Transporters, Ion channels and Pores

Question 1

what does passive transport rely on

Answer 1

• permeability
• conc gradient
  rate is proportional to conc gradient

Question 2

molecules that can pass through bilayer

Answer 2

• small
• uncharged
• hydrophobic (02, C02, N2, H20 - EXCEPTION)

Question 3

how to increase permeability of membrane

Answer 3

add protein carriers

Question 4

name some important roles of transport processes

Answer 4

-maintain ionic composition
-maintain pH
-regulate cell volume
-generic ion gradient
conc of metabolic fuels and building blocks

Question 5

describe how f.d via ion channels can work

Answer 5

eg, acetylcholine binds to protein and it forms a passage

Question 6

ATP sensitive K channel

Answer 6

when there is a high ATP channel closes so stops K passing through

Question 7

voltage sensor carrier

Answer 7

cells are always negative on the inside relative to the outside
so when there is a change in voltage the channel opens

Question 8

where does energy come from for Active transport

Answer 8

ATP hydrolysis

Question 9

channels

Answer 9

form a hydrophilic pore for ions to move across

Question 10

difference between K and NA in intracellular and extracellular fluid

Answer 10

K in high in intracellular
K low in extracellular

Question 11

conc gradient of Na

Answer 11

higher on outside of cells (145-12) mM

Question 12

conc gradient of K

Answer 12

higher on inside the outside (140-4) mM

Question 13

conc gradient of Ca

Answer 13

higher on the outside (1.5mM-0.1uM)

Question 14

conc gradient of Cl

Answer 14

higher on outside (123-4.2)mM

Question 15

osmole

Answer 15

solutions ability to create osmotic pressure and thus affect movement of water

Question 16

what does 1 mol of glucose equate to

Answer 16

1 osmolar in 1L

Question 17

what does 1 mol of NaCl equate to

Answer 17

2 osmolar in 1L

Question 18

what does 1 mol of CaCl2 equate to

Answer 18

3 osmolar in 1L

Question 19

osmolality

Answer 19

conc of solution expressed in osmoses per kg

Question 20

osmole/kg

Answer 20

1 osmole/kg = 1 osmole/L = 1000milliosomole/L

Question 21

diffusion of water

Answer 21

hypertonic - hypotonic across semi permeable membrane

Question 22

how to stop flow of water

Answer 22

add pressure

Question 23

Plasma membrane Ca2+ ATPase

(PMCA)

Answer 23

primary active transporter
energy released the reaction ATP –> ADP + Pi releases Ca against its conc gradient and moves it out the cell H into the cell
(Can also get Mg)

its a high affinity, low capacity transport

Question 24

ATP synthetase
F1F0-ATPase

Answer 24

uses proton gradient in electron transport chain and energy to allow protons to re enter matrix to drive synthesis of ATP
so is a primary active transporter in reverse mode

Question 25

Uniport

Answer 25

where there is one transported molecule through a protein

Question 26

Symport

Answer 26

2 proteins travelling through a protein in the same direction

(example of cotransport)

Question 27

antiport

Answer 27

2 molecules pass through protein in different directions

(example of cotransport)

Question 28

Na/K pump

Answer 28

uses energy from hydrolysis of ATP to pump
- 3 NA out of cells
- 2 K into cells
both against conc gradient
antiport

Question 29

what is a primary active transporter

Answer 29

uses ATP to pump ions

Question 30

Describe this sodium pump

Answer 30

there is a P-type ATPase phosphorylated on the aspartate

alpha subunit - contains binding site for Na/K/ATP

beta subunit - needed for alpha subunit to be tranported to the plasma membrane. it is a glycoprotein

this is needed to create an ion gradient for secondary active transport

Question 31

secondary active transport

Answer 31

driven indirectly by the energy released by hydrolysis of ATP to ADP

Question 32

what part of the Na/K pump is responsible for membrane potential

Answer 32

diffusion of K through channels

Question 33

Na - Ca exchanger

Answer 33

secondary active transport

dissapation of the Na gradient drives transport of Ca out of the cell

antiport ( Ca out of cell and Na in)

low affinnifty, high capacity - removes most of the Ca

Question 35

Na - H exchanger

Answer 35

uses the Na / K pump to move H ions out of the cell

Question 36

Na- Glucose co transport

Answer 36

glucose moves into the cell against ints conc gradient

symport

Question 37

Cystic Fibrosis transport

Answer 37

the Cl receptor is damaged ao Cl cand move out of the cell and water cant move with it so there is a bbuild up of mucus

Question 39

SERCA

Answer 39

similar to PMCA but the Ca enters the endoplasmic recticulum

high affinity, low capacity

Question 40

mitochondrial Ca uniports

Answer 40

facilitated transport

operates at a high Ca conc to buffer potentially damaging levels of Ca

Question 41

Na/Ca exchanger