Lipids

Question 1

are lipids polar or non-polar?

Answer 1

non polar.

Question 2

are lipids soluble in water?

Answer 2

no as they are non polar.

Question 3

what is a macromolecule?

Answer 3

a large complex molecule that is not built from monomers.

Question 4

how is a triglyceride made?

Answer 4

combining one glycerol molecule with three fatty acids.

Question 5

what group of molecules is glycerol from?

Answer 5

alcohols

Question 6

what group of molecules are fatty acids from?

Answer 6

carboxylic acids.

Question 7

what is the reaction between glycerol and fatty acids called?

Answer 7

esterification (an example of a condensation reaction) three water molecules are removed.

Question 8

what are the bonds formed between glycerol and fatty acids called?

Answer 8

ester bonds.

Question 9

what is a saturated fatty acid?

Answer 9

a fatty acid chain wih no double bonds between carbon atoms.

Question 10

what is an unsaturated fatty acid?

Answer 10

a fatty acid chain with double bonds between some carbon atoms.

Question 11

what are the different types of unsaturated fatty acids?

Answer 11

monounsaturated - one double bond.

polyunsaturated - two or more double bonds.

Question 12

why are unsaturated fatty acids oils?

Answer 12

the presence of double bonds between carbon atoms makes the molecule kink. this means they cannot pack as closely together so they are liquid at room temperature rather than solid.

Question 13

what is a phospholipid?

Answer 13

modified triglycerides that contain phosphurus.

Question 14

why are phospholipid heads soluble in water?

Answer 14

phosphate ions are negatively charged so theyre soluble in water.

Question 15

how many fatty acid tails are in a phospholipid?

Answer 15

2

Question 16

what are sterols?

Answer 16

another type of lipid found in cells. complex alcohol molecules

Question 17

what are the roles of lipids?

Answer 17

• membrane formation
• hormone production
• electrical insulation for nerve transmission.
• thermal insulation to reduce heat loss.
• cushioning to protect vitaly organs.
• buoyancy for aquatic life.

Question 18

what is the chemical test for lipids?

Answer 18

the lipid emulsion test.

Question 19

how do you conduct the lipid emulsion test?

Answer 19

1. sample is mixed with ethanol.
2. solution is mixed with water and shaken.
3. if lipids are present a cloudy white emulsion will form on the top of the solution.

Question 20

what is food synergy?

Answer 20

the idea that nutrients do not work in isolation, but together.

Question 21

why is the data is food reports often flawed?

Answer 21

• people tend to underestimate how much they eat.
• different genetics respond to nutrients differently.