Triglycerides & Phospholipids

Question 1

What are lipids?

Answer 1

They are not polymers and they all contain hydrocarbons e.g. triglycerides and phospholipids.

Question 2

What are triglycerides?

Answer 2

They are made of one glycerol molecule (an alcohol made of 3 carbons and 3 OH groups) and three fatty acids. The fatty acids are the hydrocarbon tails.

Question 3

What are the differences between saturated and unsaturated fatty acids?

Answer 3

Saturated fatty acids don’t have any carbon double bonds and tend to be solid at room temperature. Unsaturated fatty acids have carbon double bonds and tend to be liquid at room temperature.

Question 4

How are triglycerides formed?

Answer 4

They are formed by condensation reactions and an ester bond is formed between the fatty acids and glycerol, releasing a water molecule.

Question 5

What are some properties of triglycerides?

Answer 5

• They are used as long term storage molecules due to their insolubility.
• Their hydrocarbon tails contain lots of chemical energy which is released when broken down (double that of carbohydrates).

Question 6

What are miscelles?

Answer 6

They are made of triglycerides bundled together. The fatty acids tails face inwards to shield themselves from water because they are hydrophobic.

Question 7

What are phospholipids?

Answer 7

They are a type of lipid found in cell membranes. They are made from one glycerol molecule, two fatty acids (hydrophobic) and a phosphate group (hydrophilic) attached by ester bonds.

Question 8

What are some properties of phospholipids?

Answer 8

• They made phospholipid bi-layers, used in cell membranes, in order to control what enters and leaves the cell.
• The phospholipid heads (glycerol) are hydrophilic (loves water) and tails are hydrophobic so form a double layer where the heads face outwards and tails are internal.
• The bi-layer centre is made of hydrophobic tails so water-soluble substances can’t pass through it and the membrane acts as a barrier.