A Tour of the Cell

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A Tour of the Cell

• Chapter 6
• Biology Campbell Reece

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How We Study Cells

• Microscopes
• Magnification
• Resolving Power or resolution
• 3 types of microscopes
• Light Microscopes a beam of light passes
  through the object, magnify up to 1000x,
  resolution of 0.2µm
• Transmission Electron Microscope (TEM) passes a
  beam of electrons through the object, greater
  magnification, resolution of 2nm
• Scanning Electron Microscope (SEM) passes a
  beam of electrons over the surface of the object,
  creates a 3-D image

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Compound Light Microscope
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Transmission Electron Microscope
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Scanning Electron Microscope
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Isolating Organelles

• Cell fractionation take cells apart and
  separate the major organelles
• Homogenization the disruption of cells
• Centrifuge at low speed separates the soup
  into a pellet and a supernatant
• The supernatant is then centrifuged at higher
  speed
• The process is repeated multiple times at higher
  speeds

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Cell Fractionation
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Prokaryotic vs. Eukaryotic

• All cells have plasma membrane, cytosol,
  chromosomes, and ribosomes
• Prokaryotic cells
• No membrane-bound nucleus
• Ex. bacteria
• Eukaryotic cells
• Have a membrane-bound nucleus
• Usually larger than prokaryotic cells
• Ex. Human skin cell

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Surface Area vs. Volume

• Larger organisms do not generally have larger
  cells, they have more cells

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REMINDER

• You are responsible for the information cell
  parts organelles (pages 100-119)
• Questions on the test may come from these pages!!!

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Extracellular Matrix

• Although they do not have a cell wall, animal
  cells do have an extracellular matrix made up of
  collagen, proteoglycans, fibronectins, and
  integrins

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Intercellular Junctions

• Plasmodesmata channels in cell walls (connects
  one plant cell to another)

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Intercellular Junctions

• 3 types in animal cells
• Tight junctions membranes of neighboring cells
  are fused
• Ex. between skin cells
• Desmosomes (anchoring junction) cells held
  together by filaments
• Ex. attach muscle cells to each other
• Gap junctions cytoplasmic channels between
  adjacent animal cells (similar to plasmodesmata)

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Intercellular Junctions (in animal cells)