lipids

Question 1

what are the two types of lipids

Answer 1

fats – solid lipids (RTP)

oils – liquid lipids (RTP)

Question 2

what are some important properties of lipids?

Answer 2

non-polar molecules

electron in orbitals that form the bonds are more evenly distributed

no positive or negatively charged areas within the molecule

therefore is insoluble in water

Question 3

what’s another word for lipids?

Answer 3

macromolecules

not built up by monomers

Question 4

how is a triglyceride formed?

Answer 4

1 glycerol (an alcohol)

3 fatty acids (carboxylic acid)

both have hydroxyl group which interact

forms three water molecules + ester bonds between the fatty acids and the glycerol

Question 5

what is required to hydrolyse triglycerides

Answer 5

three water molecules

Question 6

what is the difference between saturated fatty acids and unsaturated fatty acids (with double bonds)?

Answer 6

presence of double bonds cause molecule to kink/bend

now the particles cannot pack together closely

causes the molecule to be a liquid

Question 7

what type of triglyceride is healthier to have in humans?

Answer 7

unsaturated triglyceride

Question 8

what’s a phospholipid

Answer 8

modified triglyceride that contains phosphorus

Question 9

what is the property of a phospholipid?

Answer 9

surface active agent (surfactant)

amphipatic structure

forms a layer on the surface of water with the tail (hydrophobic) sticking out the water

Question 10

describe a bilayer in terms of phospholipids

why is this important

Answer 10

forms a bilayer structure where the tails point towards the centre of the sheet protected by the phosphate head

key role in forming cell membranes

because they’re able to separate aqueous environments in which cells usually exist from the aqueous cytosol within cells

Question 11

what’s a sterol?

Answer 11

complex alcohol molecules based on 4-carbon ring structure with a hydroxyl group at one end

hydroxyl group is hydrophilic
rest of the molecule is hydrophobic

Question 12

name an example of a sterol

Answer 12

cholesterol

made primarily by liver and intestines

role in formation of cell membranes

positioned between the phospholipids where hydroxyl is at the periphery of the membrane which adds stability to cell membranes and regulates fluidity

Question 13

what are the roles of lipids?
(list 8)

Answer 13

membrane formation

hormone production

electrical insulation

waterproofing

long-term energy storage
stored under the skin and around vital organs

thermal insulation
reduces heat loss

cushioning
protect vital organs

buoyancy for aquatic animals

Question 14

describe the test for lipids

Answer 14

sample mix with ethanol

mix solution with water and shake

positive result – white emulsion layer at top of solution