6

Question 1

what caused membrane formation

Answer 1

decrease in ionic interactions with water (hydrophobic effect). H-bonding between head groups and water, and van der waal’s for the tails

Question 2

what can’t go through biological membranes

Answer 2

polar or charged molecules

Question 3

what do membrane proteins do

Answer 3

move shit across and transmit signals

Question 4

why do you need membrane fluidity

Answer 4

because you need to change protein conformation in order to signal and move stuff, therefore you need the membrane to move

Question 5

what is membrane fluidity caused by

Answer 5

noncovalent bonds breaking and forming essentially. this is in turn from the lipids (such as cholesterol) in the membrane

Question 6

fluid mosaic model proposed when and where

Answer 6

early 1970s by singer and nicolson

Question 7

what makes a membrane fluid and mosaic

Answer 7

membrane components move rapidly. diverse mixture of lipids, embedded and peripheral proteins, carbohydrates on the surface

Question 8

recent modifications to the lfuid mosaic model

Answer 8

movement of lipid and membrane proteins differ in pure lipid and biological membrane. in biological membranes there are more restrictions

Question 9

FRAP

Answer 9

label cell surface molecules (lipid or protein) with fluorescent fluorophore. use high intensity laser to bleach it in a small part, measure the mobility of other molecules into affected region. so you get a curve

Question 10

single molecule tracking fluorescence microscopy

Answer 10

antibody on a single molecule, and you see how fast it moves

Question 11

what tends to trap proteins and lipids into interacting

Answer 11

lipid rafts

Question 12

lateral diffusion of protein depends on what aside from lipid rafts

Answer 12

cytoskeleton (anchored on it) or extracellular components

Question 13

what would SDS do on a FRAP experiment

Answer 13

denature the proteins. fluorescent proteins, lipids are now all in solution, and you ahve no results

Question 14

what would a crosslinker do on a FRAP experiment

Answer 14

decrease fluidity while keeping cell intact, decreasing recovery of fluorescence (or completely remove recovery)

Question 15

which side are sugars/oligosaccharides present on a double layered membrane

Answer 15

they are added on the exterior side onto lipids and proteins. this is because it is mediated by enzymes in the ER and golgi

Question 16

why do you need sugars on lipids and proteins

Answer 16

membrane insertion and cell recognition

Question 17

what is a type of post translational modification for membrane proteins

Answer 17

adding sugars

Question 18

how fast is moving lipids from one leaflet to another, why

Answer 18

very slow. flip flop diffusion is slow because of the polar head group making it energetically unfavorable

Question 19

flippase. what does it move, what does it need

Answer 19

a membrane protein that moves PE and PS from outer to inner leaflet. needs ATP

Question 20

floppase. what does it move, what does it need

Answer 20

moves PC SM from cytosolic to outer leaflet, needs ATP

Question 21

scramblase. what does it do, what does it need

Answer 21

does not need ATP. moves stuff down the concentration gradient, so reduces assymmetry

Question 22

what are lipids. what do they do?

Answer 22

type of molecule that provides structural support for cells and organelles. stores carbons for energy, plays a role in info transduction and signalling.

Question 23

solubility properties of lipids.

Answer 23

not soluable in water, very soluable in nonpolar solvents.

Question 24

how does diversity affect lipids?

Answer 24

they can be hydrophobic or amphipathic, depending on the diverse chemical structures and functional groups.

Question 25

what are micelles made of

Answer 25

single tailed lipids. cam be inside out or normal (inside out has water inside)

Question 26

monolayer vs bilayer. when does each form

Answer 26

bilayers have water on both side, monolayer only one side

Question 27

unilammelar vescicle is also known as __. what is it

Answer 27

a liposome. it is a double layered circle thing

Question 28

fatty acid numbering from the terminal methyl uses what symbol

Answer 28

omega

Question 29

double bonds numbered from the carboxylic acid uses what symbol

Answer 29

the triangle

Question 30

free fatty acids are

Answer 30

not bound to a headbone or backbone via ester bonds. known as FFAs

Question 31

monosaturated fatty acid

Answer 31

1 double bond

Question 32

polysaturated fatty acid (pufa)

Answer 32

more than 1 double bond

Question 33

what would you call an 18 carbon chain with a double bond 9 carbons from the carboxylic acid

Answer 33

18:1 omega 9

Question 34

which fatty acids are essential

Answer 34

omega 3 and omega 6

Question 35

are omega 3 and 6 mono or polyunsaturated

Answer 35

poly

Question 36

bad vs good fats

Answer 36

saturated (TAG triacylglyceride) and unsaturated trans are bad. unsaturated and cis are good

Question 37

what decreases membrane fluidity

Answer 37

saturated fatty acids (closely packed), longer chains (van der waals)

Question 38

what does lower membrane fluidity do to melting temperature

Answer 38

higher melting temperature. melting temperature is an index of membrane fluidity

Question 39

what type of fatty acids have kinks

Answer 39

cis

Question 40

why do cis kinks increase membrane fluidity

Answer 40

decreases van der waal's by making the bottom of the fatty acid no longer interact

Question 41

how do membrane lipids melt

Answer 41

it goes from a gel-like solid phase to a liquid crystalling phase

Question 42

what is the ideal temperature for a membrane lipid

Answer 42

slightly above melting temperature so you can have conformational changes

Question 43

phase transitions for pure lipid samples and native membranes

Answer 43

pure lipid has sharp and well defined transition temperatures, native membranes have broad peaks

Question 44

tri-acyl glycerol are used for what and where

Answer 44

efficient, unlimited energy reserve of reduced carbon chains (saturated to pack more). a dehydrated storage form of lipids in adipocyte cells used to store energy

Question 45

structure of TAG

Answer 45

3 fatty acids bound to glycerol backbone through ester linkages. fatty acid tails contain double bonds creating mixed triglycerides

Question 46

2 types of amphipathic lipids

Answer 46

glycerophospholipid and sphingolipids

Question 47

most common steroid in membranes

Answer 47

cholesterol

Question 48

glycophospholipid structure

Answer 48

2 fatty acid chains, phosphate and a head group (polar). the head group can be ethanol or serine. 3 carbon backbone

Question 49

sphingolipid structure

Answer 49

a long fatty acid with a sphingosine group (amine that connects to the carbonyl carbon in the fatty acid). also has a 3 carbon backbone and a polar head group.

Question 50

examples of sphingolipid

Answer 50

sphingomyelin and ganglioside (sugar head group)

Question 51

cholesterol metabolism

Answer 51

cortisol, testosterone, bile salts

Question 52

why do you need cholesterol

Answer 52

dietary lipid absorption, moderate membrane fluidity and signal transduction.

Question 53

what does cholesterol form complexes with

Answer 53

sphingolipids, glycolipids, some lipid anchored proteins to form lipid rafts

Question 54

cholesterol effects on membrane fluidity and melting temperature

Answer 54

decreases melting temperature by disrupting noncovalent bonds. modulates membrane fluidity

Question 55

why are lipid compositions on membranes different

Answer 55

cells control synthesis of different kinds of membrane lipid and target them to certain organelles and leaflets.

Question 56

peripheral membrane proteins adhere to what

Answer 56

surface of lipid membrane OR integral membrane proteins through noncovalent interactionsh

Question 57

how to remove peripheral membrane proteins

Answer 57

increasing salt, changing pH (milder conditions)

Question 58

integral membrane proteins location

Answer 58

span membrane with TMs

Question 59

removing integral membrane proteins

Answer 59

harsh conditions (detergents that swap places with proteins to solublize or organic solvents)

Question 60

will detergents remove peripheral proteins

Answer 60

yes of course

Question 61

lipid anchored proteins removal

Answer 61

harsh detergents or solvents

Question 62

issues with harsh detergents and solvents

Answer 62

may break protein structure

Question 63

how are lipid anchored proteins kept in place

Answer 63

lipid chains covalently attached to amino acid functional groups and side chains

Question 64

what is the fatty acid present and what atom is the fatty acid linked to for S-palmitoylation

Answer 64

palmito group is the fatty acid, linked to sulfur (cysteine bond)

Question 65

where are GPI anchored proteins

Answer 65

outside of the cell because they are linked in the ER

Question 66

how are GPI proteins kept in place

Answer 66

covalently linked through a sugar chain to a lipid anchor

Question 67

what do you do after you get a mixture of integral and peripheral proteins

Answer 67

chromatography to separate the 2

Question 68

how do detergents solublize membrane proteins

Answer 68

by creating miscelles around hydrophobic regions

Question 69

physical properties of detergents

Answer 69

amphipathic molecules

Question 70

CMC critical micelle concentration

Answer 70

how much is needed for detergent to spontaneously form stable micelle structure

Question 71

why do you want to be above the CMC to solublize proteins

Answer 71

because then micelles can form

Question 72

methods to deduce primary sequence

Answer 72

DNA sequencing, protein prediction algorithms

Question 73

how many AAs for alpha helix TM

Answer 73

20

Question 74

how wide is the membrane in angstroms

Answer 74

30

Question 75

how wide is an amino acid in angstroms

Answer 75

1.5

Question 76

how is the hydropathy index determined

Answer 76

average ktye-doolittle hydrophobicity values within a segment. move window one residue and redo. plot on central amino acid

Question 77

what does window size do for hydropathy plot

Answer 77

smaller window is noisier, larger is smoother

Question 78

how many amino acids must you average for the hydropathy plots

Answer 78

odd numbers so you can attribute to center AA

Question 79

requirements for finding a TM in hydrophobic plot

Answer 79

above 0 (means hydrophobic), 20 AA wide and 1-1.5 tall.

Question 80

do hydrophobic plots predict or confirm structure

Answer 80

predict