Phospholipids

• What do lipids contain?


  carbon, hydrogen, oxygen
• Are lipids soluble in water?

  No
• Why are lipids insoluble?

  They re not polar
• What are lipids soluble in?

  Alcohol
• What are the three most important lipids in living things?

  triglycerides, phospholidpids, and steroids
• What type of molecules are triglycerides, phospholidpids, and steroids?

  Macromolecules
• What are triglycerides composed of?

  1 glycerol and 3 fatty acids
• What are fatty acid that can't be made in our bodies and have to be ingested called?

  Essential fatty acids
• What is the structure of glycerol?

  Three carbon backbone with an alcohol (-OH) attached to each carbon (total of 3 -OH)

  
• What is the structure of a fatty acid?

  They carboxylic acid groups (COOH) and a variable 'R' group

  
• What makes a fatty acid an acid?

  It has a carboxyl group that can ionise to H+ and COO-
• What is a saturated fatty acid?


  One without double bonds.

  
• What is an unsaturated fatty acid?


  One with double bonds.

  
• What is a monounsaturated fatty acid?

  fatty acid with one double bond
• What is a polyunsaturated fatty acid?

  fatty acid with two or more double bonds
• How does the double bond affect the fatty acid?

  Causes a kink that pushes the molecules apart slightly which makes them more fluid
• How does a higher number of unsaturated fatty acids effect the melting point?

  Lowers melting point
• What type of fatty acid is in animals?

  Saturated
• How does a triglyceride form?

  A condensation reaction between the -COOH group of the fatty acids and the OH of the glycerol
• What are the products of a reaction between glycerol and 3 fatty acids?

  Water and a triglyceride
• What is the bond between fatty acids and glycerol called?

  Ester bond
• What are the 5 functions of lipids?

  Energy source, energy store, insulation, buoyancy, protection
• How do lipids act as an energy source?

  Can be broken down in respiration to generate energy and release ATP by hydrolysing the ester bonds and then the glycerol and fatty acids are completely broken down into carbon dioxide and water
• How do lipids act as an energy store?

  Because they are insoluble in water they can be stored without effecting the water potential of the cell
• How do lipids act as insulation?


  Adipose tissue is a storage location for lipids in whales (blubber) acting as a heat insulator. Lipid in nerve cells act as an electrical insulator
• How do lipids help with buoyancy?

  Because fat is less dense than water, it is used by aquatic animals to help them float
• How do lipids help with protection?

  Humans have fat around delicate organs such as the kidneys to act as a shock absorber. The peptidoglycan cell wall of some bacteria is covered in a lipid rich outer coat
• What is the structure of a phospholipid?

  glycerol, two fatty acids, and a phosphate group

  
• What sort of reaction forms a phospholipid?

  Condensation
• What type of bond is there between a phosphate group and a glycerol in a phospholipid?

  Ester bond
• What number of carbon atoms are there usually in the fatty acids in phosphlipids?

  An even number, often 16 or 18 (often one is saturated and the other isn't)
• How do phospholipids interact with water molecules?

  Hydrophillic head and hydrophobic tails
• What type of molecule is a phospholipid?

  amphipathic
• What usage of lipid normally means its amphipathic?

  membrane lipids
• How do phospholipids react when in contact with water?

  Tails stick up with heads forming layer on surface or might form a micelle (ball with heads on outside tails on inside)

  
• what structure do phospholipids form when forming a membrane?

  A bilayer

  
• What gives a phospholipid membrane bilayer its stability?

  The individual phospholipids are free to move around in their layer but will not move to any position that exposes the hydrophobic tails
• What allows the membrane to be selectively permeable?

  It is only possible for small, non-polar molecules to move through the bilayer
• What is cholesterol?


  A steroid alcohol (or sterol)
• What is a sterol?

  A type of lipid that is not made from glycerol or fatty acids