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Ch 4

Ch 4. Tour of the Cell. Cells. Smallest unit that shows properties of life Metabolizes Reproduces Cell Theory All organisms consist of one or more cells The cell is the smallest unit of life New cells arise from old cells Cells pass hereditary material to offspring. Microscopic Worlds.

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Ch 4

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  1. Ch 4 Tour of the Cell

  2. Cells • Smallest unit that shows properties of life • Metabolizes • Reproduces • Cell Theory • All organisms consist of one or more cells • The cell is the smallest unit of life • New cells arise from old cells • Cells pass hereditary material to offspring

  3. Microscopic Worlds • Microscopes led to the discovery of the cell • Discovered “animalcules” and wee “beasties” • Antoni van Leeuwenhoek • Robert Hooke

  4. Microscopic Worlds

  5. Cell Size • House DNA, protein molecules and internal structures • Obtain nutrients and diffuse nutrients and O2 • Smaller cells have a greater surface area to volume ratio than do larger cells • Surface area is significant for diffusion and osmosis

  6. 10 m 30 m 30 m 10 m Surface areaof one large cube 5,400m2 Total surface areaof 27 small cubes 16,200m2 Surface area : Volume • Volume= 30 um *30 um* 30 um=27000um • SA (large)= 6*(30um*30um)=5,400 um • SA (small)=(6*(10um*10um))*27=16,200 um

  7. Domains of Life • The 3 domains of life • Bacteria (prokaryotic cells) • Archaea (prokaryotic cells) • Eukarya (all other life forms)

  8. Prokaryotic cell Nucleoidregion Colorized TEM 15,000  Nucleus Eukaryotic cell Organelles Cells • Prokaryotic • Bacteria & Archaea • Eukaryotic • Protists, fungi, plants, animals Prokaryotic cells are simpler & usually smaller than Eukaryotic cells

  9. In Common • Bounded by plasma membrane • Ribosomes • Cytoplasm • DNA as genetic material

  10. Prokaryoticflagella Ribosomes Capsule Cell wall Plasmamembrane Nucleoid region (DNA) Pili Prokaryote • Do not have membrane bound nucleus • Have a cell wall outside their plasma membrane • Circular DNA strands • No membrane bound organelles

  11. Smooth endoplasmicreticulum Nucleus Roughendoplasmicreticulum Flagellum Not in mostplant cells Lysosome Ribosomes Centriole Golgiapparatus Peroxisome Microtubule Plasma membrane Intermediatefilament Cytoskeleton Mitochondrion Microfilament Eukaryote • Membrane bound nucleus • Linear DNA • Membrane bound organelles

  12. Eukaryotic Cells • A typical animal cell: • Contains a variety of membranous organelles (underlined) Smooth endoplasmicreticulum Nucleus Roughendoplasmicreticulum Flagellum Not in mostplant cells Lysosome Ribosomes Centriole Golgiapparatus Peroxisome Microtubule Plasma membrane Intermediatefilament Cytoskeleton Mitochondrion Microfilament Figure 4.4A

  13. Eukaryotic Cells Rough endoplasmic reticulum • A typical plant cell Smooth endoplasmic reticulum Ribosomes NUCLEUS Golgi apparatus CYTOSKELETON: Central vacuole Microtubule Chloroplast Intermediate filament Cell wall Plasmodesmata Microfilament Mitochondrion Peroxisome Cell wall of adjacent cell Plasma membrane

  14. Categories of Organelles • Structural support, movement, communication • Cytoskeleton, plasma membrane, cell wall (plants) • Manufacturing • Nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus • Energy processing • Mitochondria (animal), chloroplasts (plants) • Hydrolysis • Lysosomes (animals), vacuoles (plants), peroxisomes

  15. Plasma Membrane • Forms boundary around cell • Controls and regulates material transport -Semi permeable • Phospholipid bilayer

  16. Walls of two adjacent plant cells Vacuole Plasmodesmata Layers of one plant cell wall Cytoplasm Plasma membrane Plants and Cell Walls • Cell wall • Cellulose • Connect by plasmodesmata • Channels between adj. cells

  17. Tubulin subunit Actin subunit Fibrous subunits 25 nm 10 nm 7 nm Microfilament Intermediate filament Microtubule Cytoskeleton • Cell’s internal skeleton • Helps organize structure and activities • Consists of network of protein fibers

  18. Tubulin subunit Actin subunit Fibrous subunits 25 nm 10 nm 7 nm Microfilament Intermediate filament Microtubule Cytoskeleton • Microfilaments (actin filiments) • Enable cells to change shape and move • Intermediate filaments • Reinforce the cell and anchor certain organelles • Microtubules • give the cell rigidity, provide anchors for organelles, act as tracks for organelle movement

  19. Nucleus Chromatin Two membranesof nuclearenvelope Nucleolus Pore Roughendoplasmicreticulum Ribosomes Nucleus • Contains most of the cells DNA • Eukaryotic chromosomes made of chromatin • Enclosed by nuclear enveloper • Nucleolus • rRNA synthesized

  20. Ribosomes • Free and bound ribosomes • Composed of 2 subunits • Involved in protein synthesis

  21. Transport vesicle fromGolgi to plasma membrane Transport vesiclefrom ER to Golgi Rough ER Plasmamembrane Nucleus Vacuole Lysosome Nuclear envelope Smooth ER Golgi apparatus Endomembrane System • Interconnected structurally and functionally • Physically connected OR • Connected via vesicles

  22. Smooth ER Rough ER Nuclearenvelope Ribosomes Rough ER Smooth ER TEM 45,000 Figure 4.7 Rough Endoplasmic Reticulum • Membrane continuous with nuclear envelope • Makes more membrane • Transferred via vesicles • Bound ribosomes • Produces proteins • Transported or secreted

  23. Transport vesicle buds off 4 Fig. 4-9b Ribosome Secretory protein inside trans- port vesicle 3 Sugar chain 1 Glycoprotein 2 Polypeptide Rough ER

  24. Smooth ER • Lacks bound ribosomes • Involved in metabolic processes • Synthesis of lipids, hormones, enzymes • Stores calcium

  25. Golgi apparatus “Receiving” side ofGolgi apparatus Golgiapparatus Transportvesiclefrom ER TEM 130,000 New vesicleforming Transportvesicle fromthe Golgi “Shipping” sideof Golgi apparatus Golgi Apparatus • Vesicles from ER go to Golgi • Receives and modifies products

  26. Lysosomes • Digestive enzymes enclosed by membrane sac • Destroy ingested bacteria, recycle damaged organelles • Break down food Lysosome Digestion Vesicle containing damaged mitochondrion Digestive enzymes Lysosome Plasma membrane Digestion Food vacuole

  27. Transport vesicle(containing inactivehydrolytic enzymes) Rough ER Golgiapparatus Plasmamembrane Lysosomeengulfingdamagedorganelle “Food” Engulfmentof particle Lysosomes Digestion Foodvacuole Figure 4.10A Figure 4.10A Lysosomes

  28. Vacuoles Nucleus Chloroplast Centralvacuole Colorized TEM 8,700 • Membranous sac • Central Vacuole • hydrolytic function • Contractile • Food

  29. Peroxisomes • Metabolize fatty acids & inactivate toxins • Enzymes that digest peroxides • Come only from ER

  30. Mitochondrion Outermembrane Intermembranespace Innermembrane TEM 44,880 Cristae Matrix Mitochondria • Cellular respiration • Converts chemical energy to ATP • Phospholipid bilayer membrane • Has own DNA and ribosomes

  31. Chloroplasts • Convert solar energy to chemical energy (photosynthesis) • Stroma • Contains DNA, ribosomes and enzymes • Thylakoids • Interconnected sacs that form stacks called granum

  32. Endosymbosis • Hypothesis of endosymbosis • Mitochondria and chloroplasts were once small prokaryotes living independently • At some point, began living within larger cells

  33. Movement • Cilia • Short appendage, numerous • Move via coordinated beating • Stirs fluid around stationary cells • Flagella • Long appendage, whip-like • Move via bending • Pseudopods • Irregular long lobes • Bulge outward and drag cell

  34. Movement Cilia lining lungs

  35. Extracellular matrix • Holds cells to tissues • Protect and support PM • Integrins • Regulate behavior, transmit information, coordinate cells

  36. Cell Junctions Tight junctions Tight junctions can bind cells together into leakproof sheets Anchoring junctions link animal cells into strong tissues Gap junctions allow substances to flow from cell to cell Anchoring junction Gap junctions Extracellular matrix Space between cells Figure 4.18B Plasma membranes of adjacent cells

  37. Fig. 4-23

  38. Videos • Overview • http://www.youtube.com/watch?v=NiiLS_ovLwM&feature=related • http://www.youtube.com/user/greatpacificmedia#p/u/56/vCqQLoRaTNA • Basic cell structure http://www.youtube.com/watch?v=mphqugYoiQY&feature=related • Cytoskeleton • http://www.youtube.com/user/greatpacificmedia#p/u/55/5rqbmLiSkpk • Cell membrane and wall • http://www.youtube.com/user/greatpacificmedia#p/u/52/-aSfoB8Cmic

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