1.6 — lipids: introduction

Question 1

what are lipids?

Answer 1

biological molecule that contain the elements carbon, hydrogen and oxygen. lipids contain a much lower proportion of oxygen than other carbohydrates

Question 2

lipids are not made up of ____ _____ of monomers, meaning that are not considered ________. what are the missing terms?

Answer 2

long chains/polymers

Question 3

what are the roles of lipids? (5)

Answer 3

1. energy supply — lipids can be oxidised to provide energy to cells
2. structural components — phospholipids are used in cell membranes
3. waterproofing — insoluble lipids are used to form water resistant barriers
4. insulation — lipids can help retain heat or act as electrical insulators
5. protection — delicate organs are surrounded by a layer of fat

Question 4

what are most lipids made up of?

Answer 4

fatty acids combined with an alcohol (usually glycerol)

Question 5

what does the structure of a fatty acid contain?

Answer 5

a carboxylate group (-COOH) attached to a hydrocarbon chain (R group)

Question 6

what are the two types of fatty acid?

Answer 6

saturated and unsaturated

Question 7

what does saturated mean?

Answer 7

all carbon bonds are bonded to the maximum number of hydrogen bonds due to only consisting of single carbon-carbon (C-C) bonds

Question 8

what type of lipids have a higher melting point?

Answer 8

lipids that contain a saturated fatty acid

Question 9

what state are saturated fats usually at at room temp and what are they?

Answer 9

solid/fats

Question 10

what does unsaturated mean (and hoe does this affect the chain)?

Answer 10

all carbon bonds are not bonded to the maximum number of hydrogen bonds due to consisting of both single carbon-carbon (C-C) bonds, and at least one double carbon-carbon (C=C) bond. this causes a kink in the chain

Question 11

what type of lipids have a lower melting point?

Answer 11

lipids containing unsaturated fatty acids

Question 12

what state are unsaturated fats at room temperature and what are they?

Answer 12

liquid/oils

Question 13

what are the two types of unsaturated fatty acids?

Answer 13

monounsaturated and polyunsaturated

Question 14

what does a fatty acid being monounsaturated mean?

Answer 14

it contains one double carbon-carbon (C=C) bond

Question 15

what does a fatty acid being polyunsaturated mean?

Answer 15

it contains two or more double carbon-carbon (C=C) bonds

Question 16

what are the steps to find out whether a sample contains a lipid?

Answer 16

• place food sample into a test tube
• add 2cm³ of ethanol
• shake
• add 2cm³ of water
• if lipids present, a milky white emulsion will appear