1.2 - Lipids

Question 1

Name the 2 groups of lipid

Answer 1

• triglycerides
• phospholipids

Question 2

How are triglycerides formed?

Answer 2

condensation of 1 glycerol molecule and 3 fatty acid molecules

Question 3

How is an ester bond formed?

Answer 3

condensation reaction between glycerol and fatty acid

Question 4

Name the components of a phospholipid

Answer 4

1 phosphate, 1 glycerol, 2 fatty acids

Question 5

Describe the emulsion test for lipids

Answer 5

• add ethanol
• then add water and shake
• positive: white/milky emulsion
  NB: for control use water, final solution clear

Question 6

Function of triglycerides

Answer 6

• excellent energy store = fatty acid hydrocarbon tails
• hydrophobic fatty acid tails so repels water (insoluble) = doesn’t affect water potential of cells

Question 7

Function of phospholipids

Answer 7

• hydrophilic phosphate heads = interacts with water
• hydrophobic fatty acid tails = repel water
• so controls what passes through bilayer (plasma membrane)
• can form glycolipids with carbohydrates = cell recognition (receptors) on cell-surface membrane

Question 8

What is a saturated fatty acid?

Answer 8

only C-C bonds in hydrocarbon chain

Question 9

What is an unsaturated fatty acid?

Answer 9

at least one C=C bond in hydrocarbon chain

Question 10

What do phospholipids form when in contact with water?

Answer 10

micelles