Concise Summary of Magnification and Microscopy Concepts

Magnification and Units of Measurement
  • Definition of Magnification (M): Ratio of image size (I) to actual size (A).
    Formula: M = I / A
  • Units: Magnification has no units.
  • Ensure image size and actual size are in the same units for calculation.
Common Units of Measurement
  • cm (centimetre) = 10^-2 m
  • mm (millimetre) = 10^-3 m
  • μm (micrometer) = 10^-6 m
  • nm (nanometer) = 10^-9 m
Calculating Magnification
  1. Example Calculation:
  • Given actual size = 25 µm, image size = 25 cm
  • Calculate: M = 25 cm / 25 µm = 10000
  1. Actual Size Calculation:
  • Given M = 10000, image size = 7 cm
  • Solve: 10000 = 7 cm / A, thus A = 0.0007 cm or 7 μm
Comparing Sizes of Cells
  • WBC vs RBC Size:
  • WBC: 35 µm
  • RBC: 7 µm
  • WBC is 5 times larger than RBC.
Types of Microscopes
  • Light Microscope:
  • Uses light, resolution ~200 nm, max mag. x1500.
  • Electron Microscope:
  • Uses electrons, resolution ~0.5 nm, max mag. x250,000.
  • Produces black and white images, requires dead specimens.
Important Concepts
  • Resolution: Ability to distinguish between two points. Depends on wavelength used:
  • Light microscope ~200 nm
  • Electron microscope ~0.5 nm.
Key Differences Between Light and Electron Microscopes
  • Light Microscope:
  • Color images, portable, live specimens possible, low res (200 nm).
  • Electron Microscope:
  • Black and white images, non-portable, only dead specimens, high res (0.5 nm).
Cell Structures
  1. Nucleus: Houses genetic information (DNA).
  2. Ribosomes: Sites of protein synthesis (70S in prokaryotes, 80S in eukaryotes).
  3. Mitochondrion & Chloroplast: Energy production via ATP synthesis. Mitochondria are involved in respiration, while chloroplasts are involved in photosynthesis.
  4. Cell Wall: Provides structure and protection in plant cells, made of cellulose.
  5. Vacuole: Stores cell sap, provides turgor pressure in plant cells.
Summary of Cellular Features
  • Prokaryotic Cells: Lacking true nuclei, smaller (0.5-5 µm).
  • Eukaryotic Cells: Larger (10-100 µm), contain membrane-bound organelles including a true nucleus.
  • Viruses: Non-cellular and parasitic, range from 20-300 nm, composed of nucleic acid and protein coat.