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Flashcards in Membrane Properties Deck (51):
1

Membrane proteins can be categorized according to:

1. Structure
2. Function

2

What are the "structure" proteins

1. Integral; span both layers
2. Peripheral proteins; found only on one side

3

What are the "function" proteins

1. structural proteins
2. membrane transporters
3. membrane enzymes
4. membrane receptors

4

which proteins do the membrane transporters consist of

1. Carrier proteins: change conformation
2. Channel proteins: form open and gated channels

5

Where are structural proteins found in

1. cell junctions
2. cytoskeleton

6

What are membrane enzymes active in

1. metabolism
2. signal transfer

7

what are membrane receptors active in

receptor mediated endocytosis, signal transfer and and open and close chemically gated channel

8

Na/K pump more of an enzyme bc uses energy of ATP, hydrolyzes it and changes conformation of :

carrier

9

Electrical potentials are generated across the membranes of neurons and all cells bc:

1. There are diff's in the conc's of specific ions across nerve cell membranes
2. the membranes are selectiviely permeable to some of these ions.

10

What is the ion conc. gradients are est by which proteins

active transporters; actively move ions into/out of cell against their conc gradient.

11

The selective permeability of membranes is due to:

ion channels; allow only certain kinds of ions to cross the membrane in the direction of their conc gradient.

12

Channels and transporters work ____each other, and in doing so they genereate the ___ ___ ___, action potentials, the synaptic potentials, and receptor potentials that trigger the action potentials

against; resting membrane potential

13

The cell body and the dendrites is called the _____ domain

somatodendritic

14

The axon and nerve termini is called the ____domain

axonal

15

what is a ligand gated ion channel

they need something to bind to it (ligand aka neurotransmitter) in order to open/close

16

Ligand gated channels are mainly located where

somatodendritic domain

17

what are voltage gated Na/K+ channels

Requires a change in electrochemical potential in order to open/close it.

18

Where are voltage gated channels mainly

in the axonal domain

19

How come action potentials don't go the opposite way? ( Nerve termini -->cell body)

specific spatial distribution of Na/K+ voltage gated channels

20

You will always see a greater amount of ____ions intracellular and lower amount of ___ and ___ ion

K+; Cl- and Na+

21

All fluids and cells maintain __ ____ which means that the # of pos charges = # of negative charges

bulk electroneutrality

22

What are the ionic gradients used for

1. Used by secondary active transport processes
2. Used by excitable cells, allowing production of action potentials

23

Fixed proteins which have a lot of negative charges are found in which part of the cell

inside

24

There is a slight ____charge inside the cell relative to outisde of the cell

inside

25

While all cells maintain a membrane potential, the actual voltage varies by cell type and is influenced by _____concentration gradients and _____permeability to those ions

ionic; membrane

26

In most cases, the resting membrane potential is due to leaking of ____ion out of the cell without a counter ion balancing the charge

K+

27

cells are not + or - charged. Areas close to plasma membrane has a slight electrical potential diff between outside and inside. The charges are affected by two diff forces:

1. how much ions you have on other side
2. how much your membrane is permeable

28

The driving force for passive transport across the membrane is influenced by a _____gradient for nonelectrolytes

concentration

29

The driving force for passive transport across the membrane is influenced by concentration gradient and _____gradient for ions

electrical

30

Ions come into electrochemical equilibrium where net flux of the ion may = 0, even if there is still a ____gradient

concentration

31

If the membrane potential is negative inside, there will be a _____ driving force than expected from the conc. gradient alone b/c the inside negatic charge attracts the + charged cation. The rate of the flux will be ____

greater; greater

32

If the conc of ions are the same on both sides what would happen?

nothing

33

If there is a higher conc on one side and it is permeable it will go on which side?

the side that has less

34

What are pseudo cellular conditions

When you have different molecules on both sides of membranes, but only one (usually K+) is permeable. You don't get as much movement as you would if there were same molecules on each side.

35

What does the Nernst eqn show us

allows us to predict the membrane potential at which a given ion will be at eq. It can determine the relative driving force for ion flux and which way an ion will move across the membrane

36

Is the eq potential for Na+ positive or neg? What about K+ and Cl-

positive; negative; negative

37

Na goes ___ K goes ___ and Cl goes ____

in; out; out

38

Which ion is most permeable?

K+ is the main ion that we allow to permeate through selectively permeable membrane

39

If the gradient for a given ion /permeability for an ioc across the membrane changes what else changes?

the membrane potential! AKA Vm

40

What is the difference between Goldman Hodgkin Katz equation and Nernst equation.

You can put diff conc ( in and out) for diff ions you have to get direct value for membrane potential which is very close to what you see in vivo (living cell) than Nernest equation. Nernst equation gives you theoretical equilibrium potential for only one ion.

41

What is equilibrium potential

A theoretical value of what the Vm will be when/if the ion is at equilibrium. eq potential is what cells are aiming for when they're generating membrane potential but it doesnt reach that high bc there are a lot of ions involved as well.

42

what is membrane potential

a REAL value that can be measured.

43

What is the voltage of a membrane a function of

the resistance of the membrane to ion flow and the actual flow (current)

44

Resistance is:

futile

45

What is conductance

ion flow rate; the inverse of resistance

46

What is the purpose of a patch clamp

measures ion flow through a single channel; place tip of glass pipette on cell membrane and pick up selective channels. If it opens/closes you can record the current and voltage.

47

what is current in a normal living cell

ions that create electrical impulses

48

What are the diff ways of patch clamping.

1. putting on channel and recording it.
2. rupture the cell by suction which opens the whole cell to easily record currents through the whole cell.
3. You can split it off and have one specific channel
4. You can invert it; remove glass pipette which removes phospholipids and drags a channel with it. When it anneals, you have a channel and the inside of electrode is like inside of cell

49

What does openings of multiple channels create

causes stepwise increases in current.

50

what is the magnitude of the TEPD proportional to

the tightness of the tight junctions

51

How do you calculate TEPD

Vb - Va