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A Tour of the Cell

Delve into the fascinating world of cells, from humble beginnings with Leeuwenhoek's microscope to the modern understanding of organelles like the nucleus, ER, Golgi, and more. Explore the intricacies of cell structure, function, and relationships through the ages.

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A Tour of the Cell

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  1. A Tour of the Cell

  2. Anton Van Leeuwenhoek (1600’s) • Credit for the first microscope • Looked at pond water and saw “wee beasties”

  3. Robert Hooke • Observed plant stems, wood, and cork (1600’s) • Saw all the tiny chambers and called them CELLS • What cell part did Hooke observe? • Cell Wall

  4. Robert Brown (1833) • Observed that cells had a dark structure within plant cells • Brown observed the nucleus and stated that all cells have nuclei (at this time no one knew that the nucleus has DNA)

  5. Matthias Schleiden (1838) • Stated that all plants are made of Cells • Made many observations of plants around the area

  6. Theodor Schwann(1839) • Stated that all animals are made of Cells • Observed many animal tissues

  7. Rudolf Virchow(1855) • Stated that all cells come from pre-existing cells • Cells arise from the division of pre-existing cells

  8. The Cell Theory Microscopes Provide the Windows to the World of the Cell

  9. The Cell Theory • All living things are composed of cells • Cells are the basic unit of structure and function in living things • All cells come from pre-existing cells

  10. A Prokaryotic Cell

  11. The Size Range of Cells

  12. Cell Sizes Average Animal Cell – 15 microns Average Plant Cell – 40 microns Average Eukaryotic Cell :10-100 microns Average Prokaryotic Cell: 1-10 microns

  13. An Electron Microscope

  14. Geometric Relationships Explain Why Most Cells Are Microscopic

  15. Overview of an Animal Cell

  16. Human Cheek Cells

  17. Overview of a Plant Cell

  18. Onion Epithelial Cells

  19. Animal Cell’s Cell Membrane

  20. Cell or Plasma Membrane • “Fluid Mosaic” Model • Lipid Bilayer (made of phospholipids) • Proteins embedded throughout • Semi-permeable or Selectively Permeable

  21. Cell Wall • provides support to the • perimeter of plant cells, some • protists, and bacterial cells

  22. The Plasma Membrane

  23. The Nucleus and Its Envelope

  24. Nuclear Envelope/Membrane • Double Membrane that surrounds the nucleus • Lined with pores • Supported by nuclearlamina

  25. Nucleolus • Inside the nucleus • Site of ribosome and rRNA synthesis

  26. Ribosomes

  27. Endoplasmic Reticulum (ER)

  28. Endoplasmic Reticulum • (ER) • Rough ER • Intercellular transport of materials, particularly proteins; site where proteins leave ribosomes and are chemically modified

  29. Smooth ER • breaks down toxic • substances, • regulates Ca levels, • synthesizes steroids and • other lipids

  30. The Golgi Apparatus

  31. Golgi Apparatus • Modifies proteins and other substances from the ER for export from the cell

  32. Lysosomes

  33. Lysosomes • Digest cellular waste • and foreign substances • Breakdown of lipids, • carbohydrates, and • proteins

  34. The Formation and Functions of Lysosomes

  35. 1 Nuclear envelope is connected to rough ER, which is also continuous with smooth ER Nucleus Rough ER 2 Membranes and proteins produced by the ER flow in the form of transport vesicles to the Golgi Smooth ER cis Golgi Nuclear envelop 3 Golgi pinches off transport Vesicles and other vesicles that give rise to lysosomes and Vacuoles Plasma membrane trans Golgi 4 5 6 Lysosome available for fusion with another vesicle for digestion Transport vesicle carries proteins to plasma membrane for secretion Plasma membrane expands by fusion of vesicles; proteins are secreted from cell • Relationships among organelles of the endomembrane system Figure 6.16

  36. Peroxisomes • Contain an assortment of • enzymes that perform such • roles as detoxification of • alcohol, breaking down of • fatty acids • Produces H2O2 in theprocess

  37. Peroxisomes

  38. The Chloroplast, Site of Photosynthesis

  39. Plastids • May be called chromoplasts or leukoplasts • Store starch, fat or contain pigments such • as chlorophyll or carotenoids to capture energy from the sun

  40. The Mitochondrion

  41. Mitochondrion Site of cellular respiration and synthesis of ATP, a source of chemical energy for the cell

  42. The Plant Cell Vacuole

  43. Vacuoles • Store water, salts, • proteins, carbohydrates, • or enzymes

  44. The Cytoskeleton

  45. Cytoskeleton • Protein strands that give • the cell its shape and size • Helps organize the location • of organelles and their • activities

  46. There are three main types of fibers the make up the cytoskeleton: 1) Microtubules 2) Microfilaments 3) Intermediate Filaments

  47. Microtubules • Are made of the protein • tubulin • Shape and support the cell • Are responsible for the • separation of chromosomes • during cell division

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