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Chapter 7

Chapter 7. A Tour of the Cell. The Size Range of Cells. Prokaryote No membrane bound nucleus or organelles DNA is concentrated in a region called the nucleoid 1 – 10 μ m in diameter Include bacteria and archaea. Eukaryote Membrane-bound organelles

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Chapter 7

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  1. Chapter 7 A Tour of the Cell

  2. The Size Range of Cells

  3. Prokaryote No membrane bound nucleus or organelles DNA is concentrated in a region called the nucleoid 1 – 10 μm in diameter Include bacteria and archaea Eukaryote Membrane-bound organelles True nucleus (w/DNA) enclosed in a nuclear envelope 10 – 100 μm in diameter Include protists, plants, fungi and animal cells A Tour of the Cell

  4. A Tour of the Cell

  5. Animal Cell

  6. Plant Cell

  7. Animal Cell Have: Mitochondria Nucleus Cell Membrane Rough & Smooth ER Ribosomes Golgi Apparatus Cytoplasm Cytoskeleton Peroxisomes Also: Lysosomes Centrioles Flagella and Cilia Plant Cell Have: Mitochondria Nucleus Cell Membrane Rough & Smooth ER Ribosomes Golgi Apparatus Cytoplasm Cytoskeleton Peroxisomes Also: Chloroplasts Vacuoles Cell Wall Plasmodesmata

  8. Microscopes Transmission Electron Microscope (TEM) Scanning Electron Microscope (SEM)

  9. The Compound Light Microscope • Magnifies up to 1500x • Living and non-living specimens • 3-D image • Image produced using 2 lenses • Light must be able to pass through specimen

  10. Parts of the Microscope • Objectives • Left- Scanning- 4x • Middle-Low power-10x • Right-High power-40x

  11. Magnification - the ratio of an object’s image to its real size X Total magnification = eyepiece x objective

  12. Resolving Power The ability of a microscope to distinguish clearly between objects close together under a microscope Low resolution High resolution

  13. Field of Vision Amount of area visible under each objective

  14. Measuring the field of vision • How large is the field of vision pictured in mm? In μm? • Suppose you estimate 13 microorganisms could fit across this field of vision? How large is one microorganism in μm? 1 millimeter (mm) = 1000 micrometer (μm)

  15. Field of Vision Observe the next three slides. What is happening to the field of vision as the magnification increases?

  16. Field of Vision

  17. Field of Vision • What happened to the field of vision as you change from scanning to low to high power objective? • How would the object’s apparent size change?

  18. The Stereoscope • Also called dissecting microscope • Can view large opaque objects • Living and non-living specimens • Magnifies up to 100x • 3-D image

  19. Electron Microscopes Electron Microscopes – Electron beam focused through the specimen or onto its surface (electron beams have wavelengths much shorter than visible light) • Two types • Transmission Electron Microscope (TEM) – internal or ultrastructure • Scanning Electron Microscope (SEM) – surface of the specimen • Scanning Tunneling Microscope (STM) - views molecules at atom level

  20. TEM • Transmission Electron Microscope

  21. TEM • Beam of electrons pass through specimen • Magnifies up to 500,000x • 2-D image • Non-living specimens only

  22. TEM Collagen Fibrils in the cornea

  23. TEM • Plant Cell-22,500X • C = ChloroplastER = Endoplasmic ReticulumG = Granum M = Mitochondrion S = Starch GrainT = Thylakoids V = Vacuole W = Wall

  24. SEM • Scanning Electron Microscope • Electrons bounce off surface • Specimen placed in vacuum chamber

  25. SEM • Non-living specimens • 3-D image • Magnifies up to 60,000x

  26. SEM • Technician monitors image on screen

  27. SEM Pollen Grain

  28. Scanning Tunneling Microscope • Developed in 1980’s • Can view atoms on surface of objects • Non-living • 3-D image • Magnifies up to 100 million x

  29. STM • Barium, Copper, and Oxygen atoms

  30. STM • Silica atoms • A nanometer (nm) is one millionth of a millimeter

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