Lipids

Question 1

What does lipids mean?

Answer 1

The term lipids cover fats and oils (triglycerides), steroids and sterols, and waxes.

Question 2

What are the main types of lipids?

Answer 2

Triglycerides and Phospholipids

Question 3

What are triglycerides?

Answer 3

The most common lipid is a triglyceride. They are stored in animals as fats and are stored at around 20 degrees Celcius.

Question 4

What are triglycerides made up of?

Answer 4

They are made up of a molecule of glycerol and three fatty acid molecules.

Question 5

What are saturated fatty acids?

Answer 5

Saturated fatty acids have only single bonds between carbon atoms.

Question 6

What are unsaturated fatty acids?

Answer 6

Unsaturated fatty acids have at least one double bond between carbon atoms.

Question 7

Properties and examples of saturated fatty acids:

Answer 7

• high melting point

- solid at room temperature

Question 8

Properties and examples of unsaturated fatty acids:

Answer 8

-lower melting point than their counterpart

Question 9

What is the test for lipids?

Answer 9

The emulsion tests for lipids such as triglycerides. You crush some of the test material, mix it thoroughly with ethanol and pour the solution into water. If its white lipids are present.

Question 10

What type of reaction creates a triglyceride?

Answer 10

A condensation reaction creates a triglyceride as a molecule of water is removed as each fatty acid joins a glycerol.

Question 11

What bond is formed between a glycerol and fatty acid?

Answer 11

An ester bond will be formed between a fatty acid and glycerol.

Question 12

What do fatty acids look like?

Answer 12

H   H    H  H  H
I      I     I    I     I
C - C - C - C - C
I      I     I    I     I
H    H   H  H   H

Question 13

Draw a glycerol

Answer 13

H
            I
   H  --  C  -- OH
            I
   H  --  C  -- OH
            I 
  H  --  C   --  OH
            I
           H

Question 14

What is a phospholipid?

Answer 14

Similar to a triglyceride but contains a phosphate group instead of one of the fatty acids

Question 15

Phospholipid structure

Answer 15

(Meller drawing) The tail is hydrophobic and the head (made of glycerole and phosphate) is hydrophilic

Question 16

What happens when phospholipids are mixed with water?

Answer 16

When mixed with water phospholipids arrange themselves in a double layer with their hydrophobic tails pointing inwards and their hydrophilic heads pointing outwards. This is called a phospholipid bilayer and forms the basis of membranes in and around cells.