Cell Membranes

Diffrent sections of cell membranes.

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  • Include waxes, sterols, fats and oils.
  • Fats are chemically triglycerides.
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  •  Saturated: Hard animal fats which are linked with heart disease. They are a chain of carbons molecules saturated with hydrogen.
  • Polyunsaturated: Vegetable fats/oils which are not linked with heart disease. Contain lots of double bond carbons. C=C.
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  • Made up of glycerol head joined to three fatty acids.
  • Made via condensation reaction between glycerol and a fatty acid meaning on molecule of water is removed (one molecule of water per fatty acid).
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  • One fatty acid on a triglyceride is replaced with a phosphate.
  • The phosphate changes the properties of the glycerol head. Making it soluble in water Hydrophilic.
  • The two remaining fatty acid tails are insoluble in water Hydrophobic.
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Fluid mosaic

  • Mosaic: The proteins are embedded in the phospholipid bi-layer.
  • Fluid: The proteins can make sideways movements in the phospholipid bi-layer.
  • Protein functions: Movement of materials across a membrane, active transport and facilitated diffusion.
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Facilitated diffusion

  • Movement down a concentration gradient.
  • Requires protein carriers in channels in the membrane.
  • Doesn't require energy in the form of ATP.
  • It's specific, the proteins are shaped to carry only one type of molecule.
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  • Movement of water through a partially permeable membrane.
  • The movement of water from a higher water potential to a lower water potential.
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Active transport

  • Movements of molecules against a concentration gradient.
  • Requires protein carriers in the membrane.
  • Requires energy from respiration in the form of ATP.
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Water potential

  • The ability of water to loose water
  • Pure water has a water potential of 0.
  • As you add solute the water potential becomes more negative.
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