(10) the cell theory 9 19


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(10) the cell theory 9 19

  1. 1. The Cell Theory – a timeline <ul><li>Late 1500’s: -first lenses used in Europe </li></ul><ul><li>-used to determine cloth quality (weave and precision) </li></ul><ul><li>-combos of lenses gave better view </li></ul><ul><li>Early 1600’s: Leeuwenhoek uses microscope to study nature </li></ul>
  2. 2. Early 1600’s Early 1600’s <ul><li>Leeuwenhoek </li></ul><ul><li>first to view pond water organisms </li></ul><ul><li>First to see living microscopic orgs </li></ul><ul><li>Made careful sketches </li></ul>
  3. 3. Robert Hooke ( 1665) <ul><li>Used light microscope to look at thin slices of plant tissues -- cork </li></ul><ul><li>Looked empty, like monk’s chamber </li></ul><ul><li>Called tiny chambers “cells” </li></ul>
  4. 4. Matthias Schleiden 1838 <ul><li>German Botanist (plants) </li></ul><ul><li>All plants looked at were made of cells, so concluded: </li></ul><ul><li>“ All plants are made of cells.” </li></ul>
  5. 5. Theodore Schwann -- 1839 <ul><li>German scientist who studied animals -- zoologist </li></ul><ul><li>Saw that all animals he studied were cellular so concluded: </li></ul><ul><li>“ All animals are made of cells.” </li></ul>
  6. 6. Rudolf Virchow -- 1855 <ul><li>German physician who studied cell reproduction </li></ul><ul><li>“ Where a cell exists, there must have been a preexisting cell…..” </li></ul>
  7. 7. The Cell Theory <ul><li>All living things are composed of cells </li></ul><ul><li>Cells are the basic units of structure and function in living things </li></ul><ul><li>New cells are produced from existing cells </li></ul>
  8. 8. Prokaryotes vs. Eukaryotes <ul><li>Prokaryotes: * NO NUCLEUS </li></ul><ul><li>*Small and Simple – few organelles </li></ul><ul><li>*Have cell membranes and cytoplasm </li></ul><ul><li>Ex. Bacteria </li></ul><ul><li>Eukaryotes: *Contain nuclei </li></ul><ul><li>*Contains organelles that perform specialized functions </li></ul><ul><li>*Uni-or multicellular </li></ul>
  9. 9. Figure 7.4 A prokaryotic cell
  10. 10. Basic Cell Structures <ul><li>Cell membrane – thin, flexible barrier around cell </li></ul><ul><li>Nucleus – large, centralized structure that contains genetic material and controls cellular activities </li></ul><ul><li>Cytoplasm – material inside membrane (but not inside the nucleus) that supports the internal cell shape and organelles </li></ul>
  11. 11. Basic cell parts: cell membrane and cytoplasm <ul><li>Cell membrane – </li></ul><ul><li>*provides barrier between internal and external environment of cell </li></ul><ul><li>*is semi-permeable (some things can go in, some cannot; some things can exit, some never can) </li></ul><ul><li>*made up of phospholipid bilayer with proteins embedded that allow for needed passage of large molecules </li></ul>
  12. 12. <ul><li>Major job of cell membrane is to maintain the cell’s environment – establish homeostasis </li></ul>
  13. 13. Fluid Mosaic Model <ul><li>Cell membrane and embedded proteins are not locked into position – they flow against one another as the cytoplasm and the external liquid environment dictate (so, is fluid) </li></ul><ul><li>There are MANY different components of the cell membrane – it is a mosaic of many parts </li></ul>
  14. 14. Figure 8.6 The detailed structure of an animal cell’s plasma membrane, in cross section
  15. 15. Nucleus <ul><li>Largest organelle </li></ul><ul><li>Enclosed by nuclear envelope or membrane, which is a double membrane – each of which is a lipid bilayer!!! </li></ul><ul><li>Nuclear membrane has pores in it </li></ul><ul><li>Contains inactive DNA – chromatin </li></ul><ul><li>When gets ready to divide, chromatin condenses into chromosomes </li></ul><ul><li>Directs protein synthesis by synthesizing mRNA and sending to ribosomes in the cytoplasm </li></ul>
  16. 16. Cytoplasm <ul><li>Entire region between the nucleus and the cell membrane </li></ul><ul><li>The semifluid substance that fills this area is called CYTOSOL , and this is what the organelles are suspended in </li></ul>
  17. 17. Cell Wall <ul><li>Found in plant cells (another barrier in ADDITION to the cell membrane) </li></ul><ul><li>Protects the cell </li></ul><ul><li>Gives support to cell </li></ul><ul><li>Made of polysaccharide called cellulose </li></ul><ul><li>Is very porous and allows molecules to pass through, but is NOT SELECTIVELY PERMEABLE </li></ul>
  18. 18. Organelles <ul><li>Control: </li></ul><ul><ul><li>*Nucleus (plant and animal) </li></ul></ul><ul><li>Assembly, Transport, and Storage: </li></ul><ul><ul><li>*Endoplasmic reticulum (plant and animal) </li></ul></ul><ul><ul><li>*Ribosomes (plant and animal) </li></ul></ul><ul><ul><li>*Golgi apparatus (plant and animal) </li></ul></ul><ul><ul><li>*Vacuoles (plant and animal) </li></ul></ul><ul><ul><li>*Lysosomes (plant and animal) </li></ul></ul><ul><li>Energy transformations: </li></ul><ul><li>*Chloroplasts (plant only) </li></ul><ul><li>*mitochondria (plant and animal) </li></ul>
  19. 19. Endoplasmic reticulum – “highway system” <ul><li>EXTENSIVE – accounts for more than half the total membrane system in eukaryotic cells </li></ul><ul><li>Name means “little net within the cytoplasm” </li></ul><ul><li>Smooth and rough e.r. are actually connected, not distinct, separate sections </li></ul><ul><li>Job is to transport materials quickly from one place to another in cell </li></ul>
  20. 20. Figure 7.11 Endoplasmic reticulum (ER)
  21. 21. Smooth e.r. <ul><li>Functions in synthesis of lipids, metabolism of carbs, detoxification of drugs and poisons </li></ul><ul><li>*Lipids – oils, phospholipids, steroids </li></ul><ul><li>(sex hormones and adrenal hormones) </li></ul><ul><li>*Liver cells – glycogen; gets converted to glucose phosphate which cannot leave cell, so e.r. makes enzyme that converts this to glucose </li></ul><ul><li>*Detox – liver; adds hydroxyl groups to drugs, makes them soluble and able to be flushed out of body </li></ul>
  22. 22. Rough e.r. <ul><li>Makes secretory proteins </li></ul><ul><li>(ex. Insulin made by pancreatic cells) </li></ul><ul><li>Most are glycoproteins (proteins covalently bound to carbs) </li></ul><ul><li>Rough e.r. is also a membrane factory – grows by adding proteins and phospholipids; parts can be taken from here and added to other membrane systems using the vesicles for transport </li></ul>
  23. 23. Ribosomes “protein factories” <ul><li>Sites of protein synthesis </li></ul><ul><li>Are made of rRNA and protein </li></ul><ul><li>Cells with high rates of protein synthesis have MANY ribosomes (human pancreas cell has MILLIONS of ribosomes) </li></ul><ul><li>Are “free” ribosomes in cytosol that make proteins for the cell that they are INSIDE of </li></ul><ul><li>Ribosomes that are attached to endoplasmic reticulum (bound) are making proteins for packaging and export OUTSIDE OF CELL </li></ul>
  24. 24. Figure 7.10 Ribosomes
  25. 25. Golgi apparatus “Gift wrapper/UPS system” <ul><li>Finishes, sorts, ships cell products </li></ul><ul><li>Golgi will modify products as needed – gives more variety by removing some monomers and substituting others </li></ul>
  26. 26. Figure 7.12 The Golgi apparatus
  27. 27. Vacuoles “Bank Vaults” or “trash cans” <ul><li>Sites of storage in cells </li></ul><ul><li>*good things stored – water, minerals, </li></ul><ul><li>food etc. </li></ul><ul><li>*bad things stored – broken down cell parts, waste </li></ul>
  28. 28. Lysosomes “suicide bags” <ul><li>Membrane-bounded sac of hydrolytic enzymes </li></ul><ul><li>Different lysosomes break down each of the major classes of macromolecules – proteins, polysaccharides, fats, nucleic acids </li></ul><ul><li>Work best at pH of 5 </li></ul><ul><li>Used in autophagy – recycle the cell’s own organic material for use </li></ul>
  29. 29. Mitochondria and Chloroplasts “powerhouses” <ul><li>Mitochondria – carry on cellular respiration – sites of energy production in cell (glucose broken down to produce ATP) </li></ul><ul><li>Chloroplasts – carry on photosynthesis </li></ul><ul><li>– sites where sunlight, CO2 and water are converted into glucose </li></ul>
  30. 30. Figure 7.17 The mitochondrion, site of cellular respiration
  31. 31. Figure 7.18 The chloroplast, site of photosynthesis
  32. 32. Cytoskeleton “hay in mud makes bricks” <ul><li>Network of fibers extending into cytoplasm of cell </li></ul><ul><li>Provides structural support, and aids in cell motility and cell regulation </li></ul><ul><li>Made up of microtubules (thickest), microtubules (thinnest), and intermediate filaments </li></ul>
  33. 33. Cilia and Flagella “hairs and tails” <ul><li>Cilia are short projections from cell body – hair-like </li></ul><ul><li>flagella are much longer – whip-like </li></ul><ul><li>Movement may not be for entire organism; may be part of a larger unit – ex. Cilia lining windpipe propel foreign substances out… </li></ul>
  34. 34. Organelles do not work alone… <ul><li>Cell is a dynamic interaction of ALL of its parts – literally, the basic unit of life…. </li></ul>