Magnification

• Magnification


  mm—> micrometres

  x1000

  micrometres—>nm

  x1000

  nm—> micrometers

  divided by 1000

  micrometers—>mm

  divided by 1000
• Magnification equation


  Magnification = image size/actual size
• Micrographs


  -an image from an electron microscope

  skill-identify cell types and structures
• Eukaryotic cells


  Look for membrane bound organelles

  >plant-cell wall, chloroplasts
• Prokaryotic cells


  -always smaller, flagella, can’t see any membrane bound organelles
• Magnification


  How much larger an object appears compared to its real size
• Field of view 


  The diameter of the area visible through the microscope
• Resolution


  The smallest interval distinguishable by the microscope, which then corresponds to the degree of detail visible in an image created by the instrument
• Light and electron microscopes


  The magnification is the same, but the resolution is better with the electron microscope image
• Light microscope benefits 


  -cheap

  -shows colour

  -easy to use

  -*can show dead or alive cells

  -cell movement can be studied

  -quick specimen preparation
• Light microscopes limitations 


  -Lower resolution (0.25 micrometers to 0.3 micrometers)

  -lower magnification (max is 1500x)
• Electron microscope benefits 


  -high resolution (0.001 micrometers)

  -higher magnification (100000x to 300000x)
• Electron microscope limitations


  -very expensive

  -requires cells to be killed

  -no movement can be seen

  -no colour

  -specimen preparation takes a few days
• TEM (transmission electron microscope)


  Goes through object/cross-section
• SEM(scanning electron microscope)


  Only surface of the object
• technology-fluorescent staining generates bring images. Immunofluorescence is a technique that uses flourescently stained antibodies to bind to specific targets proteins within a cell. Discovery-that protein in the cell membrane can move around and are not locked in place
• Technology-cryogenic electron microscopy is a transmission electron microscopy technique that is used to determine the structure of molecules at near atomic level resolution.

  e.g. Covid’s shape