A2.2

• What is the core content part of the cell theory?

  All living things are made up of one or more cells
• How did scientists conclude that all living things are made of cells?

  They observed various organisms under microscopes and found cells in all samples
• What is the maximum magnification achievable with a light microscope?

  Up to 1,000 times magnification
• What are the steps to calculate magnification using a scale bar?

  1. Measure the length of the scale bar in the image.
  2. Convert the measurement to the same units as the actual size.
  3. Divide the size of the image by the actual size.
• What is the size of the scale bar in the example given?

  15 mm
• How do you convert millimeters to micrometers?

  Multiply by 1,000
• If the actual size of an object is 5 micrometers, what is its size in millimeters?

  0.005 mm
• What is the magnification if the size of the image is 15 mm and the actual size is 5 micrometers?

  3,000 times
• What should your numerical answers for actual size be between?

  1 and 1,000
• What happens if your numerical answer is not between 1 and 1,000?

  You need to convert your units
• What is a limitation of light microscopes compared to modern microscopy techniques?

  They have relatively low magnification and resolution
• What is a drawback of using electron microscopes?

  They only produce black and white images and require killing the sample
• What is the purpose of fluorescent stains in microscopy?

  To absorb light and re-emit it at a different wavelength
• What is immunofluorescence used for?

  To bind antibodies to different structures for identification
• What is the process of freeze fracture electron microscopy?

  • Rapidly freeze a sample
  • Use a steel blade to fracture the sample
  • Remove some ice and attach vapor to create a surface replica
  • View the replica in an electron microscope
• What is cryogenic electron microscopy used for?

  To understand protein structure and observe proteins in different forms
• How does cryo-EM differ from other forms of electron microscopy?

  It allows viewing proteins in various forms, not just their stable state
• What advancements does cryo-EM provide in biology?

  It enables real-time observation of protein movement and interactions
• What are the key differences between light microscopes and electron microscopes?

  • Light microscopes can view living specimens; electron microscopes cannot.
  • Light microscopes produce color images; electron microscopes produce black and white images.
  • Electron microscopes have higher magnification and resolution than light microscopes.