Phsl

Front 1

What does valium do?

Back 1

it is a muscle relaxant that inhibits GABA controlled ion channels in the brain

Front 2

what does PCP do?

Back 2

inhibits NMDA (glutamate) channels in the brain

Front 3

What does digoxin inhibit?

Back 3

sodium/potassium pump

Front 4

how is the phospholipid bilayer formed?

Back 4

naturally through physical properties

Front 5

what are 3 types of integral proteins?

Back 5

single pass, multiple pass, and several subunits

Front 6

what do glycolipids do to the membrane?

Back 6

give membrane fixed negative charge

Front 7

what are 2 ways a peripheral protein can link to the phospholipid

Back 7

oligosaccharides and lipid anchors (fatty acid or prenyl group)

Front 8

How is the cell volume controlled?

Back 8

total number of impermeable ions - creates osmotic force bringing water

Front 9

what determines the direction of transport in primary transporters?

Back 9

direction of transport determined by transporter

Front 10

what determines the direction of transport in secondary transporters?

Back 10

electrochemical gradient of driving ion or molecule

Front 11

which type of transporters use ATP?

Back 11

primary transporters

Front 12

methyl and acetyl groups do what to molecules?

Back 12

make them more lipid soluble

Front 13

when is diffusion an adequate method for moving molecules or ions?

Back 13

good to move short distances such as just across the membrane, not good for long distances b/c it would take way too long

Front 14

what is diffusion?

Back 14

net movement from higher to lower concentration and/or electrical gradient

Front 15

what is osmosis?

Back 15

net movement toward the higher concentration of impermeable molecules or ions; not due to charges or attraction

Front 16

what is donnan distribution?

Back 16

net movement or distribution of charged permeable ions depends on the charges on the impermeable ions

Front 17

when is a molecule or ion removed from a diffusion or osmotic gradient?

Back 17

when it is phosphorylated

Front 18

is charge, attraction or mass important in the processes of diffusion and/or osmosis?

Back 18

only mass is - slows particles, diffusion, and osmosis down

Front 19

what is paracellular diffusion?

Back 19

when water can diffuse between cells b/c there are leaky cell junctions

Front 20

do all cells have aquaporins in their plasma membranes?

Back 20

yes, but sometimes only on one side of the cell

Front 21

do you think osmoreceptor cells in the hypothalamus have aquaporins?

Back 21

yes, tell the body what the osmolarity is

Front 22

red blood cells swell when placed in a hypotonic solution. why don't frog eggs (single cells) swell when the mother lays them in hypotonic pond water?

Back 22

no aquaporins

Front 23

besides water, aquaporins also are responsible for the transport of what?

Back 23

CO2 through cell membranes in lungs

Front 24

how do hydrogen bonds influence a molecules permeability through the membrane?

Back 24

the more H bonds the less permeable the molecule is b/c it reacts more w/ water

Front 25

__________ molecules dissolve in the phospholipid bilayer and pass through the membrane

Back 25

lipid soluble

Front 26

how does pH affect the lipid solubility of weak acids and weak bases?

Back 26

Decreasing the pH increases the lipid solubility and membrane permeability of weak acids and decreases it for weak bases. Increasing the pH increases the the lipid solubility and membrane permeability of weak bases and decreases it for weak acids.

Front 27

Examples of lipid soluble substances

Back 27

1. nicotine
2. ethanol
3. heroin (diacetylmorphine) - more soluble then morphine b/c 2 acetyl groups
4. steroid hormones
4. thyroid hormones
5. many pesticides

Front 28

how does cholesterol affect membrane permeability?

Back 28

it is a neutral lipid that helps to hold the membrane together and make it tighter; makes it less permeable to water soluble substances

Front 29

how does FA chain length affect membrane permeability?

Back 29

long chain FAs pull together tighter and make the membrane more impermeable

Front 30

how do double bonds affect membrane permeability?

Back 30

they increase permeability b/c they put kinks in the membrane

Front 31

the amount of hydration depends on the ions what?

Back 31

charged density

Front 32

membrane phospholipids need to be in what state to be functional?

Back 32

liquid state - more double bonds and short FA chains to be in liquid state

Front 33

can ionized molecules pass through the membrane?

Back 33

no

Front 34

ion channel selectivity is based on what 3 things?

Back 34

1. size
2. charge
3. competition between the attraction of the pore wall and water for the ion - if there is a greater attraction to water than to the pore the ion won't move through the pore very easily; if pore attraction for the ion is about the same as the water attraction for the ion than the ion can slip into pore easily

Front 35

what are ion channels?

Back 35

-protein structures spanning the membrane that have a water filled pore
-made from several subunits, each containing several alpha helices
-most are gated
-passive movement through membrane

Front 36

describe the anatomy of an ion channel subunit

Back 36

each subunit is formed by an AA chain; most often the parts of the chain spanning the membrane are in the form of alpha helices b/c they are lipid soluble

Front 37

describe the ion selection area of an ion channel

Back 37

polar AAs line the channel w/ either + or - charges

Front 38

1.voltage gated ion channels have how many subunits?
2. ligand gated ion channels have how many subunits?
3. gap junctions have how many subunits?
4. nuclear pores have how many subunits?

Back 38

1. 4
2. 5
3. 6
4. 8

Front 39

which type of membrane transport has the fastest rate?

Back 39

ion channels are the most rapid b/c ions don't have to find a binding site in the channel; passive and active transporters are slower b/c everything that passes through has to bind to binding site and cause conformational change

Front 40

what are 4 types of ion channel controls?

Back 40

1. ligand controlled
- hormones
- transmitters
- drugs
2. voltage controlled
- changes in membrane potential
3. stretch controlled
- forces applied to the cell
4. 2nd messenger controlled
- phosphorylation
- G-proteins
- calcium ions

Front 41

what kind of channels are important in creating action potentials on nerve cells?

Back 41

voltage gated sodium and potassium channels

Front 42

1. how is resting membrane potential produced?
2. If sodium was leaking, which way would it be leaking?

Back 42

1. mostly produced by leak channels for potassium (producing positive change on the outside of the cells and a neg. charge on the inside)
2. to the inside - producing neg. charge outside cell and pos. inside

Front 43

how do voltage controlled Na+ channels open and close?

Back 43

alpha helices w/ 6 pos. charges open these channels as the resting membrane potential reaches threshold, remain open for a short time and then close (there is a pos. charge in 1 alpha helix in each subunit. the alpha helix comes down closing the channel w/ an increased potential difference across the membrane and it goes up opening the channel w/ a decreased potential difference)

Front 44

what 2 voltage controlled gating mechanisms control voltage gated Na+ channels?

Back 44

1. activation gate
2. inactivation gate
at resting membrane potential the activation gate is closed and the inactivation gate is open. at threshold the activation gate opens and Na+ enters the cell. the inactivation gate remains open for a short time and then closes so Na+ can no longer enter the cell. the activation gate remains open until the membrane potential returns to RMP through K+ channels. once the activation gate closes, the inactivation gate opens

Front 45

stretch controlled channels are important in measuring what?

Back 45

forces applied to various parts of the body:
- touch and pressure reception
- sheering forces of blood on blood vessels
- detecting motion by the vestibular system
- measuring pressure applied to bone

Front 46

what causes a stretch controlled ion channel to open?

Back 46

physical force applied to the cell

Front 47

the firing rate of the heart is proportional to what?

Back 47

stretch and pulse pressure

Front 48

w/ increased blood pressure does the heart pump harder or slow down?

Back 48

w/ increased blood pressure the heart slows down, w/ decreased blood pressure the heart pumps harder

Front 49

increased blood pressure stretches the nerve endings resulting in what?

Back 49

the opening of nonselective cation channels. cations (Na+ and Ca++) enter the nerve cells causing a decrease in membrane potential proportional to the amount of stretch. this produces action potential which travel to the medulla.

Front 50

how are the number of transport proteins in the membranes of a cell controlled?

Back 50

primarily through 2nd messenger cascades regulating gene activity

Front 51

how is a gap junction controlled? what can close the channel of a gap junction?

Back 51

2nd messenger cascades; binding of Ca++ and phosphorylation

Front 52

what do gap junctions allow?

Back 52

allow molecules and ions to directly pass from one cell into an adjacent cell. allows cells to work together and not have to work independently. Brain cells don't have gap junctions

Front 53

how does a bacterial channel transport NH3?

Back 53

NH4 ions enter the outer portion of the channel and become stabilized. Then only NH3 molecules pass through the hydrophobic portion

Front 54

passive transporters transport what type of molecules?

Back 54

molecules that would be difficult to selectively transport using channels. molecules like glucose and AAs

Front 55

T or F passive transporters exhibit saturation kinetics and competitive inhibition

Back 55

T

Front 56

Do passive transporters have a water filled pore? specific binding site for the substrate? are they divided into subunits?

Back 56

no ; yes ; no

Front 57

T or F passive transporters do not have an equal binding affinity for the substrate from both sides of the membrane

Back 57

F

Front 58

what is the rate liming step for passive transporters? do they exhibit stereospecificity?

Back 58

conformational change ; yes

Front 59

in a passive transporter, when is a molecule released from it's binding site?

Back 59

after a conformational change has exposed the binding site to the cytosol

Front 60

how do the helices in a gluocse transporter interact w/ the glucose molecule?

Back 60

the side chains of the AA in the helices (such as asparagine, glutamine, serine, and threonine) form hydrogen bonds w/ the glucose molecule

Front 61

glucose transporters bind to D glucose, galactose, and mannose in what order (from greatest to smallest)

Back 61

D-glucose > D-mannose > D-galactose

Front 62

1. how do most cells transport glucose?
2. hos does the intestine and kidney transport glucose?

Back 62

1. passively
2. actively

Front 63

how many eukaryotic passive glucose transporters are there?

Back 63

at least 5 (GLUT 1-5)

Front 64

1. which gluocse passive transporter is regulated by insulin?
2.where is this glucose transporter found?

Back 64

1. GLUT-4, insulin regulates how many GLUT-4 are in the cells membrane, if insulin is high there will be more GLUT-4 in the membrane, low insulin causes GLUT-4 to go back inside the cell
2. it is in fat and skeletal muscle

Front 65

how many AA transporters are there and what type are they?

Back 65

5 or more passive and active transporters

Front 66

how are nucleic acids transported?

Back 66

by a single passive transporter

Front 67

what are 2 examples of how passive transporters are controlled?

Back 67

1. ligand binding
2. 2nd messenger cascades such as phosphorylation of the transporter

Front 68

what is primary active transport?

Back 68

the unidirectional movement of ions or molecules through a membrane against their electrochemical gradient. it uses metabolic energy (usually ATP) to provide the energy for the movement

Front 69

T or F Primary active transport does not have a permanent water filled pore

Back 69

T

Front 70

Do primary active transporters have binding sites for the substrates? exhibit saturation kinetics?

Back 70

yes to both

Front 71

what are the 3 classes of primary active transporters?

Back 71

1. P class (phosphorylation)
2. V class (vesicle)
3. F class (formation)

Front 72

what kind of pumps does the P class of primary active transporters include?

Back 72

1. Na+/K+
2.Ca++ (several types)
3. H+
4. H+/K+
5. K+

Front 73

what kind of pumps does the V class of primary active transporters use?

Back 73

H+ pumps, H+ is carried in a vesicle

Front 74

what kind of pumps does the F class of primary active transporters use?

Back 74

H+ pumps which are located in the inner mitochondrial membrane and used to make ATP. H+ pump driven backwards by the hydrogen ion gradient produced by the electron transport system

Front 75

in the Na+/K+ pump, how many binding sites are there for Na+ and how many are there for K+?

Back 75

3 for Na+ and 2 for K+

Front 76

does phosphorylation of the Na+/K+ pump cause the binding sites to move to the interior of the cell or outside of the cell?

Back 76

phosphorylation of the Na+/K+ causes the binding sites to move to the outside of the cell; dephosphorylation causes the binding sites to move to the inside of the cell

Front 77

explain what the affinities are for Na+ and K+ when the binding site are exposed to the inside and outside of the cell

Back 77

when the binding sites are exposed to the outside of the cell the affinity for K+ is high and the affinity for Na+ is low; when the binding sites are exposed to the inside of the cell the affinity for Na+ is high and K+ low

Front 78

what phosphorylates and dephosphorylates the Na+/K+ pumps?

Back 78

ATPase on the pump phosphorylates the pump causing the binding sites to become exposed to the outside of the cell; binding of K+ initiates dephosphorylation of the pump causing the binding sites to become exposed to the interior of the cell

Front 79

how is the P class transporter controlled?

Back 79

1. # of transporters in membrane
2. phosphorylation of transporter by 2nd messenger cascades
3. Ca++ binding
4. allosteric binding of various other ligands

Front 80

Na+ is always transported where?

Back 80

into the extracellular fluid, so Na+ helps control extracellular fluid volume

Front 81

explain how the V class of transporters work

Back 81

they pump H+ ions into lysosomes, secretory and storage vesicles to lower the pH in these vesicles. They are found on the osteoclast's plasma membrane on the side of the cell next to bone -dissolving bone mineral. they are composed of several subunits and use ATP but do not have a phosphorylated intermediate

Front 82

what kind of transporter is the nuclear pore complex? what does it transport?

Back 82

it is a primary active transporter that transports proteins into the nucleus and RNA molecules out of the nucleus

Front 83

the only transporter in the nuclear membrane is what?

Back 83

the nuclear pore complex

Front 84

the nuclear pore has what type of channels?

Back 84

ion and H2O

Front 85

what are the 5 steps in nuclear pore transport of proteins?

Back 85

1. nuclear location sequence
2. targeting
3. docking
4. translocation (GTP used)
5. release of receptor

Front 86

how does a cell know where a certain protein needs to go?

Back 86

AA sequence (signal sequence - nuclear location sequence), 3D shape, and subunits attached

Front 87

in a secondary active transport is metabolic energy directly used in the transport process?

Back 87

no, energy is derived from the gradient of another ion or molecule (Driving gradient). the driving gradient supplies the energy for transport of the 2nd type of ion or molecule

Front 88

in secondary active transport, what determines the direction of the transport of the 2nd ion or molecule?

Back 88

direction of the driving gradient determines the direction of transport of the 2nd ion or molecule

Front 89

describe what happens in symport secondary active transport

Back 89

one type of ion or molecule moves through a membrane down its concentration gradient as another type of ion of molecule is transported against its gradient in the same direction as the first

Front 90

describe what happens in antiport secondary active transport

Back 90

as one type of ion or molecule moves through a membrane down it's concentration another ion or molecule is transported through the membrane in the opposite direction

Front 91

using sodium to transport calcium is what type of transport?

Back 91

antiport cotransport, the direction of calcium transport is determined by the sodium gradient

Front 92

using Na+ to transport glucose is what type of transport?

Back 92

symport

Front 93

using Na+ to transport amino acid uses what type of transport?

Back 93

symport

Front 94

using Na+ to transport H+ uses what type of transport?

Back 94

antiport

Front 95

the movement of ADP and ATP uses what type of transporter ?

Back 95

antiport

Front 96

what is transcellular transport?

Back 96

transport of ions or molecules directly through a cell. the transport is active on one side of the cell and passive on the other side. examples - absorption of ion and nutrients by the small intestine and reabsorption of ions and nutrients by the renal tubules

Front 97

what is paracellular transport?

Back 97

the movement of substances between cells that have leaky junction

Front 98

active transport of these ions always occurs in what direction?
1. Na+
2. Ca++
3. H+
4. K+

Back 98

1. out of the cell
2. out of the cell
3. out of the cell
4. into the cell

Front 99

what are 3 types of bulk transporters?

Back 99

1. phagocytosis - plasma membrane zippered around particle to form vesicle
2. endocytosis - water and solutes
3. receptor mediated endocytosis