Lipids

Question 1

State the elements present in lipids (and the additional element needed to make phospholipids). (F

Answer 1

• Carbon
• Hydrogen
• Oxygen
• • Phosphorous ( phospholipids)

Question 2

Define the term “macromolecule”. (F)

Answer 2

Large complex molecules with a large molecular weight.

Question 3

State the 3 categories of lipids (or lipid derived molecules).

Answer 3

• Triglycerides
• Phospholipids
• Cholesterol

Question 4

State the components of a triglyceride. (F)

Answer 4

• glycerol

- 3 fatty acid chains

Question 5

Describe the difference between saturated, monounsaturated and polyunsaturated fatty acids/triglycerides. (F)

Answer 5

• saturated only has C-C single bonds
• monounsaturated has one C=C double bond
• polyunsaturated has two or more C=C double bonds

Question 6

Explain why saturated triglycerides tend to be solid (fats) at room temperature whereas unsaturated triglycerides tend to be liquid (oils).

Answer 6

Saturated triglycerides only have C-C bonds, so can fit together more compactly and are solid at RTP.

Unsaturated triglycerides also have C=C bonds, which cause kinks in the chain so it cannot fit together compactly and are liquid at RTP.

Question 7

Describe and explain how the melting point of a triglyceride would correlate with the length of the fatty acids it contained (S+C).

Answer 7

The longer the fatty acid chain, the higher the melting point. There are more intermolecular forces present, so more energy is required to break them.

Question 8

State the difference between the triglycerides found in non-fish animals and those in plants and fish.

Answer 8

Non-fish animals have saturated triglycerides.

Plants and fish have unsaturated triglycerides.

Question 9

Describe the basic structure of a phospholipid.

Answer 9

• glycerol
• phosphate head
• 2 fatty acid chains

Question 10

State the property that each end of the phospholipid has. (F)

Answer 10

Polar.

Question 11

Describe the difference between a triglyceride and a phospholipid.

Answer 11

A triglyceride has 3 fatty acid chains whereas a phospholipid has 2 fatty acid chains and a phosphate group.

Question 12

Name the bond that holds the building blocks of a triglyceride together. (F)

Answer 12

Ester bond

Question 13

State the names of the reaction that forms triglycerides and the reaction that breaks them apart. (F)

Answer 13

• condensation

- hydrolysis

Question 14

Explain how an ester bond is formed between glycerol and a fatty acid.

Answer 14

The -H on the glycerol and the -OH on the fatty acid form a water molecule, leaving an ester bond.

Question 15

State the number of water molecules produced in the production of one triglyceride.

Answer 15

3

Question 16

Describe the structure of sterols/cholesterol.

Answer 16

• 4 carbon rings

- hydroxyl group at one end

Question 17

List the functions of triglycerides (5 functions) and relate these functions to the properties of the molecules.

Answer 17

• thermal insulation: prevent heat loss because of high energy bonds
• buoyancy: low density
• waterproofing: hydrophobic so repel water
• long term energy storage: lots of high energy C-H bonds
• electrical insulation: does not conduct electricity

Question 18

List the functions of phospholipids (2 functions) and relate these functions to the properties of the molecules.

Answer 18

• membrane formation: hydrophilic “head” and hydrophobic “tail”
• surfactant: hydrophilic “head” and hydrophobic “tail”

Question 19

List the functions of cholesterol (2 functions) and relate these functions to the properties of the molecules.

Answer 19

• membrane formation

- manufactures Vitamin D, steroid hormones and bile

Question 20

Explain why triglycerides store more energy per gram than carbohydrates.

Answer 20

Triglycerides have more C-H bonds than carbohydrates.

Question 21

Explain how phospholipids form a membrane.

Answer 21

The phosphate “head” go on the outside, and the fatty acid “tails” go on the inside.

Question 22

Describe how the presence of cholesterol affects the properties of cell membranes.

Answer 22

Adds stability and regulates fluidity by keeping them fluid at low temperatures and preventing them from becoming too fluid at high temperatures.