1 Biological Molecules- Lipids

Question 1

What are 2 types of lipids?

Answer 1

Triglycerides and phospholipids

Question 2

Features of lipids?

Answer 2

Contain hydrogen, carbon and oxygen
Store energy

Question 3

How are triglycerides formed?

Answer 3

The condensation of one molecule of glycerol and three molecules of fatty acid

Question 4

How is an ester bond formed?

Answer 4

Through a condensation reaction with glycerol and a fatty acid (RCOOH)

Question 5

What is a saturated fatty acid R-group?

Answer 5

Has no double bonds between C atoms, fully saturated with H atoms

Question 6

What is an unsaturated fatty acid R-group?

Answer 6

One or more double bonds between C atoms
monounsaturated- 1 double bond
polyunsaturated- more than 1 double bond

Question 7

How are phospholipids formed?

Answer 7

The condensation of one molecule of glycerol with two molecules of hydrophobic, non-polar fatty acid
One fatty acid molecule, like in triglycerides, is replaced by a hydrophilic, polar phosphate group

Question 8

What are the functions of triglycerides?

Answer 8

Energy release- chemical energy is stored in the fatty acid hydrocarbon tails, so lots of energy is released when triglycerides break down
Repel water- insoluble in water due to hydrophobic fatty acid tails, so cell’s water potential isn’t affected. Water can’t enter the cell by osmosis and make it swell up
Form lipid droplets- as they are insoluble they crowd together as droplets, as the hydrophobic fatty acid tails face inwards

Question 9

What are the functions of phospholipids?

Answer 9

-Form bi-layer
-Main component of cell membranes, responsible for controlling what goes in and out of the cell. In membranes, the hydrophilic phosphate group faces the outside and the hydrophobic fatty acid tails face inwards in the bi-layer

Question 10

What is the food test for lipids?

Answer 10

Add ethanol to the food sample and shake. Then add an equal volume of water. A positive result is a milky white emulsion