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Chapter 4

Chapter 4. Cell Structure & Function. Pioneers. Robert Hooke, 1665 Viewed cork, noted “ cellulae ” (monk’s cells) Anton van Leeuwenhoek, 1676 First visualized “animalcules” Theodore Schwann, Matthias Schleiden , 1830s Described cell division, nuclei, all living things made of cells

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Chapter 4

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  1. Chapter 4 Cell Structure & Function

  2. Pioneers • Robert Hooke, 1665 • Viewed cork, noted “cellulae” (monk’s cells) • Anton van Leeuwenhoek, 1676 • First visualized “animalcules” • Theodore Schwann, Matthias Schleiden, 1830s • Described cell division, nuclei, all living things made of cells • Rudolf Virchow, 1858 & later • All cells arise from pre-existing cells

  3. Cell theory • Every living organism is composed of one or more cells • A cell is the smallest unit having the properties of life • The continuity of life directly arises from the growth and division of single cells

  4. Cell basics • Plasma membrane • Lipid bilayer • Regulates transport in/out of cell • Genetic material • Nucleus • Nucleoid • Cytoplasm

  5. Cell size • Metabolic activity related to cell volume and surface area • Volume increases faster than surface area • The speed and amount of “stuff” (waste & nutrients) across a cell membrane is determined by the surface area • Larger cell volume needs more nutrients and produces more waste • Eventually the cell becomes big enough that the membrane can’t transport “stuff” fast enough

  6. Cell types • Prokaryotes • Eukaryotes

  7. prokaryotes • “Before the nucleus”—no nucleus or membrane-covered structures (organelles) • True bacteria • Archaebacteria • Very small • Simplest cells

  8. prokaryotes • Nucleoid region • DNA (single loop) • Cell membrane • Cell wall (in some) • Capsule (in some) • Cytoplasm • Ribosomes • Pili • Flagellum

  9. eukaryotes • Nucleus and other complex organelles • Organelle—internal membrane-bound compartment that serves specialized functions. “Little organs” • Protozoans • Algae • Fungi • Plants • Animals

  10. eukaryotes • Complex systems

  11. eukaryotes • Nucleus • Control center • Houses DNA (6 feet!!!) • Nuclear envelope/membrane • Regulates transport of molecules • Receptors for signaling • Nucleolus • Constructs ribosomes

  12. eukaryotes • Endoplasmic Reticulum (ER) • Rough • Ribosomes attach • Protein synthesis • Smooth • No ribosomes • Lipid synthesis

  13. Eukaryotes • Ribosomes • Synthesize proteins

  14. eukaryotes • Golgi Bodies • Package and process proteins & lipids • Vesicles—sacs containing enzymes • Lysosomes—intracellular digestion • Peroxisomes—break down fatty acids & proteins • Vacuoles—large vesicles for storing food & water • Only some eukaryotes

  15. Eukaryotes

  16. eukaryotes • Mitochondria • Forms ATP (energy) • Requires oxygen • H+ stored in outer compartment, controlled flow into inner • Similar to bacteria: have their own DNA & ribosomes

  17. Eukaryotes (plants) • Plastids • Chlorloplasts—Photosynthesis (energy from light) • Chromoplasts—color • Amyloplasts—store starches • Central Vacuole • Storage (amino acids, sugars, ions, wastes)

  18. Eukaryotes (animals) • Centrioles—produce microfilaments during cell division.

  19. Eukaryote surface • Cell membrane—regulates movement of “stuff” in and out of cell • Cell wall—strong, gives permanent shape to cell

  20. cytoskeleton • Protein filaments between nucleus & plasma membrane • Microtubules—keep organelles & cell structures in place or move them • Can fall apart in controlled ways (amoebas) • Some poisons can affect

  21. cytoskeleton • Microfilaments • Thin filaments • Help in cell division (contracts midsection) • Anchor membrane proteins • Muscle contraction

  22. movement • Motor proteins move things within cells • Flagella—long outer structures for movement • Usually only a few • Cilia—short outer structures for movement • Usually many • Pseudopod • “False foot”

  23. Plant vs. animal • Plant cells • Have cell walls & cell membranes • Have plastids such as chloroplasts • Have a central vacuole • Do not have centrioles • Animal cells • Have cell membrane but no cell wall • Do not have plastids • Do not have a central vacuole • Have centrioles

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