Lipids

• What is a triglyceride?

  
  

  1 molecule of glycerol and 3 fatty acids bonded by ester bonds
• How Is an ester bond formed?

  
  

  In a condensation reaction, a hydrogen from the glycerol and a hydrogen and oxygen from the carboxyl group of the fatty acid join to form water. Then an ester bond forms between the remaining oxygen (from the glycerol) and a carbon (from the fatty acid) to form a monoglyceride.
• What is a monoglyceride?

  
  

  a molecule of glycerol joined to 1 fatty acid by an ester bond
• What is a phospholipid made up of?

  
  

  1 glycerol molecule bonded to 2 fatty acids by ester bonds. The 3rd fatty acid is replaced by a phosphate group.
• What are monomers?

  
  

  Smaller units from which larger molecules are made
• 3 examples of monomers

  Monosaccharides, amino acids and nucleotides
• What are polymers?

  
  

  Molecules made from a large number of monomers joined together
• What is the structure of a fatty acid ?

  
  

  carboxyl group and hydrocarbon tail (sometimes represented by 'R')
• Where does variation in fatty acids occur?

  
  

  in the hydrocarbon tail
• How does variation in fatty acids occur?

  
  

  - different lengths of chain

  - saturated (no C=C bonds)

  - unsaturated (has C=C bonds)
• What is a monounsaturated fatty acid?

  
  

  has 1 C=C bond
• What is a polyunsaturated fatty acid?

  
  

  has 2 or more C=C bonds
• Why is a lipid not a polymer?

  
  

  It is not made up of one singular monomer repeating
• What makes up the head of a phospholipid?

  
  

  Glycerol and phosphate group
• What is significant about the 'head"of a phospholipid ?

  
  

  Hydrophilic / water attracted/ dissolves in water
• What is significant about the fatty acid tail of a phospholipid?

  
  

  Hydrophobic / water repelled
• What cause a kink in phospholipid tails?

  
  

  double carbon bonds
• What happens the more kinks a phospholipid tail has?

  
  

  The molecules are harder to pack closely together and so they are less dense and have a lower melting point.
• Where are lipids synthesised?

  smooth endoplasmic reticulum
• What are phospholipids the main molecule in?

  cell membrane
• Are triglycerides soluble or insoluble in water ?

  Insoluble due to the fatty acid tail being hydrophobic