membranes and membrane transport

• how are phsopholipid bilayers formed

  a hydrophilic phosphate head bonds with 2 hydrophobic hydrocarbon tails
• what happens when phospholipids are placed in water

  the hydrophilic phosphate heads orient towards the water and the hydrocarbon tails orient away from the water
• what properties of the phospholipid bilayer allow it to form a barrier

  large molecules cannot pass through, polar molecules and ions cannot pass through
• what are two categories of membrane proteins

  integral and peripheral
• what are integral membrane proteins

  amphipathic, embedded in the phospholipid bilayer
• what are peripheral membrane proteins

  hydrophilic, attached to either surface of integral proteins, can be inside or outside the cell
• what are 2 types of transport proteins

  channel and carrier
• what are channel proteins 


  they form holes or pores where molecules can travel through
• what are carrier proteins

  they change shape to transport a substance across the membrane
• what is simple diffusion

  a type of membrane transport that involves particles passing directly between the phospholipids in the plasma membrane
• what are examples of molecules that move by simple diffusion

  oxygen and carbon dioxide
• what are some factors which effect the rate at which a substance diffuses across a membrane

  temperature, surface area, properties of the molecule
• what is facilitated diffusion

  when substances can only cross the phospholipid bilayer with the help of transport proteins
• what are the types of proteins that enable facilitated diffusion

  channel and carrier
• what are channel proteins

  A) channel protein

  B) phospholipid bilayer

  
• what are carrier proteins

  A) phospholipid bilayer

  B) carrier protein

  
• what is selective permeability

  the ability of the membrane to differentiate between different types of molecules
• how does ATP release energy

  it is hydrolysed
• what are glycoproteins

  cell membrane proteins that have a carbohydrate chain attached on the extracellular side (outside cells)
• what are glycolipids

  lipids with carbohydrate chains attached on the outside cells
• what do glycoproteins and glycolipids do

  the carbohydrate chain enables them to act as receptor molecules
• who outlined the fluid mosaic model of membranes

  singer and nicolson, 1972
• what does the fluid mosaic model describe cell membranes as

  fluid - proteins and phospholipids can move around within the layers

  mosaics - scattered pattern produces by the proteins within the layer
• what is the fluid mosaic model

  A) glycolipid

  B) glycoprotein

  C) cholesterol

  D) peripheral protein

  E) integral protein

  F) channel protein

  G) hydrophilic phosphate head

  H) hydrophobic fatty acid tail