CELLULAR PH

Question 1

WHAT IS THE EQUATION OF PH

Answer 1

PH=-LOG10[H+]

Question 2

WHY IS PH IMPORTANT

Answer 2

1. PROTONS ARE AN IMPORTANT SECOND MESSENGER

2. PH CAN ACTIVATE/INACTIVATE PROTEIN FUNCTION FOR REGULATION

Question 3

DESCRIBE A METHOD OF MEASURING IC PH

Answer 3

1. MICROELECTRODES
   TWO ELECTRODES PIERCE THE MEMBRANE. V1 CONTAINS H+ SENSITIVE RESIN SO MEASURE EVERYTHING EXCEPT H+.
   VOLTAGE DIFFERENCE BETWEEN V2 AND V1 IS PROPORTIONAL TO PH.

Question 4

DESCRIBE A SECOND METHOD OF MEASURING IC PH

Answer 4

2. INDICATORS
   CELLS CAN BE LOADED WITH AN INACTIVE FORM OF INDICATOR. INSIDE IT CAN BE CONVERTED TO ACTIVE FORM AND TRAPPED. WHEN EXCITED WITH A FREQUENCY OF LIGHT, IT EMITS ANOTHER FREQUENCY. FLUORSECENCE IS PROPORTIONAL TO PH. CELL EXPOSED TO PROTON IONOPHORE MAKING THE MEMBRANE PERMEABLE TO H+. SO PH INSIDE = OUTSIDE. PH OF IONOPHORE BATH = IC PH

Question 5

HOW DOES THE CELL CONTROL IC PH

Answer 5

1. BUFFERING
2. ACID EXTRUSION
3. ACID LOADING

Question 6

WHAT IS A BUFFER

Answer 6

ANY SYSTEM THAT MODERATES THE EFFECTS OF AN ACID/ALKALI LOAD BY CONSUMING/RELEASING PROTONS THEREBY MINIMISING THE PH CHANGE TO PROTECT THE CELL.

Question 7

WHAT IS BUFFERING POWER

Answer 7

THE AMOUNT OF STRONG BASE/ACID THAT MUST BE ADDED TO A SOLN IN ORDER TO CHANGE THE PH BY A GIVEN AMOUNT

Question 8

WHAT HAPPENS IF THE PH INCREASES

Answer 8

COOH DONATES A PROTON = COO- + H+ THEREBY INCREASING THE PROTON CONC AND SO DECREASING THE PH

Question 9

WHAT HAPPENS IF THE PH DECREASES

Answer 9

NH2 CONSUMES A PROTON = NH3+ THEREBY DECREASING THE PROTON CONC AND SO INCREASING THE PH

Question 10

WHAT OCCURS IN ACID EXTRUSION

Answer 10

THE NA/H EXCHANGER MOVES NA INTO THE CELL AND H OUT OF THE CELL
RELIES ON THE GRADIENT SET UP BY NA/K ATPASE

Question 11

WHAT ARE THE CHARACTERISTICS OF THE NA/H EXCHANGER

Answer 11

1. HAS A SET POINT - EXCHANGER IS INACTIVE AT ALKALINE PH

2. ALLOSTERIC MODIFICATION - H+ BINDS TO INCREASE THE ACTIVITY OF THE PROTEIN

Question 12

WHAT IS AN EXAMPLE OF AN NA/H EXCHANGER

Answer 12

NHE1

Question 13

WHAT INHIBITS NHE1

Answer 13

LOW CONC OF AMILORIDE

EIPA

Question 14

WHAT OCCURS IN ACID LOADING

Answer 14

CL/HCO3 EXCHANGER MOVES CL INTO THE CELL AND HCO3 OUT OF THE CELL

Question 15

HOW DOES HCO3 MOVED OUT OF THE CELL ALLOW ACID LOADING

Answer 15

H2O+CO2=H2CO3=HCO3+H+

BY PUSHING HCO3 OUT OF THE CELL YOU ARE CAUSING MORE DISSOCIATION OF H2CO3 INTO HCO3 AND H+ THEREBY INCREASING H+

Question 16

WHAT IS AN EXAMPLE OF AN ACID LOADER

Answer 16

AE FAMILY
HAS 4 SUBTYPES
AE1 MAINLY IN RED BLOOD CELLS AND IS RESPONSIBLE FOR CL-/HAMBURGER SHIFT

Question 17

WHAT INHIBITS AE FAMILY

Answer 17

STILBENE DERIVATIVE DIDS

Question 18

WHAT CAUSES THE RESTING INTRACELLULAR PH

Answer 18

WHEN RATE OF ACID LOADING = ACID EXTRUSION