Studying cells

• What methods helped scientists discover internal structures of cells?

  Microscopes and cell fractionation
• What are the three key types of microscopes mentioned?

  Optical, transmission, and scanning electron microscopes
• What is the definition of magnification?

  How many times larger the image is
• What does resolution or resolving power refer to?

  Minimum distance to view two separate objects
• What determines the resolution of an optical microscope?

  The wavelength of light used
• What determines the resolution of an electron microscope?

  The wavelength of the beam of electrons
• Why do optical microscopes have lower resolution than electron microscopes?

  Light has a longer wavelength than electrons
• What type of images can optical microscopes produce?

  Color images
• Why can't electron microscopes view living samples?

  Samples must be in a vacuum
• What type of image does a transmission electron microscope produce?

  2D black and white images
• How does a scanning electron microscope create images?

  By scattering electrons off the surface
• What is the formula for magnification in microscopy?

  Image size = actual size × magnification
• How do you convert millimeters to micrometers?

  Multiply by 1000
• If you measure 2 millimeters, how many micrometers is that?

  2000 micrometers
• If you have 2000 micrometers, how many millimeters is that?

  2 millimeters
• How do you calculate magnification using a scale bar?

  Image size divided by actual size
• Why must the eyepiece graticule be calibrated?

  Different magnifications change division values
• What is a stage micrometer?

  A glass slide with a scale on it
• How do you calibrate the eyepiece graticule?

  Use a stage micrometer to measure divisions
• If 20 divisions on the eyepiece graticule fit into 10 divisions on the stage micrometer, what is the ratio?

  2 divisions to 1 division
• If one division on the micrometer scale is worth 10 micrometers, what is one division on the eyepiece graticule worth if 2 fit into 1?

  5 micrometers
• How do you measure the size of a nucleus using the eyepiece graticule?

  Count divisions and multiply by division value
• If the nucleus covers 13 divisions and each division is worth 5 micrometers, what is the nucleus's actual size?

  65 micrometers
• What are the key differences between optical and electron microscopes?

  • Optical microscopes use light and can view living samples.
  • Electron microscopes use electrons and require a vacuum.
  • Electron microscopes have higher resolution and magnification.
  • Optical microscopes produce color images; electron microscopes produce black and white images.
• What are the steps to calibrate an eyepiece graticule?

  1. Place the stage micrometer on the stage.
  2. Align the eyepiece graticule with the stage micrometer.
  3. Count how many divisions fit into one division of the micrometer.
  4. Calculate the value of one division on the eyepiece graticule.
• What are the key points to remember about using microscopes?

  • Magnification formula: Image size = actual size × magnification.
  • Calibration of eyepiece graticule is necessary for accurate measurements.
  • Optical microscopes are limited in resolution compared to electron microscopes.
  • Electron microscopes can reveal internal structures of organelles.