cell biology

• Orders of magnitude

  A way to understand how much bigger or smaller one object is compared to another
• Prefixes to show multiples of units

  • Centi (0.01)
  • Milli (0.001)
  • Micro (0.000,001)
  • Nano (0.000,000,001)
• Light microscope

  Has two lenses (objective and eyepiece), magnifies up to x2000, resolving power of 200nm
• Electron microscope

  Uses electrons instead of light, magnifies up to x2,000,000, resolving power of 10nm (SEM) and 0.2nm (TEM)
• Calculations in microscopy: Magnification = magnification of eyepiece x magnification of objective, Size of object = size of image / magnification
• Standard form

  A way to represent very large or small numbers by multiplying a number between 1 and 10 by a power of 10
• Standard form

  Multiplying a certain number by a power of 10 to make it bigger or smaller, with the 'number' being between 1 and 10
• Standard form

  • 1.5 x 10^-5 = 0.000015
  • 3.4 x 10^3 = 3400
• Stem cell

  Undifferentiated cell that can divide to produce more similar cells, some of which will differentiate
• Types of stem cells

  • Embryonic stem cells
  • Adult stem cells
  • Meristems in plants
• Diffusion

  The spreading out of particles in a solution or gas, resulting in net movement from higher to lower concentration
• Substances can move across cell membranes by diffusion if they are small enough, like oxygen, glucose, amino acids, and water
• Diffusion in the body

  • Oxygen and carbon dioxide in gas exchange
  • Urea from liver to kidneys for excretion
• Factors affecting diffusion rate

  • Concentration gradient
  • Temperature
  • Surface area
  • Thickness of membrane