1.7 Lipids

Question 1

What are lipids?

Answer 1

• class of molecules that do not include true polymers

Question 2

What is the size of lipids? Are they polar? (3)

Answer 2

• lipids are generally small in size
• hence they are not considered to be true a macromolecule
• lipids are non polar (hydrophobic)

Question 3

What are the three types of lipids, and name some of examples of them

Answer 3

1. Fats (saturated or unsaturated)
2. Phospholipids (part of cell membrane)
3. Steroids (estrogen, testosterone, cholesterol)

Question 4

What are fats composed of?

Answer 4

• glycerol and fatty acids

Question 5

What Is glycerol?

Answer 5

• classified as an alcohol (hydroxyl group 3’)

Question 6

What are fatty acids?

Answer 6

• long carbon chains (carboxyl group at one end)

Question 7

What linkage joins 3 fatty acids to glycerol? What is it?

Answer 7

Ester linkage, which is a bond between hydroxyl and a carboxyl group

Question 8

What is a saturated fatty acid? (2)

Answer 8

• no double bonds between carbons in the carbon chain

- therefore more hydrogen

Question 9

What is an unsaturated fatty acid?

Answer 9

• contains one or more double bonds

Question 10

What are phospholipids? (2)

Answer 10

• major components of cell membranes

- two fatty acids attached to glycerol and a phosphate

Question 11

Phospholipids assemble as a bilayer in water. Why? (4)

Answer 11

• hydrophobic tails
• Hydrophilic heads
• the phosphate group (-) is attracted to polar water molecules
• the fatty acids are neutral because equal sharing of electrons, so they are not attracted to water

Question 12

What are steroids?

Answer 12

• lipids that have four fused carbon rings

Question 13

What determines the type of steroid?

Answer 13

• unique groups attached to the ring determine the type of steroid
  Ex. Testosterone