Algae Chrysophytes Euglenoids Archezoans Archaea Bacteria Chlorophyte algal endosymbiosis For brown algae, the chloroplast is also a secondary endosymbiosis. rer Eukaryotes ARE Chimeras! Cyanobacterium endosymbiosis Extinct Eubacterium endosymbiosis rough ER nucleomorph phaeoplast Original Cell
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Rhodophyta (A Separate Kingdom?)
Photosynthetic, mostly marine red algae Odd features Body multicellular, supported by water, so simple thallus Thallus attached to substrate by holdfast Rarely pelagic (floating) Unique chloroplasts indicate unique endosymbiosis Photosynthetic pigments: chlorophyll a, phycoerythrin, phycocyanin…colors can be red, brown, purple, blue, green, blackish! Storage materials: floridean starch in cytosol (-1,4-glycan) Wall polysaccharides: cellulose and agar or carrageenan No flagella, so centriole missing Gametangia: spermatangia (male) and carpogonium (female) Some species encrust with calcium carbonate…contribute to reefs 4000 species
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Compsopogon Here are some of the example red algae. Some of these you will or should have observed in laboratory. Caloglossa Porphyridium Callithamnion
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Porphyridium Cell Wall Cell Membrane Mitochondrion Nucleus
Stellate Chloroplast Floridean Starch Vacuole
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