lipids

Question 1

what are the constituent molecules in a lipid and triglyceride

Answer 1

glycerol and fatty acid

Question 2

what are the differences between a triglyceride and a phospholipid

Answer 2

one of the fatty acid side chains is replaced by a phosphate group

Question 3

distinguish between a saturated and unsaturated fatty acid

Answer 3

a saturated fatty acids have no carbon to carbon double bonds and has no room left in the hydrocarbon chain where as a unsaturated fatty acid contains carbon to carbon double bonds has room for more hydrogen atoms on the hydrocarbon chain.

Question 4

how does the double bond affect the hydrocarbon chain

Answer 4

It causes a kink in the chain which can affect its properties

Question 5

what’s the physical difference between saturated and unsaturated fatty acids

Answer 5

saturated fatty acids are normally solid at room temperature where as unsaturated fatty acids are normally oils and fats

Question 6

list the functions of lipids

Answer 6

• energy storage molecules in animals and plants
  -structural component in the biological membrane - phospholipids
  -waterproofing- as they are insoluble
  -insulation - can help retain heat

Question 7

2 reasons why lipids are a good energy store

Answer 7

as they are relatively compact and are insoluble in water

Question 8

what is the general formula for a saturated fatty acid

Answer 8

RCOOH

Question 9

why is consumption of too many saturated fats considered unhealthy

Answer 9

as saturated fats can lead to increased LDL cholesterol levels which can contribute to heart disease and strokes.

Question 10

which part of the phospholipid is hydrophilic and which is hydrophobic

Answer 10

the polar head is hydrophilic and the un polar fatty acid tail is hydrophobic

Question 11

what is the bond called between a fatty acid glycerol

Answer 11

ester bond

Question 12

what is the name of the test for lipids called

Answer 12

the emulsion test

Question 13

describe the test for lipids

Answer 13

the sample being tested needs to be mixed with absolute ethanol which will dissolve any lipids present. Then shake with an equal volume of water and then if any lipids were present the dissolved ones will come out of the solution as they are insoluble in water and a cloudy white emulsion will form

Question 14

why are triglycerides insoluble in water

Answer 14

as they are non polar

Question 15

how are triglycerides formed

Answer 15

formed by condensation reactions between glycerol and 3 fatty acids and 3 molecules of water are released

Question 16

what is glycerol a type of

Answer 16

its a type of alcohol

Question 17

what type of molecules are fatty acids

Answer 17

organic molecules

Question 18

how many ester bonds are present in a triglyceride and how can they be broken

Answer 18

there are 3 ester bonds present which can be broken by hydrolysis

Question 19

describe what unsaturated fatty acids are

Answer 19

unsaturated fatty acids contain carbon to carbon double bonds, and don’t contain the maximum number of hydrogen atoms which means the hydrocarbon chain isn’t full. Unsaturated fatty acids have a kink in the due to the double bond present

Question 20

what does unsaturated fatty acids make lipids have

Answer 20

a low melting point meaning the melt more easily this is why most oils are unsaturated

Question 21

what does monounsaturated mean

Answer 21

if there is only 1 carbon to carbon double bond then the fatty acid is monounsaturated

Question 22

what does polyunsaturated mean

Answer 22

when there are 2 or more carbon to carbon double bonds then the fatty acid is polyunsaturated

Question 23

why are unsaturated fatty acids not solid

Answer 23

as due to the carbon to carbon double bond present this means the fatty acid molecules can;’t be tightly packed together so they can’t be solid

Question 24

describe what saturated fatty acids are

Answer 24

they have no carbon to carbon double bonds present is the hydrocarbon chain. The hydrocarbon chain is full. They are solid.

Question 25

what is artherosclerosis

Answer 25

when there are fatty deposits in the coronary arteries

Question 26

what is hypertension

Answer 26

high blood pressure

Question 27

what are the main causes of heart disease

Answer 27

main causes are arteriosclerosis and hypertension

Question 28

what are also contributing factors to heart disease

Answer 28

diet that is high in saturated foods, smoking, lack of exercise and aging

Question 29

what makes lipoprotein

Answer 29

when lipids and proteins combine

Question 30

where and how do lipoproteins form

Answer 30

when food has been absorbed in the small intestine lipids and proteins combine to make lipoproteins

Question 31

where do lipoproteins go

Answer 31

they travel all around the body in the blood stream

Question 32

what type of lipoproteins build up if the diet is high in saturated fats

Answer 32

Low density lipoproteins build up - LDL

Question 33

What happens when LDL builds up

Answer 33

fatty material called atheroma is deposited in the coronary artery which restricts the blood flow and oxygen delivery to the heart tissue. the restricted blood flow can result in angina or if the coronary arteries become completely blocked a heart attack can occur

Question 34

what can the restricted blood flow to the heart as a result of LDL build up result in

Answer 34

it can result in angina or if the coronary arteries become completely blocked a heart attack

Question 35

what does the body make more of when the diet has a high proportion of unsaturated fats

Answer 35

the body makes more high density lipoproteins - LDL

Question 36

What does high density lipoproteins carry

Answer 36

HDL carry harmful fats to the liver for disposal

Question 37

What does the higher ratio of HDL:LDL in a person create

Answer 37

it creates a lower risk of cardiovascular disease and coronary heart disease

Question 38

what lines the inner wall of the artery

Answer 38

smooth endothelial lining

Question 39

how many fatty acid tails does a triglyceride have compared to a phospholipid

Answer 39

a triglyceride has 3 fatty acid tails and a phospholipid has 2 fatty acid tails

Question 40

what do phospholipids contain which triglycerides don't

Answer 40

a phosphate group

Question 41

what's the difference in the polarity of triglycerides and phospholipids

Answer 41

triglycerides are non polar so are completely hydrophobic where as phospholipids have a hydrophilic head and a hydrophobic tail

Question 42

how do lipids act as an energy store in plants and animals

Answer 42

as triglycerides contain more than 1 carbon - hydrogen bonds than carbohydrate, therefore when one gram of fat is oxidised yields around twice as much energy as a carbohydrate would

Question 43

where is fat stored in animals and plants

Answer 43

in animals fat is stored under skin and around organs and in plants triglycerides are stored as oils in seeds

Question 44

how do lipids act as a thermal insulator

Answer 44

as when stored under skin it acts as a thermal insulator which reduces heat loss

Question 45

how do lipids provide protection

Answer 45

as fat is often stored around delicate organs such as the kidneys

Question 46

how do lipids provide low density and buoyancy

Answer 46

as fat has a fairly low density so it helps animals like polar bears float in water as it increase their buoyancy.

Question 47

how do lipids act as steroids and cholesterol

Answer 47

as steroids which include hormones are lipids. they have a ring structure rather than a long chain structure

Question 48

how do lipids form the cell membrane

Answer 48

as phospholipids form a bilayer which is the basis of all cell membranes and the phospholipid bilayer allows the transport of non polar molecules across the cell membrane by simple diffusion

Question 49

what can lipids dissolve in

Answer 49

in organic solvents like alcohols and propane

Question 50

summaries the functions of lipids

Answer 50

-in biological membranes -eletrcial insultion -energy reserve in both animal and plants -thermal insulation -protection -metabolic water -waterproofing

Question 51

how do lipids provide electrical insulation

Answer 51

as the myelin sheath that surrounds the acorns of nerve cells

Question 52

how do lipids provide metabolic water

Answer 52

as this water is released in chemical reaction in the body and triglycerides produce a lot of metabolic water when oxidised

Question 53

what are waxes

Answer 53

they are a type of lipid which met above 45 degrees and has a role of waterproofing

Question 54

how do lipids produce waterproofing

Answer 54

as waxes reduce water loss in the insects exoskeleton and in the cuticle of plants