Cellular pH

Question 1

What are 2 ways of measuring cellular pH?

Answer 1

1.Using micro-electrodes- measure V across membrane, (calibrate electrodes beforehand)
2.Fluorescent indicators
indicator excited with light of a specific wave length

Question 2

What are the 3 main ways of controlling pH?

Answer 2

1. Buffering
2. Acid extrusion
3. Acid loading

Question 3

What is the acceptable range of pH?

Answer 3

7.35-7.45

Question 4

What does buffering involve?

Answer 4

NH2/COOH groups on buffering proteins- reversibly consuming or releasing protons

Question 5

What is acid extrusion?

Answer 5

Na+ into cell, H+ out of cell

Relies on inward Na+ gradient set up by Na+/K+ pump

Question 6

What does the NHE1 housekeeping gene code for, and what does it do?

Answer 6

NHE protein= Na/H exchanger

Question 7

What is acid loading?

Answer 7

Cl- into cell, HCO3- out of the cell

Relies on inward gradient set up by Na+/K+ pump

Question 8

What is a similarity of both the NA/H and Cl/HCO3 exchanger?

Answer 8

Both are modulated by pH
NA/H exchanger- stimulated at acidic pH
CL/HCO3 exchanger- stimulated at alkaline pH

Question 9

How does movement of bicarbonate out of the cell increase cellular pH?

Answer 9

Removing HCO3 from the cell leaves H+ behind

H2CO3-> HCO3- + H+

Question 10

How does an decrease in pH change the NHE protein?

Answer 10

H+ binds to the NHE protein and causes a conformational change, leading to an increase in activity