1.3 lipids

Question 1

Describe how to test for lipids in a sample

Answer 1

1. dissolve solid samples in ethanol
   2.add an equal volume of water and shake
   3.positive result: milky white emulsion.

Question 2

how do triglycerides form?

Answer 2

condensation reaction between 1 molecule of glycerol & 3 fatty acids forms ester bonds.

Question 3

what’s the difference between saturated and unsaturated fatty acids?

Answer 3

saturated
-contains only single bonds
-solid at room temp
-straight chain molecules
-found in animal fats

unsaturated
-contains double bonds C=C
-liquid at room temp
-kinked molecule <
-found in plant oils

Question 4

relate the structure on triglycerides to their functions

Answer 4

-insoluble hydrocarbon chain = no effect on water potential & used for waterproofing

they cant mix in water and break down

Question 5

describe the structure of phospholipids

Answer 5

1 glycerol backbone, 2 hydrophobic fatty acid tails & 1 hydrophilic phosphate head

Question 6

describe the function of phopholipipds

Answer 6

-forms phospholipid bilayer in water = components of membranes

-tails splay outwards = water proofing

Question 7

compare phospholipids and triglycerides

Answer 7

• both have a glycerol backbone
  -both contain elements C,H,O
  -both formed by condensation reactions

Question 8

what’s different about phospholipids and triglycerides?

Answer 8

phospholipids
-2 fatty acid & 1 phosphate head
-hydrophilic head & hydrophobic tail
-used in cell membranes

triglycerides
- 3 fatty acid molecules
-entire molecule is hydrophobic
-used as a storage molecule

Question 9

are phospholipids and triglycerides polymers?

Answer 9

no: they aren’t made from a repeating unit