lipids

Question 1

elements in lipids?

Answer 1

C H & O

Question 2

what are fats?

Answer 2

solid lipids at room temp

Question 3

what are oils?

Answer 3

liquid lipids at room temp

Question 4

are lipids polar?

Answer 4

no - electrons in outer orbitals that form bonds are more evenly distributed than in polar molecules

Question 5

why are lipids non-polar?

Answer 5

electrons in outer orbitals that form bonds are more distributed than in polar molecules

Question 6

“lipid” definition

Answer 6

large complex macromolecules built from repeating units made of C H & O

Question 7

“macromolecule” definition

Answer 7

large complex molecules made form repeating units

Question 8

triglyceride structure

Answer 8

1 glycerol + 3 fatty acids

Question 9

what group is glycerol?

Answer 9

alcohols

Question 10

what group are fatty acids?

Answer 10

carboxylic acids

Question 11

what are fatty acids made of?

Answer 11

carboxyl group + hydrocarbon chain

Question 12

what reaction is the formation of triglyceride?

Answer 12

condensation reaction: esterification

Question 13

what bonds between glycerol & fatty acids are formed and how?

Answer 13

ester bonds ; hydroxyl groups on both react removing water (1H from glycerol + OH from fatty acids)

Question 14

triglyceride general formula?

Answer 14

CH2 O CH2 (CH2)n CH3

Question 15

“saturated” meaning

Answer 15

no double bonds between carbons bc all carbons form max bonds with hydrogen

Question 16

“unsaturated” meaning

Answer 16

double bonds present between some carbon atoms bc not all have max hydrogen bonds

Question 17

“monounsaturated” definition

Answer 17

only one double bond present between carbon atoms

Question 18

“polyunsaturated” definition

Answer 18

2+ double bonds between carbon atoms

Question 19

why are oils liquid at room temp?

Answer 19

• double bonds = molecule kinks and bends
• can’t pack close together
• liquid rather than solid = oils not fats

Question 20

triglycerides in plants?

Answer 20

unsaturated + healthier for human diet than saturated

Question 21

what can excess saturated fat in diet lead to?

Answer 21

CHD / obesity = strain on heart

Question 22

elements in phospholipids?

Answer 22

C H O & P

Question 23

“phospholipids” definition

Answer 23

modified triglycerides containing C H O & P

Question 24

where are phosphate ions found?

Answer 24

cytoplasm of every cell

Question 25

phosphate ions characteristics?

Answer 25

PO4 3- have extra electrons = neg charge = soluble in water

Question 26

phosphate ion charge?

Answer 26

PO4 3-

Question 27

phospholipid structure?

Answer 27

one of triglyceride fatty acid chains —> phosphate group

Question 28

are phospholipid heads non-polar?

Answer 28

**NO - THEY’RE CHARGED**

Question 29

what hydro are phospholipid heads?

Answer 29

hydrophilic ; charged = interact with polar water

Question 30

are phospholipid heads polar?

Answer 30

no

Question 31

are phospholipid tails polar?

Answer 31

no ; non-polar

Question 32

what hydro are phospholipid tails? why

Answer 32

hydrophobic = repelled by water

Question 33

what do phospholipid tails interact with?

Answer 33

mix with fats not water

Question 34

what do phospholipid heads interact with?

Answer 34

water

Question 35

how do phospholipids interact with water?

Answer 35

- layer on the surface - heads in water and tails sticking out = surface active agents (surfactants)

Question 36

phospholipid bilayer structure?

Answer 36

- tails pointed inwards away from water - heads outside interacting with water

Question 37

what do phospholipids help form in cells?

Answer 37

cell membranes

Question 38

how are phospholipids useful in cells?

Answer 38

- cell membranes - separate aqueous cell environment OUTSIDE from aqueous cytosol IN cells

Question 39

what group are sterols?

Answer 39

steroid alcohols

Question 40

are sterols lipids?

Answer 40

yes but NOT oils or fats

Question 41

sterol structure?

Answer 41

complex alc molecules - 4 carbon ring structure - hydroxyl group on one end

Question 42

sterol characteristics?

Answer 42

dual hydrophilic (polar hydroxyl group) & hydrophobic (rest of molecule)

Question 43

where is cholesterol made?

Answer 43

in the liver & intestines

Question 44

what is cholesterol used for?

Answer 44

positioned between phospholipids in bilayer with hydroxyl groups at periphery of membrane

Question 45

why is cholesterol useful?

Answer 45

between phospholipids = stability to membrane +regulates fluidity by keeping fluid at low temps + not too fluid at high temps

Question 46

what is made from cholesterol

Answer 46

- vitamin D - steroid hormones - bile

Question 47

biological roles of lipids?

Answer 47

- membrane formation + hydrophobic barriers - hormone production - electrical insulation for impulse transmission - waterproofing - long term energy storage

Question 48

where are lipids stored in the body?

Answer 48

under the skin and around vital organs

Question 49

benefits of lipids under the skin?

Answer 49

- thermal insulation eg. penguins, seals - cushioning (protects vital organs eg. heart kidney) - buoyancy in aquatic animals (whales)

Question 50

what is the test for lipids called?

Answer 50

emulsion test

Question 51

describe the emulsion test?

Answer 51

1. mix sample with ethanol 2. mix this with water and shake 3. white emulsion forms if lipid present

Question 52

positive emulsion test result?

Answer 52

white emulsion layer on top

Question 53

negative emulsion test result?

Answer 53

solution remains clear