Analysis of Cell Components

• What is the difference between magnification and resolution?

  Magnification enlarges images; resolution details clarity
• What are the types of microscopes mentioned?

  Light microscopes and electron microscopes
• Why is it important to appreciate the time during which the community established between animals and cell types?

  It helps understand evolutionary relationships
• How are cell organization and cell fractionation used?

  To separate cell components for study
• What does magnification measure?

  How much bigger the image is than the specimen
• How is magnification calculated?

  $\text{magnification} =$$\frac{\text{size of image}}{\text{size of real object}}$
• If a magnified image is 5 mm wide and the specimen is 0.05 mm wide, what is the magnification?

  100
• If a specimen is 0.1 mm wide and the magnification is × 20, what is the size of the image?

  2 mm
• If a magnified image is 5 mm wide and the magnification is × 50, what is the size of the real object?

  0.1 mm
• Why must all lengths be in the same unit when calculating magnification?

  To ensure accurate calculations
• How many millimetres are in a micrometre?

  0.001 mm
• How many nanometres are in a millimetre?

  1,000,000 nm
• What is resolution in microscopy?

  How well a microscope distinguishes two close points
• What happens if a microscope lens can't separate two objects?

  Increasing magnification won't help
• What is the maximum resolution of optical microscopes?

  0.2 micrometers (µm)
• What is the maximum useful magnification of an optical microscope?

  About × 1500
• What is the maximum resolution of electron microscopes?

  0.0002 micrometers (µm)
• What is the maximum useful magnification of an electron microscope?

  About × 1,500,000
• What are the differences between optical and electron microscopes?

  • Optical:
  • Lower magnification (max × 1500)
  • Lower resolution (max 0.2 µm)
  • Electron:
  • Higher magnification (max × 1,500,000)
  • Higher resolution (max 0.0002 µm)
• What are the types of electron microscopes and their functions?

  • Transmission Electron Microscopes (TEMs):
  • Use electrons transmitted through specimens
  • High resolution images of internal structures
  • Scanning Electron Microscopes (SEMs):
  • Scan electrons across specimens
  • Produce 3D images of surfaces
• What are the advantages and disadvantages of TEMs and SEMs?

  • TEMs:
  • Advantages: High resolution images
  • Disadvantages: Only for thin, non-living specimens
  • SEMs:
  • Advantages: Can be used on thick specimens, 3D images
  • Disadvantages: Lower resolution than TEMs, non-living specimens only
• What is the first step in preparing a microscope slide?

  Pipetting a small drop of water
• Why are stains used in microscopy?

  To highlight objects in a cell
• What is an artefact in microscopy?

  Non-cellular objects seen under the microscope
• How can artefacts be distinguished from organelles?

  By preparing specimens in different ways
• What are the steps in cell fractionation?

  1. Homogenisation: Break cells to release organelles
  2. Filtration: Remove large debris from solution
  3. Ultracentrifugation: Separate organelles by mass
• What is the purpose of homogenisation in cell fractionation?

  To break up the cells and release organelles
• Why must the homogenised solution be kept ice-cold?

  To reduce enzyme activity that breaks down organelles
• What is the role of filtration in cell fractionation?

  To separate large debris from organelles
• How does ultracentrifugation work in separating organelles?

  By spinning cell fragments at increasing speeds
• What is the purpose of a buffer solution in homogenisation?

  To maintain the pH of the solution
• In what order do organelles separate during ultracentrifugation?

  Nuclei, mitochondria, lysosomes, ER, ribosomes
• What is the role of a cover slip in preparing a microscope slide?

  To protect the specimen
• Why is it important for the concentration of chemicals to match during homogenisation?

  To prevent damage to organelles through osmosis
• What should be avoided when placing a cover slip on a specimen?

  Getting air bubbles under the slip
• What is the significance of using a stain like eosin?

  It makes the cytoplasm visible
• What is the significance of using iodine in potassium iodide solution?

  It stains starch grains in plant cells
• What is the main limitation of optical microscopes?

  Cannot view organelles smaller than 0.2 µm
• What is the main advantage of electron microscopes over optical microscopes?

  Higher resolution and detail in images
• Why are artefacts more common in electron micrographs?

  Specimens require extensive preparation