2.1.2 - Lipids

Question 1

Lipids

Answer 1

• Organic molecules composed of C, H, O
• Macromolecules
• Non polar
• Fats : Solid lipids
• Oils : Liquid lipids

Question 2

Structure of triglycerides

Answer 2

• One molecules of glycerol and three fatty acids
• Glycerol is an organic alcohol which has three free hydroxyl groups(-OH)
• Fatty acids are organic acids that have a carboxyl group joined to a hydrocarbon tail

Question 3

Ester condensation reactions

Answer 3

A triglyceride is formed by joining one glycerol and three fatty acids through condensation reactions. An ester bond forms between the glycerol and fatty acids. Triglycerides contain three Ester bonds. Water is also formed

Question 4

Ester hydrolysis reaction

Answer 4

The hydrolysis of a triglyceride requires three molecules of water. This breaks the three ester bonds of the triglyceride molecule,forming glycerol and three fatty acids

Question 5

Saturated

Answer 5

• No double bonds present
• All Carbon atoms form the maximum number of bonds with hydrogen atoms
• Animals have more saturated fat

Question 6

Unsaturated

Answer 6

• Has at least one double bond
• The presence of a double bond causes the molecule to kink
• > Can’t pack closely together
• > Liquid at room temp
• Microorganisms and plants have more unsaturated fat

Question 7

Functions of triglycerides

Answer 7

• Respiration : Triglycerides are broken down into glycerol and fatty acids, which can then be used in respiration. They release a lot of energy due to large number of C-H bonds broken
• Energy storage : Can store the most energy per unit of mass of any storage molecule. Large and non-polar so insoluble in water
• Insulation : Reduce heat loss
• Buoyancy : Can help animals float
• Protection : Forms a layer around delicate organs

Question 8

Structure of phospholipids

Answer 8

• One glycerol, two fatty acids, one phosphate group
• Phosphate head : charged so will interact with water (hydrophilic)
• Fatty acid : non-polar so repelled by water (hydrophobic)
• The molecule is amphipathic - has both hydrophilic and hydrophobic parts
• Phospholipids form a bilayer

Question 9

Function of phospholipids

Answer 9

• The polar nature of the phospholipids cause them to form a bilayer
• The hydrophobic tails on the inside of the bilayer makes the cell membrane partially permeable
• The partial permeability allows the membrane to act as an electrical insulator

Question 10

Cholesterol

Answer 10

• Becomes positioned between the phospholipids in the bilayer
• This adds stability to cell membranes and regulates their fluidity
• Vitamin D, steroid hormones and bile are all manufactured using cholesterol

Question 11

Contains only the elements carbon, hydrogen and oxygen

Answer 11

• Triglyceride

- Cholesterol

Question 12

Insoluble in water

Answer 12

• Triglyceride
• Phospholipid
• Cholesterol

Question 13

Contains glycerol

Answer 13

• Triglyceride

- Phospholipid

Question 14

Contains ester bonds

Answer 14

• Triglyceride

- Phospholipid

Question 15

Contains fatty acids

Answer 15

• Triglyceride

- Phospholipid