Cell signalling 1

Question 1

How is Na+ and K+ ion concentrations in a cell

Answer 1

Na+ ions high outside
K+ ions high inside the cell

Question 2

Describe the two ways ion transport can be effected

Answer 2

Ion transport can be done through passive and active means through channel proteins ( passive ) and carrier protein ( passive or active )

Question 3

How are ion gradients generated across a plasma membrane ? name the proteins involved

Answer 3

Ion gradients are generated by active transport through the use of P-type ATPases and coupled secondary transport ( exchangers ) ( passive )

Question 4

How is the Na+ and K+ ion gradient established ?

Answer 4

Sodium-potassium atpase

Question 5

How is the Ca2+ pump gradient generated across the plasma membrane and the Endoplasmic reticulum ?

Answer 5

The Ca2+ gradient is generated in the plasmembrane through PMCA( Plasma membrane calcium atpase ) and through NCX( sodium calcium xchanger …an antiport )
The Ca2+ gradient is generated across the ER by SERCA ( Sarcoendoplasmic reticulum calcium atpase)

Question 6

How is the pore domain of an ion channel specialised for its job ?

Answer 6

The pore domain is just the right size for a K+ ion to pass through acting as an ion-selective filter. It can be stabilized with 4 bonds which makes it energetically favourable

Question 7

Describe how the voltage-sensing domain of an ion channel works

Answer 7

The voltage-sensing domain of an ion channel has regularly spaced +ve residues R and K. The domain changes shape when it interacts with the ion opening of the channel