lipids

Question 1

what are the 6 classes of lipids ?

Answer 1

fatty acids
triacylglycerols
phospholipids
steroids
sphingolipids
waxes

Question 2

what are the features of fatty acids

Answer 2

hydrocarbon chain
insoluble in water
highly soluble in organic substances

Question 3

what are fatty acids called?

Answer 3

monocarboxylic acids

Question 4

saturated fatty acids

Answer 4

c-c single bonds
maximum number of hydrogen atoms possible

Question 5

example of a saturated fatty acid

Answer 5

palmitate 16:0
16C no double bond

Question 6

unsaturated fatty acids

Answer 6

have one or more double bonds

Question 7

example of a monosaturated fatty acid

Answer 7

oleic acid
18:1delta9
one double double bond on carbon 9&10

Question 8

what causes a kink in the chain ?

Answer 8

a double bond

Question 9

polyunsaturated

Answer 9

two or more double bonds

Question 10

what makes a higher melting point ?

Answer 10

longer chain

Question 11

what does the kink prevent

Answer 11

close packing of unsaturated fatty acids

Question 12

do fatty acids occur as independent free molecules ?

Answer 12

yes but only in trace amounts

Question 13

triacylglycerols

Answer 13

simplest lipids constructed from fatty acids
3 FA linked to a single glycerol molecule

Question 14

what is glycerol

Answer 14

a three carbon alcohol with a hydroxyl group attached to each carbon

Question 15

what are simple triacylglycerols

Answer 15

same FA in all 3 chains

Question 16

what are mixed triacylglycerols

Answer 16

2 or more different FA
can be of different chain length
can be a mix of saturated and unsaturated
most -natural

Question 17

what reacts with the OH group of glycerol to from triacylglycerols

Answer 17

the carboxyl group of each FA

Question 18

what are triacylglycerols referred to as fats like?

Answer 18

solid at room temp
large proportion of saturated FA

Question 19

are most animal fats unsaturated

Answer 19

no they are mostly saturated

Question 20

what do the properties of the triacylglycerol depend on ?

Answer 20

the FA side chain

Question 21

what are triacylglycerol referred to as oils like?

Answer 21

liquid at room temp
large proportion of unsaturated FA

Question 22

what are plant fats and fish fats usually ?

Answer 22

unsaturated

Question 23

what do fat in animals do ?

Answer 23

energy reserves - store fat in adipose cells
provide insulation against low temp

Question 24

whats a phospholipid

Answer 24

two fatty acids, a phosphate group and an alcohol are attached to a glycerol

Question 25

what forms a hydrophilic head in phospholipids

Answer 25

glycerol, phosphate and alcohol

Question 26

what are the fatty acid tails in phospholipids?

Answer 26

hydrophobic

Question 27

what are amphipathic molecules

Answer 27

contain both polar and non-polar groups

Question 28

what is the structure of a phospholipid

Answer 28

2 FA chains are attached to the 1st and 2nd C of glycerol (hydrophobic tail) an alcohol (highly polar) is attached to the 3rd C of gylcerol

Question 29

what are steroids characterised by ?

Answer 29

a carbon skeleton consisting of four fused rings

Question 30

what is an important steroid

Answer 30

cholesterol

Question 31

what is cholesterol a component of ?

Answer 31

plasma membranes

Question 32

what does high levels of cholesterol in the blood lead to in animals ?

Answer 32

cardiovascular disease

Question 33

are membrane lipids amphipathic

Answer 33

yes this is essential for membrane formation

Question 34

what do phospholipids do when they are added to water ?

Answer 34

they self-assemble into a bilayer, with the hydrophobic tails pointing towards the interior

Question 35

what is the most abundant lipid in the plasma membrane ?

Answer 35

phospholipids

Question 36

what is the composition of the average membrane

Answer 36

50-60% protein 40-50% lipid 0-5% carbohydrate

Question 37

what are membrane proteins classified as ?

Answer 37

peripheral proteins integral proteins

Question 38

peripheral proteins

Answer 38

are bound to the surface of the membrane penetrate the hydrophobic core

Question 39

what gives each organelle its distinctive function?

Answer 39

differences in membrane proteins

Question 40

is a membrane rigid ?

Answer 40

no its fluid

Question 41

integral proteins

Answer 41

penetrate the hydrophobic core span the membrane and are called transmembrane proteins

Question 42

what do the hydrophobic regions of an integral protein consist of ?`

Answer 42

one or more stretches of non-polar amino acids, often coiled into alpha helices

Question 43

what is fluidity of a cell membrane

Answer 43

the ease with which its lipid molecules move within the bilayer

Question 44

what is fluidity determined by ?

Answer 44

chain length -shorter increases % of unsaturated FA- more increases

Question 45

can lipids move within the bilayer

Answer 45

yes

Question 46

lateral diffusion

Answer 46

within each monolayer rapid 10^7 times per day

Question 47

transverse diffusion -"flip-flop"

Answer 47

diffusion from one face of bilayer to another very slow rare- once per month

Question 48

what family of proteins facilitate flip flop movement

Answer 48

flippases

Question 49

do membrane proteins flip flop across a membrane

Answer 49

never

Question 50

self sealing property of lipids

Answer 50

break exposing hydrophobic hydrocarbon chains to water unfavourable disruption form hydrophilic edges membrane edges draw edges close fuse and reform bilayer

Question 51

what is the plasma membrane permeable to ?

Answer 51

to hydrophobic molecules can dissolve in the lipid bilayer and pass through the membrane rapidly

Question 52

what is the membrane impermeable to?

Answer 52

highly impermeable to ions and most polar molecules

Question 53

what is passive transport

Answer 53

is diffusion of a substance across a membrane from an area of high concentration to an area of low with no energy investment

Question 54

what do transport proteins do?

Answer 54

allow passage of hydrophillic substances across the membrane

Question 55

two types of transport proteins?

Answer 55

channel proteins carrier proteins both shield hydrophilic molecule from hydrophobic core

Question 56

channel proteins

Answer 56

have a hydrophilic channel that certain molecules or ions can use as a tunnel

Question 57

aquaporins

Answer 57

channel proteins that facilitate the passage of water

Question 58

carrier proteins

Answer 58

bind to molecules and change shape to shuttle them across the membrane

Question 59

facilitated diffusion

Answer 59

transport proteins speed up the passive movement of molecules across the plasma membrane

Question 60

is facilitated diffusion still passive ?

Answer 60

yes because the solute moves down its concentration gradient

Question 61

what is ATP composed of ?

Answer 61

ribose adenine and three phosphate groups

Question 62

when is energy released from ATP

Answer 62

when the terminal phosphate bond is broken

Question 63

active transport

Answer 63

requires energy, ATP performed by specific proteins embedded in the membranes

Question 64

what does active transport allow the cell to do?

Answer 64

maintain concentration gradients that differ from their surroundings

Question 65

example of one type of active transport

Answer 65

the sodium potassium pump

Question 66

what causes cystic fibrosis

Answer 66

mutated transporter

Question 67

what is CF due to

Answer 67

the loss of CL^- channel function

Question 68

what is the result of cystic fibrosis

Answer 68

abnormal high concentration of extracellular chloride- causes thickening of mucus- affects lungs, pancreas, digestive tract. salty skin