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1.3 Development in imaging technology and staining techniques

1.3 Development in imaging technology and staining techniques. Contrast. When light passes directly through cells in what is called brightfield microscopy, most cells are seen colourless

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1.3 Development in imaging technology and staining techniques

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  1. 1.3 Development in imaging technology and staining techniques

  2. Contrast • When light passes directly through cells in what is called brightfield microscopy, most cells are seen colourless • Staining or using colouring agents showed that particular stains attach to particular parts of the cell, improving contrast between internal structures and producing better images • Can be as simple as adding methylene blue or iodine • Chemical preservatives “fix” the cell and allow for more complex staining procedure • This kills the cell so it is not possible to view living tissue

  3. Staining Cells- Quick Lab • Page 254 • Do this in partners

  4. Resolution • Is the ability to distinguish between two structures that are very close together • An image should have high resolution if it is to show its detail • The clarity of images depends on the resolving power of the microscope • However light microscopes efficiency is limited because as light focusses onto smaller and smaller diameters, the image becomes blurry

  5. Fluorescence Microscopy • Read paragraph on page 256 • https://www.youtube.com/watch?v=sCYX_XQgnSA

  6. Confocal Technology • Read paragraphs on page 257-258

  7. Electron Microscope • Uses beams of electrons instead of a light wave and is able to produce images that provide fine detail • The image is formed by the absorption or scattering of electrons because electron-dense materials do not let the electrons pass through

  8. TEM • Transmission Electron Microscope depends on a beam of electrons passed through a very thin section of fixed (not alive) and stained tissue embedded in plastic • Can magnify up to 1 500 000x • A drawback is the difficulty in building up a three dimensional picture of a cell from a very thin section • There is great detail, but the area we are looking at is very small

  9. Light vs Electron Microscopes • Copy down Table C1.1 on page 259 • https://www.youtube.com/watch?v=WDkLxlQ3hBA

  10. Scanning Electron Microscope • This gives information about the surface features of a specimen. • Specimens are fixed and covered with an electron-dense material like gold which reflects electrons • 300 000x magnification • A form of the SEM has been developed to allow use to use live materials

  11. Electron Micrographs • Photographs taken by either the SEM of TEM • https://www.youtube.com/watch?v=SIOOLXbwWME

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