Bsci 330 Exam 2 Set 2

Front 1

techniques for membrane fluidity

Back 1

1)Fye and Ediden exp (not in real cells)

2)FRAP (real cells)

3)single particle tracking (real cells)

Front 2

single particle tracking

Front 3

what about integral membrane proteins with large extracellular domains?

Back 3

can find themselves entangled in the extracellular matrix

Front 4

proteins anchored to membrane will what?

Back 4

not diffuse

Front 5

just beneath membrane lies what?

Back 5

network of fibrous proteins...membrane skeleton

Front 6

what is the membrane skeleton often formed by?

Back 6

spectrin and actin filaments and associated proteins

Front 7

what is the makeup of A RBC membrane skeleton?

Back 7

spectrin
actin
tropomyosin
ankyrin
Band 4.1

Front 8

what happens as a reslt of anchoring of proteins and mobility barriers presented by the membrane skeleton?

ex?

Back 8

cells can maintain plasma membrane domains that differ in composition and function

epithelial cells in gut have:

Front 9

what do most simple diffusion equations describe?

Back 9

net influx or efflux

Front 10

diffusion

Back 10

net movement of solute down its electrochemical gradient

Front 11

electrochemical gradient

Back 11

sum of concentration gradient and electrical gradient

Front 12

concentration gradient

Back 12

difference in concentration of a solute in one region compared to another

Front 13

electrical gradient

Back 13

force acting on a charged solute molecule as it moves from a region with one electrical potential to a region with a deifferent electrical potential

Front 14

is diffusion spontaneous or non-spontaneous

Back 14

spontaneous...negative ΔG

Front 15

what causes movement of substances across membranes-diffusion- to be spontaneous and have a -ΔG

Front 16

Why do we have to introduce charge and electrical potentials into our concept of diffusion?

Front 17

Direction of net movement of uncharged solute across a cell membrane is what?

Back 17

always down solute's concentration gradient

Front 18

ΔG relating to diffusion of uncharged molecules

Front 19

ΔG relating to diffusion of charged molecules

Front 20

What can ΔG for ion movement across a membrane tell us?

Back 20

1) Is the movement of a solute or ion across a membrane passiveor active?

Front 21

what does ΔG (net movement into cell) not tell us

Front 22

In order for solutes to enter cell....

Back 22

must pass through the partial permeability barrier created by the membrane

Front 23

lipids, small uncharged polar molecules, large uncharged polar molecules, charged molecules of any size and how they diffuse through membrane

Front 24

what is the name relating to diffusion given to the membrane?

Back 24

semipermeable barrier...must be able to maintain concentration differences between the internal and external environments

Front 25

health of cell and diffusion

Back 25

requires that material transport be a regulated process

Front 26

What is the difection of movement of material across a membrane?

Back 26

moves in both directions

Front 27

most cell products are what?
...importance with diffusion

Back 27

charged or polar....cells have evolved membrane proteins whose function is to transport small molecules and ions

Front 28

2 basic types of movement across cells

Back 28

-passive transport
-active transport

Front 29

passive transport

Back 29

In passive transport, molecules move spontaneously down their electrochemical gradient (–ΔG).

Front 30

active transport

Back 30

In active transport, energy (ATP) is consumed to move molecules up their electrochemical gradient –similar to a “coupled reaction”

Front 31

simple diffusion

Back 31

molecules just diffuse across the bilayer down its electrochemical gradien-no transport protein or channel is involved

Front 32

three factors combine to limit simple diffusion

Front 33

can simple diffusion be saturated?

Back 33

no..there is no limit to the net flux as the electrochemical gradient increases

Front 34

simple diffusion of water across membrane?

Back 34

osmosis

Front 35

how does osmosis work

Back 35

water goes from area of low solute concentration to one of higher solute concentration

cell volume and turgor pressure can be controlled by solute concentration...turger pressure is greater the more hypotonic the environment is

Front 36

3 osmosis conditions

Back 36

a

Front 37

mneumonic for osmosis

Back 37

hypooooooo.....the o looks like a filled up cell

Front 38

what do pore or channel proteins do?

Back 38

allow ions, charged and some uncharged polar molecules to cross the membrane by passive diffusion

...not simple diffusion since a channel protein is involved

Front 39

Ion channels can allow what with respect to flux

Back 39

bidirectional flux or specific ions... Na, K, Ca, Cl across a membrane down their electrochemical gradients

Front 40

channel protein water can move through

Back 40

aquaporin

Front 41

channel structure

Back 41

Front 42

are ion channels selective or not selective?

Back 42

very selective-only allow one type of ion to pass through

Front 43

what does a pore (ion channel) look like

Front 44

describe what happens to ion as it enters goes through channel

Front 45

are ion channels always open?

Back 45

no...Ion channels are not always open -the central pore can be “gated”open and shut by changes in channel conformation.

Front 46

change in conformation that opens a channel can be driven by?

Front 47

a given channel protein can be named by

Front 48

ligand gated channels

Front 49

extracellular ligands

Back 49

water-soluble hormones, neurotransmitters

Front 50

intracellular ligands

Front 51

resting membrane potential of most animal cells and plant cells

Back 51

-60 to -70mV

Front 52

ligands do what to membrane potential?

Back 52

change it by allowing stuff in or out of the gate.

Front 53

is the movement of ions saturable through a pore?

Back 53

no; however, binding of the ligand is and it displays affinity to the receptor: similar to michaelis-menton equation..

Kd=1/affinity of the channel for the ligand

%with ligand bound=[ligand]/(Kd+[ligand])*100%

Front 54

Kd=

Back 54

K-1/K1

or

1/affinity of the chanel for the ligand

Front 55

for many channels________ eqyals % open

Back 55

percent chanels with ligand bound

Front 56

picture of ligand gated mechanism

Back 56

.

Front 57

voltage gated ion channels do what?

Back 57

open up when there is a change in the membrane potential

Front 58

generally speaking, if the membrane potential starts at -70mV and becomes more positive....what will happen?

Back 58

it will let stuff in

Front 59

what creates action potential in nerve cells?

Back 59

voltage-dependent sodium and potassium chanels

Front 60

what happens if voltage gated ion channels Ca2+ are present?

Back 60

will allow calcium ions to flow into the cell.

Front 61

what does the transmembrane helices S4 contain and why is this importatn?

Back 61

it contains many positively charged arginine residues ....if the cell becomes positively charged inside...these residues will repel the positive charge, move through the membrane, and create a conformational change that will open the pore.