lipids

Question 1

what are the key properties of lipids?

Answer 1

• They are macromolecules, not polymers
• Non-polar molecules
• Insoluble in water
• Will dissolve in organic solvents, such as ethanol
• hydrophobic

Question 2

what are the 3 types of lipids and what are they made from?

Answer 2

• triglycerides = one glycerol molecule, 3 fatty acids
• phospholipids = one glycerol molecule, 2 fatty acids and a phosphate group
• sterols = 4 carbon rings and a hydroxyl group at one end, with hydrophobic and hydrophillic regions

Question 3

what is the main use of cholesterol in membranes?

Answer 3

• embedded within cell membranes to impact fluidity
• reduces fluidity at high temps
• increases fluidity at low temps

Question 4

what is the test for lipids?

Answer 4

emulsion test
- prepare food sample (must be liquid)
- add ethanol to a test tube of the sample and shake (use a bung)
- add the solution to a test tube of water
- if a white suspension/ cloudty white solution is formed, lipids are present