lipids 1

Question 1

describe lipids?

Answer 1

they are all insoluble in water and soluble in organic solvents

Question 2

what are the functions of lipids?

Answer 2

structural components of membranes
energy reserves, mainly in the form of triacylglycerols
lipids and lipid derivatives serve as vitamins and hormones

Question 3

what are the 7 types of lipids?

Answer 3

fatty acids
fats and oils (triacylglycerols)
phospholipids
glycolipids
prostaglandins
terpenes (a.k.a isoprenoids)
steroids

Question 4

why are fatty acids important?

Answer 4

they are essential components of other lipids

Question 5

describe fatty acids?

Answer 5

contain a long hydrocarbon chain (non-polar end) and a terminal carboxylic acid group (polar end)

Question 6

numbering of the carbon in an fatty acids starts where?

Answer 6

carboxylic acid group end

Question 7

at physiological pH the fatty acid is what?

Answer 7

the carboxyl groups of fatty acids are readily ionized
this makes fatty acids negatively charged (COO-)

Question 8

how many carbons do most fatty acids contain?

Answer 8

12 to 20 carbon atoms

Question 9

what is a saturated fatty acid?

Answer 9

contain no carbon-carbon double bonds

Question 10

12:0 what does the 12 represent?

Answer 10

12 carbons and 0 double bonds

Question 11

name another saturated fatty acid?

Answer 11

palmitic acid

Question 12

what is an unsaturated fatty acid?

Answer 12

contain at least one carbon-carbon double bond

Question 13

what us a monosaturated fatty acid?

Answer 13

fatty acids have 1 C=C bond,

Question 14

what is a polyunsaturated fatty acid?

Answer 14

fatty acids have 2 or more C=C bonds

Question 15

where are cis double bonds found?

Answer 15

unsaturated fatty acids

Question 16

how are most fatty acids made?

Answer 16

precursor molecules in the body (non-essential fatty acids)

Question 17

what are the 2 essetnail fatty acids?

Answer 17

linoleic acid
linolenic acid

Question 18

can linolenic acid and and linolec be synthesized from precursors?

Answer 18

no

Question 19

what can linoleic and linolenic aicds be found?

Answer 19

obtained in the diet found in fish, shellfish,etc

Question 20

what are omega 3 fatty acids?

Answer 20

unsaturated fatty acids in which the double bond closest to the methyl (omega) carbon occurs at the third carbon in from that end

Question 21

what can omega 3 inhibit?

Answer 21

platelet aggregation
increase the ratio of high-density to low-density lipoproteins while lowering overall plasma lipid levels
they may inhibit some cancers

Question 22

what is shortest omega 3 fatty acid called?

Answer 22

linolenic

Question 23

what are omega 6 fatty acids?

Answer 23

unsaturated fatty acids in which the double bond closest to the methyl (omega) carbon occurs at the sixth carbon in from that end

Question 24

diets in which the ratio of omega 6 to omega 3 fatty acids is high has linked to what>

Answer 24

been linked to promotion of some cancers

Question 25

what is the shortest omega 6 fatty acid?

Answer 25

linoleic

Question 26

what does the chain length affect>

Answer 26

affects the melting point of fatty acids the longer the fatty acid, the higher the melting point shorter fatty acids are more fluid than longer ones

Question 27

how does saturatio effect a fatty acid?

Answer 27

affects the melting point more saturated the fatty acid, the higher the melting point an unsaturated fatty acid is more fluid than a saturated one of similar size

Question 28

longer chains that are more saturated are what?

Answer 28

likely to be solid at room temperature they can pack more closely together to form a solid structure than shorter or unsaturated chains

Question 29

why are fats and oils essential?

Answer 29

fats carry essential vitamins = A D E and K provide our most concentrated form of dietary energy

Question 30

why are fats and oil important?

Answer 30

They are the precursors from which we synthesize our own fat They are the precursors from which we synthesize our own fat

Question 31

how is fat stored?

Answer 31

adipose tissue

Question 32

what is adipose tissue made from?

Answer 32

made up of specialised cells called adipocytes, which contain globules of stored lipid

Question 33

how are triacylglycerols formed?

Answer 33

3 fatty acids + 1 molecule of glycerol link together to form 1 triacylglycerol molecule + 3 water molecules

Question 34

fats are

Answer 34

TAGs that are solid at RT

Question 35

oils are

Answer 35

TAGs that are liquid at RT

Question 36

TAGs found in animals tend to contain?

Answer 36

saturatedhydrocarbon chains (animal fats - like lard, butter)

Question 37

TAGs found in plants tend to contain

Answer 37

unsaturatedhydrocarbon chains (oils - like olive oil, palm oil)

Question 38

how can lipids be transported around the body?

Answer 38

as fatty acids, but are stored in adipocytes as TAGs

Question 39

how can TAGS be hydrogenated?

Answer 39

if they contain unsaturated fatty acids

Question 40

can tags be broken down to their glycerol and fatty acid components

Answer 40

boil with acid or alkali - superheated steam - lipases

Question 41

what is RANCIDITY

Answer 41

development of undesirable odors and flavors in fats and oils when they undergo oxidation.

Question 42

what is a soap?

Answer 42

soap is the combination of a fatty acid with a metal

Question 43

what is the most commaest soaps?

Answer 43

sodium or potassium salts of fatty acids

Question 44

how are soaps made?

Answer 44

made by the hydrolysis (saponification) of oils or fats

Question 45

what are the steps to produce soap?

Answer 45

heat oil or fat with dilute NaOH when hydrolysis is complete, get rid of excess glycerol and alkali by boiling with large amounts of water precipitate soap by the addition of NaCl dry, add perfume, colour, etc

Question 46

how do soaps work?

Answer 46

soaps are amphiphilic molecules they have an ionic polar end (hydrophilic) and a non-polar hydrocarbon chain (lipophilic because grime and dirt are often hydrophobic, they associate with the lipophilic ends of the soap molecules

Question 47

how do soap molecules arrange themselves when faced with dirt>

Answer 47

molecules arrange themselves into micelles & dirt is incorporated into the interior of these micelles

Question 48

what happens when the miccles are immersed in the dirt?

Answer 48

this means it is emulsified (solubilised) in aqueous solution) and thus can becleaned away