structure-function relationship of triglycerides

Question 1

how does having long fatty acid chains containing many C-C & C-H bonds in triglycerides allow it to be a good energy reserve?

Answer 1

• the long fatty acid chain will be broken into many molecules of acetyl-CoA
• the acetyl-CoA molecules will be oxidised during Krebs cycle to provide large amounts of energy during ATP synthesis

Question 2

how does having twice the number of C atoms per unit mass than carbohydrates allow triglycerides to act as efficient energy reserves compared to carbohydrates?

Answer 2

• for the same mass of molecule, 1 gram of triglyceride releases more energy than 1 gram of carbohydrates
• hence, for the same amount of energy stored, triglycerides have half the mass of carbohydrates
• this allows animals to keep their mass low for locomotion, and allow plant seeds to be kept small & light for dispersal by wind or animals

Question 3

how does having non-polar & large hydrophobic fatty acid chains allow for triglycerides to act as good storage molecules?

Answer 3

• it prevents triglycerides from diffusing out of cells
• additionally, it can also be stored in large amounts without affecting water potential of cells

Question 4

what structural adaptation of triglycerides allows it to act as an important source of metabolic water for desert animals?

Answer 4

• having more than twice the number of H atoms per unit mass than that of carbohydrates

Question 5

how do triglycerides provide buoyancy?

Answer 5

• triglycerides are less dense than water, allowing aquatic animals (eg. whales) to stay buoyant in water

Question 6

how do triglycerides allow for long-term energy reserves in cells?

Answer 6

• triglycerides are oxidised to provide energy only after carbohydrates (glucose & glycogen) are depleted, which is important to hibernating animals

Question 7

how do triglycerides act as a thermal insulator?

Answer 7

• triglycerides prevent excessive heat loss, which is important for mammals living in cold climates & aquatic animals

Question 8

how do triglycerides provide shock absorption?

Answer 8

• triglycerides cushion & protect delicate organs (eg. kidneys) in a layer of fats