L1 - Introduction

Question 1

Function of the membrane

Answer 1

Divide EC and IC environments

Question 2

PM composition

Answer 2

42% lipid
55% protein
3% carbohydrate

Question 3

Na is ________ inside and ________ outside

Answer 3

High outside

Low Inside

Question 4

K is _______ inside and __________ outside

Answer 4

High inside

Low outside

Question 5

Ca is _________ inside and _______ outside

Answer 5

High on the outside

VERY low inside

Question 6

Function of bicarbonate

Answer 6

Buffer against pH changes

Question 7

Usually Cl is _______ inside and __________ outside

Answer 7

Low outside

High Inside

Question 8

What is special about the IC Cl value of Cl secreting cells

Answer 8

High inside

Question 9

What is the concentration of PO4(2-) inside the cell

Answer 9

High

Question 10

Why is PO4(2-) high inside of the cell

Answer 10

For ATP production

Question 11

How do lipid soluble molecules move across the membrane

Answer 11

Diffusion

Question 12

To move across the membrane small molecules and ions require

Answer 12

Transport proteins

Question 13

Method of transport across the membrane for large molecules

Answer 13

Endocytosis

Question 14

Characteristics of active transport

Answer 14

Using pumps

ATP driven

Question 15

What is the turnover like for active transport

Answer 15

Low

Question 16

What does the term ‘directly active mean’

Answer 16

Needs to energy from ATP hydrolysis directly

Question 17

Active transport occurs in the _________ or ___________ an electrochemical gradient

Answer 17

Absence or against

Question 18

What does passive transport depend upon?

Answer 18

Electrochemical gradient

Question 19

What is the turnover like for passive transport

Answer 19

Very high

Question 20

Passive transport is _________

Answer 20

Highly selective

Question 21

Why is a maximum rate of passive transport acheived

Answer 21

Transporters become saturated - only a limitted number

Question 22

Describe a symporter mechanism

Answer 22

Two solutes same direction

Question 23

Describe a uni porter

Answer 23

One solute one direction

Question 24

Describe an antiporter

Answer 24

Two solutes in opposite directions

Question 25

What is the mechanism for carrier mediated transport

Answer 25

Binding of solute to highly selective site Conformational change Release of solute onto the other side

Question 26

What is the Na/Glucose cotransporter an example of

Answer 26

Co transport

Question 27

Why is Na/Glucose co transport called secondary active?

Answer 27

Relies on the inward gradient for Na generated by the Na/K ATPase

Question 28

Why is the Na/K ATPase known as ubiquitous

Answer 28

Found in every cell of the body

Question 29

One example of a cell where the Na/K ATPase is not found

Answer 29

The red blood cell of the dog

Question 30

Structure of the Na/K ATPase

Answer 30

Tetramer | 2 alpha 2 beta

Question 31

What does electogenic mean

Answer 31

Charge creating

Question 32

Why is the Na/K ATPase an electrogenic form of transport

Answer 32

Creates a charge (3+ out for only 2+ in)

Question 33

What is the movement rate of ions through a channel per second

Answer 33

10^6 / 10^8

Question 34

Who developed the patch clamp technique

Answer 34

Nehr and Sakman

Question 35

Describe the patch clamp technique

Answer 35

Allows a very small current flowing through an ion channel to be measured directly

Question 36

Describe the cell attached patch clamp technique

Answer 36

Pipette sealed to membrane to form a gigaseal | Allow recording of currents through 1 or a few ion channels

Question 37

What is a voltage clamp

Answer 37

Pulse of suction to rupture membrane so electrode now measures the total current flow across the cell membrane

Question 38

What does a voltage clamp measure

Answer 38

Total current flow across a cell membrane

Question 39

Uses for patch clamping

Answer 39

Identification Regulation Physiological Function

Question 40

Recall the equation for patch clamping

Answer 40

I = N . P(_O) . g (Vm- Ei)

Question 41

In the patch clamp equation what does I represent

Answer 41

Total current carried by population channels

Question 42

In the patch clamp equation what does N represent

Answer 42

Number of channels

Question 43

In the patch clamp equation what does Po represent

Answer 43

The open probability

Question 44

In the patch clamp equation what does g represent

Answer 44

Single channel conductance

Question 45

In the patch clamp equation what does Vm represent

Answer 45

The membrane potential

Question 46

In the patch clamp equation what does Ei represent

Answer 46

Equillibrium potential for ion i

Question 47

What is meant by 'molecular families of ion channels'

Answer 47

That many variations of ion channels found throughout the body So a mutation in a gene coding a K channel in the ileum may not effect K ion channels in the brain for example

Question 48

Properties of the Kv channel

Answer 48

Voltage gated K channel 6 transmembrane domains 4th transmembrane domain is +vely charged N + C terminus insdie of the cell

Question 49

Properties of the Na V channel

Answer 49

Voltage gated sodium ion channel 3 subunits a1 b1 b2 24 transmembrane domains Tm domain in each b1 b2

Question 50

Properties of the Kir channel

Answer 50

Inwardly rectifying | 2 transmembrane domains

Question 51

Properties of CFTR Cl- channel

Answer 51

12 transmembrane domains | 2 groups of 6

Question 52

Describe the K channel crystal structure

Answer 52

KcsA (bacterial K channel) homolgous to Kir mammalian family X ray diffraction analysis showed that there is more than one K ion in the pore at any one time

Question 53

What were the main results of the X ray diffraction analysis on the KscA channel

Answer 53

Showed more than one K ion in the pore at any one time