Biological Molecules: Triglycerides

Question 1

Triglycerides Formation

Answer 1

• Formed by the condensation of one molecule of glycerol and three molecules of fatty acid
• Fatty acids
• Can be saturated or unsaturated
• Have long hydrocarbon ‘tails’ that are hydrophobic, making triglycerides insolube in water

• A condensation reaction between glycerol and a fatty acid (RCOOH) forms an ester bond (cOc)
- The R-group of a fatty acid may be saturated or unsaturated

Question 2

Saturated Triglycerides

Answer 2

• Saturated - no C=C bonds

• Saturated triglycerides are commonly known as fats
• Solid at room temperature

• C-C bonds mean fatty acid tails don’t bend

• More compact than unsaturated triglycerides
• Stronger intermolecular forces than unsaturated triglycerides
• Particles are more tightly packed and have stronger intermolecular forces - rigid and therefore, solid at room temperature

Question 3

Unsaturated Triglycerides

Answer 3

• Unsaturated - at least one C=C bond

• Unsaturated triglycerides are commonly known as oils
• Liquid at room temperature

• C=C bonds mean fatty acid tails bend

• This pushes other unsaturated triglycerides further away in the cell - less compact
• More space between unsaturated triglycerides mean intermolecular forces are weaker
• Particles can flow and have weaker intermolecular forces - liquid at room temperature

Question 4

Roles of Triglycerides: Respiration

Answer 4

• Triglycerides can be hydrolysed into glycerol and fatty acids, which are also used in respiration
• Water - produced from respiration, triglycerides provide good source of water for metabolic reactions

Question 5

Roles of Triglycerides: Energy Store

Answer 5

• Triglycerides provide the most energy per unit of mass of any storage molecule

• Contain a lot of chemical energy from large number of carbon hydrogen bonds within fatty acid tails
• Useful for animals, reduces the mass that must be carried around

• Insoluble

• Large and non-polar molecules, hydrophobic fatty acid tails
• Stored substance doesn’t dissolve
• They don’t affect the osmotic balance of cells in the body

Question 6

Other Roles of Triglycerides: Waterproofing, Insulation, Protection, Buoyancy

Answer 6

• Waterproofing - oils repel water so aquatic animals produce oil to waterproof their fur
• Insulation - fats are used by animals as thermal insulation
• Protection - fats are also used by animals to protect delicate organs e.g kidneys
• Buoyancy - fats are less dense than water so they aid in buoyancy for aquatic animals