Lipids

• What are lipids?


  Organic molecules characterized by low solubility in water (hydrophobic)
• What are the biological functions of lipids?

  Storage of energy , membrane structure , cofactors for enzymes , signalling molecules , pigments , antioxidants , insulation from environment , water repelant
• What are the classification of lipids?

  do not contain fatty acids: Cholesterol , terpenes

  
  

  Contain fatty acids- storage( triglycerols) and membrane (phospholipids , glycolipids)
• What are the characteristics of fatty acids?

  Carboxylic acids with hydrocarbon chains containing between 4-36 carbons , amphipatic , low solubility , unbranched
• What are the different types of fatty acids?

  Saturated: no double bonds

  Monounsaturated: One double bond

  Polyunsaturated: more than one double bond
• What does oleic acid look like (cis-9-octadecenoic acid)

  
• What does eicosapentaenoic acid look like?

  
• What does lauric acid look like?

  
• What does myristic acid look like?

  
• What does palmitic acid look like?

  
• What does palmitoleic acid look like?

  
• What does Stearic Acid look like?

  
• What does linoleic acid look like?

  
• What does linolenic acid look like?

  
• What does arachidic acid look like?

  
• What does arachidonic acid look like?

  
• What does tetracosanoic acid look like?

  
• What is the conformation of fatty acids?

  Saturated- extended conformations

  
  

  Double bonds in natural unsaturated fatty acids are commonly in cis configuration, which kinks the chain
• What is the trend of solubility and melting point of fatty acids?

  Solubility decreases as the chain length increases

  
  

  Melting point decreases as chain length decreases and number of bonds increase
• How are fatty acids arranged?

  Saturated - ordered so extensive favourable interactions

  
  

  Unsaturated- less ordered due to kink so less extensive favorable interactions and require less energy to disrupt
• What is the structure of triacylglycerols (TAG)

  3 fatty acids bound to an alcohol of a glycerol molecule by ester linkage , non polar

  
• What are the characteristics of TAGs

  Majority of fatty acids in body are found in this form , solids are fats , liquids are oils , primary storage form , less soluble in water than fatty acids due to the lack of charged carboxylate groups , less dense than water
• What are the advantages of using fats as fuel storage?

  Fatty acids carry more energy per carbon as they are more reduced , carry less water per gram as nonpolar , for long term energy needs
• What are the characteristics of trans fatty acid?

  formed by partial hydrogenation of unsaturated fatty acids (increase shelf life) , trans double bonds allows a fatty acid to adopt an extended conformation , trans fatty acids can pack morfe regularly , high MP , unhealthy
• What are the characteristics of waxes?

  esters of long chain saturated and unsaturated fatty acids with long chain alcohols , insoluble and have high melting points , storage , protection , waterproofing
• What are the characteristics of membrane lipids?

  contain polar head groups and non polar tails , diversification from modifying backbone , changing fatty acid and head groups , properties of head groups determine the surface properties of membranes
• What are the characteristics of glycerophospholipids?

  Primary constituents of cell membranes, two fatty acids form ester linkages with the first and second hydroxyl groups of glycerol , head group is charged at physiological ph , unsaturated fatty acids are commonly found connected to C2 , highly polar phosphate group maybe further esterified by an alcohol
• What are characteristics of ether lipids?


  Common in vertebrate heart tissue , found in some protozoa , resistance to cleavage
• What are the characteristics of sphingolipids?

  Bakcbone of sphingolipids is not glycerol , backbone of sphingolipids is a long chain amino alcohol sphigosine m fatty acid is joined via amide linkage , polar head is connected by a glycosidic or phosphodiester linkage , sugar containing glycosphingolipids are found in outer face of plasma membranes
• What are the characteristics of sphingomyelin?

  Ceramide (sphingosine + amide linked fatty acid_ + phosphocholine attached to alcohol , sphingomyelin is abundant in myelin sheath that surrounds some nerve cells
• How does glycosphingolipids relate to blood groups?

  blood groups are determined by type of sugars located on head groups , structure of sugar is determined by expression of specific glycosyltransferases