lipids

Question 1

do lipids have shared characteristics

Answer 1

gernally no, they are very diverse and are mainly classified by their hydrophobic nature

Question 2

what are the functions of lipids

Answer 2

1.) energy storage

2.) insulation from environment

3.) water-repellent

4.) buoyancy control and acoustics in marine animals

5.) Cofactors for enzymes

6.) signaling molecules

7.) pigments

8.) antioxidants

Question 3

how is energy stored in lipids

Answer 3

as fats or fatty acids, which are a derivative of hydrocarbons which can be oxidized to CO2

Question 4

what is the stucture of fatty acids

Answer 4

long hydrocarbon tails (4-36 carbons long) with a carboxylic acid head

Question 5

how many carbons and double bonds in stearic acid

Answer 5

18 carbons, no double bonds

Question 6

how many carbons and double bonds in oleic acid

Answer 6

18 carbons, one double bond

Question 7

how many carbons and double bonds in linoleic acid

Answer 7

18 carbons, two double bond

Question 8

how many carbons and double bonds in alpha linoleic acid

Answer 8

18 carbons, three double bonds

Question 9

what are fatty acids classified as

Answer 9

the simplest lipids

Question 10

which fatty acid is fullys aturated and which is unsaturated

Answer 10

stearate ion is saturated with no double bonds

oleate ion is unsaturated with one double bond

Question 11

the number of carbon atoms in fatty acids is usually:

Answer 11

even numbered betwen 12 and 24

Question 12

in monounsat. FA, where is the double bond?

Answer 12

between C9 and C10

Question 13

in poly unsat FA, where is the double bonds?

Answer 13

between C12 and C15

Question 14

in poly unsat FA, how are double bonds separated

Answer 14

by a methylene group

Question 15

what conformation are double bonds in for fatty acids generally?

Answer 15

cis configuration

Question 16

how does solubility of lipids change as the length of the hydrocarbon tail grows?

Answer 16

solubility decreases because it becomes more hydrophobic

Question 17

how does the melting point of a fatty acid change as the length of the hydrocarbon tail grows?

Answer 17

the melting point increases because the van der waals interactions increase between molecules as the tail grows more surface area

Question 18

how does the melting point of a fatty acid change when a double bond is introduced?

Answer 18

it decreases

Question 19

why does the melting point of a fatty acid change with the introduction of a double bond

Answer 19

A cis double bond introduces a kink, disrupting packing and sharply lowering the melting point (why oils are liquid at room temperature).

Question 20

what are the rules for nomenclature of a fatty acid

Answer 20

the numbering begins at the carbonyl carbon

• the length of the chan (# of carbons) and the # of double bonds is separated by a colon (18:1)
• The position of the double bond is indicated by a ∆# where the # is the carbon where the double bond starts

Question 21

what does the name 18:1 (∆9) cis-9-octadecenoic acid tell you?

Answer 21

it tells you there are 18 carbons with a double bond starting at C9 in the cis conformation

Question 22

what is the difference between a omega 3 fatty acid and an omega 6 fatty acid?

Answer 22

RELATIVE to the FURTHEST carbon (the OMEGA), a double bond is formed between C3 and C4 for omega 3

for omega 6, this double bond is fored between C6 and C7 relative to the omega carbon

Question 23

why are saturated fatty acids more waxy than unsaturated fatty acids?

Answer 23

saturated fatty acids do not have double bonds so they can pack together more closley

double bonds are kinked and unable to form solids

Question 24

why do fatty acids aggregate together

Answer 24

the hydrophobic affect

Question 25

how are fatty acids used in the body

Answer 25

to make fats

Question 26

what is the primary role of fats

Answer 26

to store energy

Question 27

why are seeds oily?

Answer 27

plants need to store a lot of energy in seeds so that they can grow into a full plant, they store energy in the form of triaglycerols

Question 28

what are triacylglycerols? what are they composed of?

Answer 28

they are the simplest forms of lipids and are composed of three fatty acids that are bonded through ester bonds to a glycerol molecule

Question 29

what is the physical characteristic of triacylgylcerols

Answer 29

they are non polar and hydrophobic

Question 30

what are the three primary functions of fats

Answer 30

- they store long term energy due to their highly reduced state - they are lighter and more compact since they are not associated with as many water molecules as sugars - they are good thermal insulators since they have high heat capacities

Question 31

why are fats better at storing energy than glucose or glycogen?

Answer 31

they are more highly reduced, meaning the carbon atoms are electron rich and release more energy as compared to oxidized sugar molecules

Question 32

what are fats more highly reduced than sugars?

Answer 32

fats are more composed of C-H bonds, which are not polarized, meaning the carbon is not oxidized and is more electron rich than an oxidized C-O bond. in sugars, the molecules are comprised of hydrocarbons, which make them more highly oxidized and the carbons are electron deficient and release less energy when broken down

Question 33

to derive more energy from a molecule, do you want a more highly oxidized or reduced carbon?

Answer 33

you want a more highly reduced carbon since the carbon is not electron deficient

Question 34

why is it important that there are less water molecules associated with lipids?

Answer 34

this makes them more compact, meaning you can store more of them per unit of volume in your body

Question 35

if you need quick acting energy, what source of energy will you pull from? why?

Answer 35

glucose and glycogen are more freely accessible and can be broken down more rapidly, whereas lipids are sequestered away in organelles of cells, making them harder to break down and are better for long term energy storage

Question 36

why do bears accumulate fat for hiberation?

Answer 36

- fats are good insulators - fats store more long lasting, slow releasing energy - more fat molecules can be stored per unit of volume

Question 37

whyis it bad to ingest a lot of saturated fats?

Answer 37

the fats you ingest are ultimately incorporated into your bloodstream and eventually your cellular membranes. Saturated fats are more rigid and can pack more tightly. Meanwhile, unsaturated fats cannot be packed as tightly due to their double bonds, making them more liquidy. When saturated fats are incorporated into the cell membrane, the resulting membrane is very rigid which can lead to issues in circulation