Lipids

Question 1

Lipids

Answer 1

Molecules including fats, oils and cholesterol. They are used for energy storage (2x more energy than carbohydrates), insulation (slow conductors of heat), cellular membranes, waterproofing (e.g. wax, which is insoluble in water) and hormones. Oils are liquids at room temperature; fats are solid

Question 2

Lipid creation

Answer 2

Lipids are made by attaching fatty acids to glycerol in a condensation reaction. The three ester bonds in a triglyceride are formed from glycerol and the fatty acids.

Question 3

Saturation

Answer 3

Molecules in which all the carbon atoms are bonded, resulting in a straight chain. In unsaturated molecules, C=C bonds in the tails mean they cannot pack together, and are liquid at room temperature

Question 4

Emulsion test for lipids

Answer 4

Add 4ml of ethanol to 2ml of sample in a grease free boiling tube. Shake thoroughly, then add 4ml of water and shake gently. The fluid will become cloudy

Question 5

Fluid mosaic model

Answer 5

Phospholipid molecules can move relative to each other in the membrane, and embedded proteins, varying in size, shape and pattern, like tiles in a mosaic

Question 6

Phospholipid bilayer

Answer 6

A bilayer of lipids composed of phospholipids, with cholesterol embedded for stability. The phosphate heads are hydrophilic, while the fatty acid chains are hydrophobic. The water inside and outside the cell causes the bilayer to be formed

Question 7

Extrinsic proteins

Answer 7

Extrinsic proteins occur on the surface or partially embedded in the membrane. They act as mechanical support, as receptors for molecules such as hormones and as identifiers (antigens)

Question 8

Intrinsic proteins

Answer 8

Intrinsic proteins span the membrane. They act as carriers for the transport of water-soluble material, or as enzymes