lect 4-&-5 cells-bsc-1010_f13_jc
TRANSCRIPT
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CellsLectures #4 & #5, Chapter 4
by John Cozza, Biology Dept.(some material modified from Raven, Biology 9th ed.)
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Cells outline
• What is a cell?• Types of cells• Cytoplasm
– Cytosol – Organelles– Cytoskeleton
• Cell wall and ECM– Cell junctions
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Cells outline
• What is a cell?• Types of cells• Cytoplasm
– Cytosol– Organelles– Cytoskeleton
• Cell wall and ECM– Cell junctions
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What is a cell?
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How did the first cell originate?
• Genetics first: RNA world
• Metabolism first• Proteins first• Membrane first• Hybrid world• Intelligent design?
http://pandasthumb.org/archives/2010/02/primordial-soup-1.html
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Interactive question #1
Intelligent design is not a scientific hypothesis because it is not
A.an educated guess
B.possible
C.controversial
D.testable
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One hypothesis of life’s origin…
• Micro-caves of undersea volcanic vents
• Metabolism first• Then RNA• Then proteins• Then DNA
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…and the first prokaryotic
cells (bacteria &
archaea)
• Then lipids & membranes
• Then cell walls
Martin, W. and M. Russell 2003. On the origins of cells: a hypothesis for the evolutionary transitions from abiotic geochemistry to chemoautotrophic prokaryotes, and from prokaryotes to nucleated cells. Phil. Trans. R. Soc. Lond. B 358: 59–85.
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Cell size
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Cells outline
• What is a cell?• Types of cells• Cytoplasm
– Cytosol – Organelles– Cytoskeleton
• Cell wall and ECM– Cell junctions
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Types of cells
Prokaryotic
Eukaryotic
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Prokaryotic cell
http://classes.midlandstech.com/carterp/Courses/bio225/chap04/sld003.htm
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Nitrosomonas sp. (Proteobacteria)Dirtland: http://commtechlab.msu.edu/sites/dlc-me/zoo/zdrs0232.html
Anabaena variabilis(Cyanobacteria)http://genome.jgi-psf.org/anava/anava.home.html
Some prokaryotes have internal membranes!
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Prokaryotic cell
E. coliBy David GoodsellScripps Institute
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Yellow = DNA, RNA, & proteinsBlue = Cytoplasmic proteinsPurple = ribosomesGreen = membranes + proteins
http://mgl.scripps.edu/people/goodsell/illustration/public
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TEM of eukaryotic cell
http://www2.estrellamountain.edu/faculty/farabee/BIOBK/biobookcell2.html
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Eukaryotic cell
Prokaryotic cell
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Interactive question #2The definitive difference between prokaryotic and eukaryotic cells is that prokaryotes
A.are smaller
B.are pathogens
C.do not have a nucleus
D.have a cell wall
E.lack internal membranes
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Eukaryotic cell sectionYellow & green = cell membrane and proteins
Blue = proteins
Blue filaments = cytoskeleton
Pink = ribosomes
Tan = mRNA, tRNA
From: Inside a Eukaryotic Cellby David GoodsellScripps Institutehttp://mgl.scripps.edu/people/goodsell/gallery/patterson.html
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Eukaryotic cell sectionYellow (L) = Golgi apparatus
Yellow (R) = mitochondrion
Blue = proteins
Green = glycosylation
Blue “Buckyball” = coated vesicle
Pink = ribosomes
Tan = mRNA, tRNA
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Eukaryotic cell section
Yellow = nuclear membrane
Blue = proteins
Orange “spaghetti” = mRNA being synthesized (R) and then spliced in nuclear pore (L)
Pink (R) = DNA
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Origin of eukaryotic cell: endosymbiosis
fermentation
photosynthesis
respiration
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Origin of the nucleus: alternative hypotheses
Martin, W. 2005. Archaebacteria (Archaea) and the origin of the eukaryotic nucleus. Current opinion in microbiology 8(6): 630-637.
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Origin of the nucleus: alternative hypothesis
Margulis, L. 2000. The chimeric eukaryote: Origin of the nucleus from the karyomastigont in amitochondriate protists. PNAS 97(13): 6954-6959
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According to the various hypotheses, the nucleus may have evolved from any of the following except:
A.A merger of a community of cells
B.A merger of a liposome and a chromosome
C.A spore
D.An engulfed cell
E.Infoldings of the cell membrane
Interactive question #3
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Cells outline
• What is a cell?• Types of cells• Cytoplasm– Cytosol – Organelles– Cytoskeleton
• Cell wall and ECM– Cell junctions
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Cytosol
• Water (~70%)• Ions• Building blocks ,
nutrients, etc.• Proteins (>20%)• Other
macromolecules• DNA (prokaryotes)
http://en.wikipedia.org/wiki/Cytosol
http://www.scripps.edu/news/scientificreports/sr2008/mb08olson.html
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Cytosol:E. coli
by David GoodsellThe Machinery of LIfeFig. 4.3
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Think—pair—share
What are the advantages to a eukaryotic cell of having organelles?
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Organelles (with membrane)Organelle Main features Function
Nucleus
Endoplasmic reticulum (ER)
Golgi apparatus
Mitochondrion
Chloroplast
Storage plastid
Vacuole
Lysosome
Microbody
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Nucleus and endomembrane system
Why are we considering them together?
White blood cellby David GoodsellThe Machinery of LIfeFig. 5.3
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Nuclear pore
by David GoodsellThe Machinery of Life, Fig. 5.3
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Endoplasmic reticulum (rough ER)
by David GoodsellThe Machinery of Life, Fig. 5.4
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Golgi apparatus
by David GoodsellThe Machinery of Life, Fig. 5.4
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Secretory vesicles leaving the cell
by David GoodsellThe Machinery of Life, Fig. 5.6
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Energy organelles
• Mitochondria (red)
• Chloroplast (deep green)
Euglena gracilis
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Mitochondrion
by David GoodsellThe Machinery of Life, Fig. 5.1
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Artemesia chloroplast
TEM by George Chapman
Chloroplast
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Artemesia chloroplast
TEM by George Chapman
Chloroplast internal membranesby David Goodsellhttp://cbm.msoe.edu/markMyweb/SUN-chlorophyllEbookWorking/chloroplast.html
Chloroplast
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Storage plastids
Cazzonelli, C. & Pogson, B. 2010. Source to sink: regulation of carotenoid biosynthesis in plants. Trends in plant science 15(5): 266-274.
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Plastids may function in all of the following except
A.photosynthesis
B.fruit ripening
C.food storage
D.cell respiration
Interactive question #4
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Vacuole
http://amit1b.wordpress.com/the-molecules-of-life/10-the-living-cell-gallery/
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“Organelles” with no membraneaka macromolecular assemblies
“Organelle” Location Main features
Function
Pyruvate dehydrogenase complex Replisome (DNA polymerase)
RNA polymerase
Spliceosome
Ribosome
Fill this table out as we go along…
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Ribosome
• rRNAs• Proteins
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Prokaryotic vs. eukaryotic ribosomes
Melnikov, S. et al. 2012. One core, two shells: bacterial and eukaryotic ribosomes. Nature Structural & Molecular Biology, 19(6), 560-567.
Blue = rRNARed = proteinLight = conservedDark = unique
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Eukaryote cytoskeleton
• Microtubules• Intermediate
filaments• Actin filaments
(microfilaments)• Motor proteins
Modified from David GoodsellThe Machinery of Life, Fig. 5.6
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Bacterial cytoskeleton!
The bacterial cytoskeleton. The only cytoskeletal element present in spherical bacteria such as S. aureus (top left) is the tubulin-like cell division protein FtsZ (green), which localizes in a ring at the onset of cell division, recruits other cell division proteins, and defines the division plane. Most rod-shaped bacteria (top right) also contain one or more actin-like MreB homologues (red), which exhibit helix-like localization patterns and are essential for cell width control. At the onset of cell division, the FtsZ ring forms and defines the division plane. C. crescentus, a vibrioid bacterium (bottom), contains a third cytoskeletal element, the intermediate filament-like crescentin (blue), which is required for cell curvature and localizes at the inner curvature of cells.
Cabeen, M. & Jacobs-Wagner, C. 2007. Skin and bones: the bacterial cytoskeleton, cell wall, and cell morphogenesis. The Journal of cell biology, 179(3): 381-387.
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Flagella
Bacteria
Eukaryotes
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Cells outline
• What is a cell?• Types of cells• Cytoplasm– Cytosol – Organelles– Cytoskeleton
• Cell wall and ECM– Cell junctions
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Bacterial ↑
Plant →
Fungal Cell walls:not a wall—a mesh
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Extracellular matrix: animals
↑ Human connective tissue with fibroblasts (darker)
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Cell junctions: animals
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Plasmodesmata: plants
http://www.mhhe.com/biosci/pae/botany/crang/vtphloem/sieve1/mg0700.html
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Interactive question #5Plasmodesmata are most like which cell junction in animals?
A.Tight junction
B.Desmosome
C.Gap junction
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Cells outline
• What is a cell?• Types of cells• Cytoplasm• Cell wall and ECM
Next:• Membranes