The fluid mosaic model

• Label these parts of the cell membrane

  A) phospholipid

  B) extrinsic/peripheral protein

  C) channel protein

  D) carrier proteins

  E) intrinsic/intergral proteins

  F) carbohydrate & glycoprotein

  G) glycocalyx

  
• Why do cells need membranes?

  -controls entry and exit of substances

  -contains the cell contents and organelles; compartmentalises individual cell processes

  -communication with external environment

  -site of chemical reactions

  -allows cell to change shape

  -transport and packaging within a cell
• What are cell membranes made of?

  Phospholipids: these make it impenetrable to water soluble substances

  Proteins: these provide passageways to water soluble substances and other molecules
• Lipids in the cell membrane are phospholipids. They are composed of a glycerol backbone, a phosphate head and two fatty acid tails. The fatty acid tails are non-polar, and the phosphate group is polar.
• What makes the cell membrane fluid?

  The phospholipid bilayer is not a fixed structure. The phospholipids are able to move: they can rotate on their axis, they can 'swap' places with the phospholipid next to them and the phospholipid directly opposite them. These movements increase the fluidity of the membrane.
• What are the different types of protein in the membrane?

  Passive and active carrier proteins, gated-channel proteins and channel proteins
• State the functions of membrane proteins.?

  -transport of substances in and out of the cell

  -cell signalling/recognition/receptors

  -enzyme systems