Cells and size

• Meter

  The base unit of measurement in science
• Sizes in biology

  • Often much smaller than a meter
• Centi

  One hundredth
• Centimeter (cm)

  One hundredth of a meter
• Size of objects

  • Width of little finger is around 1 cm
• Milli

  One thousandth
• Millimeter (mm)

  One thousandth of a meter
• Size of objects

  • Tip of a ballpoint pen is around 1 mm
• Micro

  One millionth
• Micrometer (μm)

  One millionth of a meter
• Size of objects

  • Typical human cell is around 10-20 μm in size
• Nano

  One billionth
• Nanometer (nm)

  One billionth of a meter
• Size of objects

  • Molecule of hemoglobin is around 5 nm in diameter
• Prefixes centi, milli, micro, and nano are used to describe sizes much smaller than a meter
• Smaller units like micrometers and nanometers are particularly useful when describing the size of cells and their components