methods of transport across cell membranes

• from hight to low concentration (untill equilibrium reached)

• hydrophobic (lipid- soluble) or small uncharged molecules

eg. oxygen/ carbon dioxide

• through phospholipid bilayer

• passive, no energy required

• from hight to low concentration (untill equilibrium reached)

• hydrophobic molecules or ions (large)

eg. Glucose

• through channel protiens and carrier protiens (via protiens that change shape)

• passive, no energy required

• a type of diffusion involving movement of free water molecules

• from hight to low concentration (untill equilibrium reached)

• through phospholipid bilayer

• passive, no energy required

• Agaisnt concentration gradient, low to high

eg. ions into root hairs, muscles and nerve cells

• through carrier proteins that change shape

• requires energy

• with or against a concentration gradient

• used for bulk transport of substances out of the cell, very large particles

eg. proteins, usually insulin, nuerotransmitters or polysaccharides

• not through membranes

• active energy is required

• vesicles fuse with the cell surface membrane, releasing their contents

• with or without a concentration gradient

• active, energy is required

• used for bulk transport of substances into the cell, very large molecules or particles

eg. cholesterol, bacteria by white blood cells

• vesicles are created from the cell surface membrane, bringing their contents into the cell