1.3 LIPIDS

Question 1

Describe

test for lipids

Answer 1

1. dissolve solid samples in ethanol
2. add equal vol. of water and shake
3. +ive result: milky white emulsion

Question 2

Describe

triglyceride formation

Answer 2

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

Question 3

Contrast

saturated and unsaturated fatty acids

Answer 3

saturated:
* single bonds
* straight-chain w/ many contact points
* high melting point = solid room temp
* animal fats

unsaturated:
* double C=C bonds
* kinked molecule w/ fewer contact points
* low melting point = liquid room temp
* plant oils

Question 4

Describe and explain

triglyceride structure and function

Answer 4

• high enery:mass ratio = high calorific value from oxidation (energy storage)
• insoluble hydrocarbon chain = no effect on water potention of cells & used for waterproofing
• slow conductor of heat = thermal insulation
• less dense than water = buoyancy of aquatic animals

Question 5

Describe

phospholipid structure

Answer 5

amphipathic molecule: glycerol backbone attached to 2 hydrophobic fatty acid tails & 1 hydrophilicpolar phosphate head

Question 6

Describe

phospholipid function

Answer 6

• forms phospholipid bilayer in water = component of membranes
• taills can splay outwards = waterproofing

Question 7

Compare

phospholipids and triglycerides

Answer 7

• glycerol backbone
• contain C,H,O
• formed by condensation reactions

Question 8

Contrast

phospholipids and triglycerides

Answer 8

phospholipids:
* fatty acids & 1 phosphate group attached
* hydrophilic head & hydrophobic tail
* used primarily in membrane formation

triglycerides:
* 3 fatty acids attached
* entire molecule molecule is hydrophobic
* used primaily as storage molecule

Question 9

Explain

why lipids aren’t polymers

Answer 9

not made from a small repeating unit, they’re macromolecules