Lipids

• What is the most common type of lipid?

  Triglycerides
• What elements do lipids, like triglycerides, contain?


  Carbon, hydrogen, and oxygen
• Why are triglycerides insoluble in water?

  Because they are non-polar
• In which solvents are triglycerides soluble?

  Ethanol, chloroform, and ether
• How are triglycerides formed?

  By condensation reactions between glycerol and fatty acids
• What type of molecule is glycerol?

  Glycerol is a type of alcohol
• What functional group do fatty acids contain?

  • COOH group (carboxyl)
• What is released during the condensation reaction that forms triglycerides?

  Three molecules of water
• What is the bond formed between glycerol and fatty acids called?

  Ester bond
• How can an ester bond be broken?


  By hydrolysis
• What characterizes unsaturated fatty acids?

  They have double bonds between neighboring carbon atoms
• How do double bonds affect the melting point of fatty acids?

  They make fatty acids and lipids melt easier
• What is a monosaturated fatty acid?

  A fatty acid with only one double bond
• What is a polysaturated fatty acid?

  A fatty acid with two or more double bonds
• Why can't monosaturated fatty acids be packed tightly together?

  Because the double bond forms a kink
• What characterizes saturated fatty acids?

  They have no double bonds between neighboring carbon atoms
• What is the relationship between saturated fatty acids and heart disease?

  A diet high in saturated fatty acids is linked to heart disease
• What is the main cause of heart disease?

  Fatty deposits in the coronary arteries and high blood pressure
• What happens to lipids and proteins after food absorption in the small intestine?


  They combine to create lipoproteins
• What occurs if the diet is high in saturated fats?

  Lipoproteins build up, leading to fatty deposits in coronary arteries
• How does a diet high in unsaturated fats affect lipoproteins?

  The body makes more high-density lipoproteins
• What is the significance of the ratio of high-density lipoproteins to low-density lipoproteins?

  A higher ratio lowers the risk of cardiovascular diseases
• What is a phospholipid?

  A special type of lipid with one fatty acid tail replaced by a phosphate group
• Why is the phosphate group in phospholipids significant?

  It is polar and thus soluble in water
• What do phospholipids form in water?

  Micelles and bilayers
• What is the structure of the phospholipid bilayer?

  Polar phosphate heads point outwards, and hydrophobic tails point inwards
• What are the main differences between triglycerides and phospholipids?

  Triglycerides have 3 fatty acid tails, while phospholipids have 2 and a phosphate group
• How can lipids be tested for in a sample?

  By mixing with absolute ethanol and adding water to form an emulsion
• What indicates the presence of lipids in a sample?

  The formation of a cloudy white emulsion
• What is the energy reserve function of triglycerides?

  They contain more carbon-hydrogen bonds than carbohydrates
• How much energy does one gram of fat produce when oxidized compared to carbohydrates?

  About two times more energy
• Where is fat stored in animals?

  Under the skin and around organs
• Where is fat stored in plants?

  As oils in seeds
• What role does fat play as a thermal insulator?

  It reduces heat loss when stored under the skin
• What bonds do saturated fats contain?


  Single Carbon-Carbon bonds
• What bonds to unsaturated lipids contain?


  Only double Carbon-Carbon bonds