Lipids

Question 1

Formation of ester bond

Answer 1

to form a triglyceride, 3 non-polar hydrophobic hydrocarbon chains joined to glycerol backbone via formation of 3 ester linkages via condensation reaction with a removal of 3 H2O

Question 2

properties of glycerol and fatty acids

Answer 2

• glycerol has 3 hydrophilic hydroxyl groups which can form hydrogen bonds with water, soluble in water
• fatty acids have charged COO- group which can interact with water –> soluble in water

Question 3

structure and properties of triglyceride

Answer 3

• 3 non-polar hydrophobic hydrocarbon chains with glycerol backbone via ester linkages
• long non-polar, hydrophobic hydrocarbon chains of triglyceride
  1. cannot form hydrogen bonds with water, hence triglycerides are insoluble in water and do not affect wpt
  2. have high proportion of C-H bonds from which energy in the form of ATP and metabolic water can be released during oxidation

Question 4

roles of triglycerides

Answer 4

• thermal insulation
• buoyancy
• protective layer around delicate internal organs
• reservoir for storage of fat soluble vitamins
• insoluble in water, does not affect wpt
• compact energy store because it can store twice as much. energy on oxidation compared with equivalent mass of carbs, higher proportion of C-H bonds and lower proprotion of O atoms, more energy released in the form of ATP during oxidation

Question 5

structure and properties of phopsholipids

Answer 5

• each phospholipid consists of a hydrophilic charged phosphate head, glycerol backbone and two hydrophobic, non-polar hydrocarbon chains
• phosphate to glycerol: phosphoester linkage, glycerol to tails: ester linkage
• amphipatic
• can form bilayers
• major component of membranes
• unsaturated hydrocarbon chains with kinks can help to prevent close packing of phospholipids, resulting in greater fluidity of the membrane as there are fewer hydrophobic interactions btw hydrocarbon chains of the phospholipids
• membranes with long hydrocarbon chains have higher melting point than membranes with short hydrocarbon tails because of more hydrophobic interactions, larger transient pores
• membranes with more kinks have lower melting point than membranes with fewer kinks, greater space between the phospholipids, harder to freeze