Topic 1a- Biological molecules- Lipids

Question 1

What type of bond is made from a condensation reaction between glycerol and a fatty acid molecule?

Answer 1

Ester bond

Question 2

Describe how you would test for lipids in a solution

Answer 2

Emulsion test
1) Shake test substance with ethanol for about a minute so that it dissolves, then pour solution into water.
2) Any lipid will show up as a milky emulsion.
3) The more lipid there is, the more noticeable the milky colour will be.

Question 3

Triglycerides have a hydrophobic tail. Explain how this feature of a lipid is important for it’s function.

Answer 3

The hydrophobic tails force them to clump together in the cytoplasm as insoluble droplets. This means they can be stored in cells, as a source of energy, without affecting the cell’s water potential.

Question 4

Cell membranes contain phospholipids.
1) Describe the structure of a phospholipid.
2) Explain the difference between a saturated fatty acid and an unsaturated fatty acid.

Answer 4

1) Two fatty acid molecules and a phosphate group attached to one glycerol molecule. TRIGLYCERIDES HAVE 3 FATTY ACIDS
2) Saturated fatty acids don’t have any double bonds between their carbon atoms. Unsaturated fatty acids have one or more double bonds between their carbon atoms.