1.2 lipids

Question 1

what are lipids used for?

Answer 1

-form cell membranes
-used as an energy store

Question 2

are lipids soluble?

Answer 2

no, only in alcohols

Question 3

what are lipids made up of?

Answer 3

glycerol and three fatty acids

Question 4

how many types of fatty acids are there?

Answer 4

2
-unsaturated
-saturated

Question 5

saturated lipids

Answer 5

• found in animal fats
• solid at room temperature
• don’t contains carbon-carbon double bond

Question 6

monosaturated and polysaturated lipids

Answer 6

-found in plants
-liquid at room temp (due to kinks)
-one double bond or multiple double bonds
-melt at lower temperatures due to weaker intermolecular forces

Question 7

what bonds are formed between glycerol and fatty acids?

Answer 7

ester

Question 8

how is an ester bond formed?

Answer 8

-condensation reaction occurs
- 3 molecules of water are removed called esterification

Question 9

what is the role of lipids in energy storage?

Answer 9

-contain many carbon-hydrogen bonds and little oxygen
-when oxidised in respiration, carbon dioxide and water are the ultimate products
-this can be used to make lots of ATP
-insoluble in water so don’t interfere with water based reactions in the cytoplasm (water potential)

Question 10

what is the role of lipids in waterproofing?

Answer 10

-they are hydrophobic
(eg: feathers or waxy cuticle on plants)

Question 11

what is the role of lipids in insulation?

Answer 11

-myelin sheath make electrical impulses travel faster
-insulate animals against heat loss
-very low density so body fat helps us float

Question 12

when are phospholipids formed?

Answer 12

-when one of the fatty acids of a triglyceride is sustituted by a phosphate group
-the phosphate heads are hydrophilic and the tails are hydrophobic which means they either form a bilayer or a micelle