Membrane Structure and Function

Question 1

outer leaflet

Answer 1

exposed to the external side

Question 2

inner leaflet

Answer 2

exposed to the cytoplasmic side

Question 3

leaflets can vary between

Answer 3

different parts of the membrane

phospholipid content, protein content, etc

Question 4

the phospholipid bilayer undergoes

Answer 4

natural oscillation

Question 5

glycerol backbone contains

Answer 5

3 OH groups

Question 6

the 3 OH groups of glycerol are sites for

Answer 6

side chain attachment

Question 7

the glycerol backbone is attached to

Answer 7

fatty acid tails

polar phosphate head

Question 8

sphingosine backbone is usually O-linked to a

Answer 8

charged group and amide-linked to an acyl group, such as a fatty acid

Question 9

when you have a FA attached to the glycerol=

Answer 9

nonpolar

Question 10

when you have a phosphate attached to the glycerol=

Answer 10

polar

Question 11

diffusion in saturated lipids

Answer 11

slow because it is tightly packed

Question 12

diffusion in mixed saturated and unsaturated lipids

Answer 12

quick because there is spacing created because of the kinks and is therefore much more open and molecules can move quicker

Question 13

membrane phospholipid bilayers serve as

Answer 13

semipermeable membranes

Question 14

charged molecules cannot diffuse through

Answer 14

the lipid bilayer

Question 15

O2, N2, H2O, and CO2 can

Answer 15

diffuse rapidly across the lipid bilayer

Question 16

glycine and other amino acids cannot

Answer 16

diffuse across membranes

Question 17

hydrophobic compounds can

Answer 17

diffuse across membranes

ex. estrogen

Question 18

lipid contents of the plasma membrane are distributed

Answer 18

asymmetrically

Question 19

lipid components found outside of the cell (3)

Answer 19

sphingomyelin
glycolipid
phosphatidylcholine

Question 20

lipid components found ion the cytoplasmic leaflet (3)

Answer 20

phosphatidylserine
phosphotidylinositol
phosphatidylethanolamine

Question 21

cholesterol distribution

Answer 21

symmetrically distributed amongst the outer and inner leaflet

Question 22

phospholipids can be cleaved into products that function as important

Answer 22

intracellular second messangers

Question 23

PIP2 is cleaved by phospholipase C to form

Answer 23

IP3
DAG
important in intracellular signaling

Question 24

when phospholipids are dispersed in water, they naturally for

Answer 24

vesicles

multilammellar or monolayer/unilammellar

Question 25

what happens when water and oil are mixed rapidly?

Answer 25

it is initially cloudy because vesicles are forming. eventually they will settle and separate

Question 26

liposomes are

Answer 26

artificially prepared vesicles composed of a lipid bilayer

Question 27

liposomes can be used to

Answer 27

administer and transport nutrients and pharmaceutical drugs in the body

Question 28

homing peptides

Answer 28

can target molecules on the outside

Question 29

liposomes have a protective layer against

Answer 29

``` immune destruction (prevents immune interaction and destruction) ```

Question 30

liposomes contain a (6)

Answer 30

- protective layer against immune destruction - DNA - homing peptide - drug crystalized in aqueous fluid - lipid-soluble drug in bilayer - lipid bilayer

Question 31

pfizer and moderna mechanism of action

Answer 31

liposome contains RNA that codes the spike protein. spike protein will attach to the virus, produce spike protein, and the body will create an immune response to destroy the virus

Question 32

bottom line of liposome mechanisms

Answer 32

many drugs use liposome technology to treat diseases

Question 33

the alpha helix is a common structural feature of

Answer 33

transmembrane regions of integral membrane proteins

Question 34

amino acids that make up the alpha helix are

Answer 34

uncharged to interact with the inner leaflet

Question 35

membrane protein functions (4)

Answer 35

cell-cell contact/adhesion receptor signaling systems pores and channels (transport) enzymes

Question 36

absorption and synthesis of cholesterol is important and much is known about

Answer 36

hereditary problems

Question 37

other components of the plasma membrane (2)

Answer 37

cholesterol | triglycerides

Question 38

FRAP shows us that

Answer 38

proteins move within the plasma membrane

Question 39

FRAP

Answer 39

protein is labeled with fluorescent dye, shine a laser beam on the plasma membrane, fluorescence is lost, but overtime, this area regains fluorescence because proteins move within this region that the laser bleached

Question 40

flippase

Answer 40

ex. PS, PE | from the outer to the inner leaflet

Question 41

floppase

Answer 41

ex. PC, SL | from the inner to the outer leaflet

Question 42

flippase and floppase require

Answer 42

ATP because they move against a concentration gradient

Question 43

scramblase

Answer 43

ex. cholesterol transfers between the inner and outer leaflet does not require ATP

Question 44

scramblase mechanism

Answer 44

lipid bilayer of the ER phospholipid synthesis adds to the cytosolic half of the bilayer scramblase catalyzes flipping of phospholipid molecules symmetric growth of both halves of the bilayer

Question 45

flippase mechanism

Answer 45

asymmetric lipid bilayer of the plasma membrane delivery of new membrane by exocytosis flippase catalyzes flipping of specific phospholipids to cytoplasmic monolayer

Question 46

lipid rafts are specialized domains predominately within plasma membranes of cells which

Answer 46

organize membrane proteins and glycolipids in groupings, having functional implications in terms of receptor trafficking, neurotransmission, and membrane fluidity

Question 47

lipid rafts move as

Answer 47

unit instead of individual parts

Question 48

lipid rafts differ from the plasma membrane as a whole by being enriched in

Answer 48

cholesterol and sphingolipids

Question 49

lipid rafts tend to be resistant to

Answer 49

dissociation by detergents which can freely dissociate the fluid membrane sections

Question 50

caveolae

Answer 50

invaginations of the plasma membrane

Question 51

caveolae form from

Answer 51

lipid rafts

Question 52

it has been proposed that lipid rafts play a role in cell signaling events for the (3)

Answer 52

b-cell antigen receptor t-cell antigen receptor IgE receptor

Question 53

ultracentrifugation

Answer 53

used to separate different membrane bound compartments like mitochondria and nucleus

Question 54

density gradient ultracentrifugation

Answer 54

used to separate biological membranes containing lipids (and having lower densities) from proteins (having higher densities)

Question 55

electron microscopy

Answer 55

An EM has greater resolving power than a light microscope and can reveal the structure of smaller objects because electrons have wavelengths about 100,000 times shorter than visible light photons. They can achieve better than 50 pm resolution and magnifications of up to about 10,000,000x whereas ordinary, non-confocal light microscopes are limited by diffraction to about 200 nm resolution and useful magnifications below 2000x.

Question 56

fluorescence microscopy

Answer 56

uses fluorescence and phosphorescence instead of, or in addition to, reflection and absorption to study properties of organic or inorganic substances

Question 57

atomic force microscopy

Answer 57

very high-resolution type of scanning probe microscopy, with demonstrated resolution on the order of fractions of a nanometer, more than 1000x better than the optical diffraction limit

Question 58

cell fractionation mechanism

Answer 58

due to centifugational force, large or verse dense particles move toward the bottom of a tube and form a pellet cell structures can be separated into various fractions by spinning the suspension at increasing revolutions per minute. membranes and organelles from the resuspended pellets can then be further purified by density gradient centrifugation

Question 59

detergents solubilize

Answer 59

membranes

Question 60

detergent mechanism

Answer 60

detergent positions itself within the membrane so the membrane falls apart. it encapsulates the lipids so they cannot come back together

Question 61

freeze faction is used to

Answer 61

split apart the membrane

Question 62

cantilever deflection can trace

Answer 62

the topography, where proteins are located, etc

Question 63

virus fusion to the plasma membrane

Answer 63

enveloped virus attaches to the cell membrane of recipient cell via receptors, and receptors on the surface of the virus, followed by fusion where the envelope blends with the cell membrane and releases its contents (genome) into the cell

Question 64

enveloped viruses containing human pathogens

Answer 64

``` DNA viruses (ex. herpes) RNA viruses (ex. corona) retroviruses (ex. HIV) ```

Question 65

coronavirus

Answer 65

spike protein binds to receptor on a mammalian cell to trigger fusion

Question 66

ACE2 concentrates on the

Answer 66

airway epithelium cells

Question 67

why does washing hands with soapy water work to reduce/ prevent infection?

Answer 67

using detergent to break down a membrane so viruses cannot bind to the membrane and fuse