EFFECT OF pH,CARBON DIOXIDE ,OXYGEN AND TEMPERATURE ON CELL GROWTH

pH : MOST CELL GROW WELL AT pH 7.4 pH FOR CELL GROWTH VARIES RELATIVELY AMONG DIFFERENT CELL STRAINS OPTIMUM PH CAN BE CHECKED PHENOL RED IS USED AS A INDICATOR

CO2 AND BICARBONATE: DIFFICULT TO DETERMINE THE DIRECT EFFECT OF CO2 CO2 IN THE GAS PHASE DISSOLVES IN THE MEDIUM ,ESTABLISHES EQUILIBRUIM WITH HCO3- IONS AND LOWERS THE pH . DIFFICULT TO DETERMINE THE DIRECT EFFECT OF CO2 THE ATMOSPERIC CO2 TENSION WILL DIRECTLY REGULATE THE CONC. OF DISSOLVED CO2,as a function of temperature . This regulation produces:

THE NET RESULT IS INCREASE IN ATMOSPHERIC CO2 IS TO DEPRESS THE ph SO THE EFFECT OF ELEVATED CO2 TENSION IS NUETRaliZED BY INCREASING THE BIOCARBONATE CONC. NaHCO3  Na+ + HCO3- The INCREASED CONC. OF HCO3- PUSHES THE EQUATION TO THE LEFT UNTIL pH BECOMES 7.4 MANY MEDIA ARE MADE UP OF ACID SOLN MAY HAVE BUFFER ,IT IS DIFFICULT TO PREDICT THE AMOUNT OF BIOCARBONATE TO BE USED.

ASSUMPTION OF USE OF good’s buffer INSTEAD of co2 IS UNTRUE THE INCLUSION OF PYRUVATE IN THE MEDUIM ENABLES CELLS TO INCREASE ENDOGENEOUS PRODUCTION OF CO2. CULTURES IN OPEN VESSELS NEED TO BE INCUBATED IN CO2 INCUBATORS IF CELLS ARE HIGH ACID PRODUCERS THEN NEED NOT TO BE SUPPLIED WITH CO2 IN GAS PHASE.

OXYGEN: CULTURE CELLS RELY ON GLYCOLYSIS,A HIGH PORTION OF WHICH TRANSFORMRD CELLS, MAY BE ANAEROBIC. RELY ON DISSOLVED O2 ,CAN BE TOXIC DUE TO ELEVATION IN LEVEL OF FREE RADICALS. CULTURES MAY VARY O2 REQUIREMENTS O2 TENSION MAY LIKELY TO BE MORE CRITICAL IN SERUM FREE MEDIA DEPTH OF THE CULTURE MEDUIM CAN INFLUENCE THE RATE OF O2 DIFFUSIUON TO THE CELLS.

TEMPERATURE: OPTIMUM TEMP FOR CELL CULTURE IS DEPENDENT ON : THE BODY TEMP OF THE ANIMAL FROM WHICH THE CELLS WERE OBTAIN. ANY ANATOMIC VARIATION IN TEMPRATURE. THE INCORPORATION OF A SAFETY FACTOR TO ALLOW FOR MINOR ERROR IN REGULATING THE INCUBATOR.

CULTURED MAMMALIAN CELLS WILL TOLERATE CONSIDRATION DROPS IN TEMPRATURE. THE SPATIAL DISTRIBUTION OF TEMPERATURE WITHIN THE INCULBATOR SHOULD BE UNIFORM.

VISCOSITY VISCOSITY HAS A LITTLE EFFECT ON CELL GROWTH. IT BECOMES IMPORTANT IN SUSPENSION CELLS. PLAYES KEY ROLL WHEN THE SUSPENSION CULTURE IS STIRRED.

SURFACE TENSION AND FOAMING EFFECTS OF FOAMING NOT CLEARLY DEFINED. LIMITS GASEOUS DIFFUSION OF A FILM FROM A FOAM. ANTI FOAM AGENTS ARE ADDED.

OSMOLALITY MOST CULTURED CELLS HAVE FAIRLY WIDE TOLERANCE OF OSMOTIC PRESSURE. USUALLY MEASURED BY DEPRESSION OF THE FREEZING POINT AND ELEVATION OF VAPOUR PRESSURE OF THE MEDIUM. MEASUREMENT OF OSMOLALITY IS A USEFUL QUALITY CONTROL STEP IF YOU ARE MAKING UP THE MEDIUM YOUR SELF.