Lipids

Question 1

What are lipids?

Answer 1

Lipids are organic molecules mainly made up of two main types of lipid: triglycerides and phospholipids

Question 2

What are triglycerides?

Answer 2

Triglycerides are non -polar hydrophobic molecules

Question 3

What are the monomers of triglycerides?

Answer 3

Monomers of triglycerides are glycerol and fatty acid

Question 4

What composes a triglyceride?

Answer 4

A triglyceride is composed of three fatty acids attached to a glycerol molecule

Question 5

How is triglyceride formed?

Answer 5

Triglyceride is formed form three separate condensation reactions that occur between the glycerol molecule and the three fatty acids, forming three water molecules as waste

Question 6

What type of bond is formed from the condensation reaction in triglycerides?

Answer 6

Triglycerides form ester bonds

Question 7

What is the two way fatty acids can vary?

Answer 7

Fatty acids can vary in length and the fatty acid chain being saturated or unsaturated

Question 8

What is a saturated fatty acid?

Answer 8

A saturated fatty acid consists of no double bonds within their hydrocarbons

Question 9

What is an unsaturated fatty acid? What are the two different types?

Answer 9

An unsaturated fatty acid contains at least one or more double bonds within the hydrocarbons. The two possible types of hydrocarbon are mono or poly - unsaturated fatty acids

Question 10

What is a mono unsaturated fatty acid?

Answer 10

A fatty acid consisting of one double bond between the hydrocarbons

Question 11

What is a poly - unsaturated fatty acid?

Answer 11

A fatty acid that consists of two or more double bonds between its hydrocarbons

Question 12

Where does the ester bond form in triglycerides?

Answer 12

An ester bond forms between a hydroxyl (-OH) group on glycerol bonds joins with carboxyl (-COOH) group of the fatty acid

Question 13

Name some structural features of triglyceride that result in some of its properties:

Answer 13

1. Triglyceride has a large ratio of energy-storing carbon - hydrogen atoms. Which results in a lot of energy being stored in the molecule
2. Triglycerides are long and hydrophobic, making them insoluble - do not affect water potential and do not cause osmotic water uptake
3. Triglycerides are a metabolic water source. When they are oxidised water is released, allowing it to act as a source of water for animals in the desert

Question 14

What are phospholipids composed of?

Answer 14

Phospholipids are composed of a glycerol molecule, a phosphate group and two fatty acid chains

Question 15

How is the ester bond formed in phospholipids

Answer 15

The two fatty acids bond to the glycerol molecule through two condensation reactions to form the two ester bonds

Question 16

Describe the hydrophilic head

Answer 16

The hydrophilic head repels fats and attracts water since it is charged

Question 17

Why is the head of the phospholipid called hydrophilic?

Answer 17

The head is called hydrophilic because of the negative charge on the phosphate group

Question 18

What are the fatty acid chains described as?

Answer 18

Hydrophobic

Question 19

Why are the fatty acid chains described as hydrophobic?

Answer 19

The fatty acid chains repel water but will attract fats, mixing with them

Question 20

What do phospholipids form?

Answer 20

Phospholipids form a phospholipid bilayer membrane structure

Question 21

How are phospholipids positioned in water?

Answer 21

In water, phospholipids have their hydrophilic heads facing the water and their tails facing each other so they are not exposed to the water

Question 22

What are the similarities between phospholipids and triglycerides?

Answer 22

1. Both contain a glycerol molecule
2. Both may be attached to a mixture of saturated, monounsaturated and polyunsaturated fatty acids
3. Both contain the elements carbon, hydrogen and oxygen
4. Both are formed by condensation reaction