Microscopy and Magnification

• Electron microscopy uses a beam of electrons instead of light to magnify the specimen, allowing for higher resolution and greater detail.
• Transmission electron microscopy (TEM) uses a beam of electrons to pass through a thin specimen, producing a high-resolution image.
• Scanning electron microscopy (SEM) uses a beam of electrons to scan the surface of a specimen, creating a detailed 3D image.
• What's the calculation for magnification?

  Magnification = Image size / Object size
• Magnification triangle

  
• What is the function of a stage micrometer?

  To calibrate an eyepiece graticule so that it can be used to make measurements
• What is the function of a stage micrometer?

  To calibrate an eyepiece graticule so that it can be used to make measurements
• Outline the procedure to preparing a slide

  * Stain the sample with the appropriate dye

  * Mount the sample onto the slide

  * Place a cover slip carefully on top of the slide, avoiding air

  bubbles
• Define Magnification

  Magnification is how much an image has been enlarged by compared to the actual size of the object
• What unit are cells and organelles usually measured in?

  Micrometers (µm)
• What is resolution?

  The degree to which it is possible to distinguish between two close objects as being separate.
• Why do we need microscopes?

  The human eye can only see objects as small as around 50μm (0.05mm) so a microscope is required to see cells in any detail
• How does light travel?(EM)

  In waves
• How many objective lenses does a light microscope have?

  It has 3 objective lenses (X4, X10, X40) on the rotating mouthpiece
• Why can’t we see organelles like ribosomes using LM?

  Light ranges from 400-700nm, with mitochondria having a diameter of 1000nm, making them visible, while ribosomes, with a diameter of 22nm, are too small to be seen under visible light.
• The stage micrometer is a special microscope slide etched with a ruler exactly 1mm long, with 100 divisions
• The stage graticule is used to calibrate the eyepiece graticule
• Staining in microscopy is the process that helps to distinguish different cell features