B: Lipids

Question 1

Five common classes of lipids in cell

Answer 1

Fatty acids
Triacylglycerols
Phospholipids
Glycolipids
Sterols

Question 2

Properties of unsaturated fatty acids

Answer 2

lower melting temperature, liquid at room temperature

Question 3

Properties of saturated fatty acids

Answer 3

more solid at room temperature

Question 4

Essential fatty acids:

Answer 4

Group of polyunsaturated fatty acids (PUFA) that cannot be synthesised by humans and must be obtained from diet.

Question 5

Triglycerides

Answer 5

3 fatty acids covalently joined to glycerol through ester linkages.

Question 6

What do triacylglycerols do?

Answer 6

• Provide stored energy
• Stockpiled in adipocytes (fat cells): adipocytes contain lipases

Question 7

What do adipocytes do?

Answer 7

Adipocytes contain lipases: catalyse hydrolysis of triglycerides, releasing fatty acids for transport to sites where they are used for fuel.

Question 8

What are sterols?

Answer 8

Sterols are structural lipids in eukaryotic cell membranes. They are synthesised from isoprenes.
Made of 4 fused carbon rings (3 with 6Cs, 1 with 5Cs)

Question 9

Niemann-Pick disease:

Answer 9

• lysosomal storage disease caused by autosomal recessive genetic defect in gene for sphingomyelinase.
• Results in a build up on sphingomyelin in brain, spleen, liver and lungs.

Question 10

Tay-Sachs disease

Answer 10

• lysosomal storage disease.
• Progressive deterioration of nerve cells + mental and physical capabilities.
• Autosomal recessive,
• build up of gangliosides in brain due to mutations in HEXA gene that codes for hexosaminidase A enzyme that catalyses degradation of gangliosides.

Question 11

Battens disease

Answer 11

• Due to a build up of lipofuscins
• Defect in CLN3 gene that codes for battenin protein

Question 12

Sphingolipids

Answer 12

Phospholipids/ glycolipids with a sphingosine backbone.