Sizes of Cells

• Metre

  The base unit of measurement in science
• Sizes in biology


  • Often much smaller than a meter
• Centi


  One hundredth of a meter
• 1 cm is 1 * 10^-2 m
• 1 mm is 1 * 10^-3 m
• Micrometer


  One millionth of a meter
• 1 micrometer is 1 * 10^-6 m
• Typical human cell size

  • 10-20 micrometers
• Nanometer


  One billionth of a meter
• 1 nanometer is 1 * 10^-9 m
• Hemoglobin molecule size


  • 5 nanometers in diameter
• Cells contain small parts like ribosomes that are measured in nanometers