Biological Membranes and transport ions and pores

Question 1

What types of movement can membrane proteins do?

Answer 1

Conformational change
Rotation
Lateral diffusion

Question 2

How does temperature affect membrane fluidity?

Answer 2

As temp increases membrane fluidity increases due to increased kinetic energy

Question 3

What are integral proteins?

Answer 3

Embedded within the phospholipid bilayer
Referred to as transmembranous
Extensive hydrophobic domain which interacts with the hydrophobic tails

Question 4

What are peripheral proteins

Answer 4

Bound to the surface of the membrane via electrostatic and hydrogen bonds

Can become dissiociated with the membrane by pH disturbances

Question 5

What can pass readily through the lipid bilayer?

Answer 5

Small uncharged molecules and polar and hydrophobic

Question 6

What is the difference between simple diffuse and facilitated diffusion?

Answer 6

Simple diffusion isn’t saturated, due to a limited number of channels in the membrane facilitated diffusion will reach a max rate eventually

Question 7

What are ligand gated channels

Answer 7

Open and close when a chemical signalling molecule binds to it

Question 8

What are voltage gate channels

Answer 8

Open in response to changes in membrane potential

Question 9

What are mechanically gated channels

Answer 9

Open in response to mechanical stretch of the membrane- mechaoreceptors in skin

Question 10

What is primary active transport?

Answer 10

Where energy is derived directly from ATP hydrolysis

Question 11

What is secondary active transport

Answer 11

Known as co transport

Utilises energy from a. Pre-existing electrochemical gradient

Question 12

What are symports? Ant ports?

Answer 12

Where the ions/ molecules flow through the transporter in the same directions

Where they flow in opposite directions

Question 13

What is the Na+/H+ exchanger

Answer 13

It is an acid extruder which alkalinises the cell.

It uses a pre-existing Na+ gradient to move sodium into the cell and hydrogen out of the cel.

Important in the kidney tubule where it can be targeted by amiloride. DIURETIC

Question 14

What is the Na+/HCO3- co-transporter?

Answer 14

Causes alkali influx and therefore alkanisises the cell

Uses pre-existing Na+ gradient to move both 1Na+ and 3 HCO3- into the cell

Question 15

What is the anion exchanger

Answer 15

Aka band 3

Alkali extruder acidifies the cell

Moves 1Cl- in and 1 HCO3- out

Found on erythrocytes and kidney tubules

Question 16

Which transporter is responsible for extruding the majority of Ca2+ after a rise in intracellular calcium?

Answer 16

The Na+/Ca2+ exchanger

Moves 3Na+ into the cell for every 1 Ca2+ out

It has a low affinity but a high capacity

Question 17

What does the value of delta G tell us?

Answer 17

Whether the transport is passive or active

Negative- passive
Positive- active

Question 18

Distribution of water

Answer 18

2/3 intracellular

1/3 extracellular
Of that 25%- plasma
75%-interstitual fluid

Question 19

What is the concentration of sodium inside and outside the cell?

Answer 19

Inside- 12mM

Ouside - 145mM

Question 20

Conc of chloride ions

Answer 20

123mM out

4.2mM in

Question 21

Conc of calcium

Answer 21

1.5mM out

10 to the power -7 in

Question 22

Conc of potassium

Answer 22

140mM inside

4.5 mM out

Question 23

What is isotonic

Answer 23

Equal solute equal water

Question 24

What is osmole

Answer 24

Measure of solutions ability to create osmotic pressure and this affect the movement of water
Proportional to the number of osmotic particles in solution

Question 25

What is osmolality

Answer 25

When the concentration of a solution is expressed in osmoles per kg of water Osmolar concentration of a solution is referred to as osmolalilty

Question 26

What is osmotic pressure

Answer 26

The prevention of water moving by applying pressure The pressure applied to stop the flow of water

Question 27

How does the plasma membrane Ca2+ ATPase work

Answer 27

An example of a primary active transporter Transport calcium out fo the cell using ATP

Question 28

What is the sodium potassium ATPase pump

Answer 28

3 sodium out for 2 potassium in Generate ion gradients that allow secondary active transport And action potentials Only a small contribution to resting membrane potential

Question 29

What is responsible for membrane potential

Answer 29

Potassium diffusion through channels `

Question 30

What is the sodium glucose co transporter

Answer 30

Entry of sodium ions provides the energy for he entry of glucose against its concentration gradient Uses ATP Symport

Question 31

How does serca control resting Ca2+

Answer 31

Serca accumulates Ca2+ into the SR/ER It has a high affinity but a low capacity

Question 32

How is calcium concentration controlled by active transport

Answer 32

Secondary active transport Sodium/calcium exchange anti port Low affinity high capacity Removes most calcium

Question 33

How is cell volume regulated

Answer 33

Transport of osmotically active ions Cell swelling- extrude ions ‘ Cell shrinking- influx ions Water will flow the ions

Question 34

Name the 2 primary active transporters that help maintain or decrease intracellular ca2+ levels

Answer 34

PMCA SERCA

Question 35

In ischaemia how does the NCX contribute to more damage

Answer 35

During ischemia, the lack of oxygen prevents the production of ATP. Without ATP, the Na-K-ATPase is inhibited and leads to intracellular concentration of Na rising. This leads to the reversal of the NCX causing it to exchange intracellular Na for extracellular Ca. This reversal leads to accumulation of intracellular Ca, which is toxic to the cell, therefore causing cell death or necrosis.