Regulation of cell pH

Question 1

Normal pH inbody

Answer 1

between 6.8 and 7.2

Question 2

Lwer and higher in what?

Answer 2

Lower in lysosomes

Higher in mitochondira

Question 3

Macromolecules as intracellular buffers

Answer 3

Proteins that have a weak acid (H2N) and base (OOC) groups on them
Minimise fluctuations and adjust pH
H2N + H+ —> H3N+
-OOC + H+ —> COOH

Question 4

CO2 / BICARBONATE buffer

Answer 4

‘Open buffer’ as CO2 can enter and leave cell easily.
CO2 + H2O H+ +HCO3
(If increase H+ in cell then equilibrium shifts to left, CO2 production increased so leaves the cell)

Question 5

If H+ was allowed to diffuse completely via electrochemical gradient…

Answer 5

The gradient would be -60mv
Using nernst eq this would be pH 6.4
However pH in cell is 7.2 therefore H+ has to be actively transported out of cell

Question 6

How do we measure PH

Answer 6

Use BCEF fluorescent indicator
Excite with 440 and 490 blue light.
Meaure 530 green light emission

Question 7

How do we measure pH using NH3

Answer 7

Add NH4Cl to cell

This alkalinizes as it turns into NH3, which will mop up all the H+ in the cell —> make NH4+ in cell.