As Biology - Biological Molecules - Lipids

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  • A triglyceride is made of one molecule of glycerol with three fatty acids attached to it
  • Fatty acid molecules have long tails made of hydrocarbons (carbon chains with hydrogen atoms branching off)
  • The tails are hydrophobic (water-repelling)
  • These tails make lipids insoluble in water
  • All fatty acids consist of the same basic structure, but the hydrocarbon tail varies.


  • The long hydrocarbon tails of the fatty acids contain lots of chemical energy - a load of energy is released when they're broken down. Because of these tails, lipids contain about twice as much energy per gram as carbohydrates.
  • They're insoluble, so they don't cause water to enter the cells by osmosis (which would make them swell). The triglycerides bundle together as insoluble droplets in cells because the fatty acid tails are hydrophobic - the tails face inwards, shielding themselves from water with their glycerol heads.

Formed by condensation reactions

  • Like carbohydrates, triglycerides are formed by condensation reactions and broken up by hydrolysis reactions.
  • Three fatty acids and…



* the hydro carbon chains are hydrophobic= phospholipids 3rd point

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