Page 154 - phytochemistry general program

number is an accurate, simple but tedious procedure. A simple, rapid and effective
technique is to measure total cell mass as packed cell volume (PCV).

Growth curve of suspension culture relating the fresh and dry .1
.2
weight versus time in days. .3

The growth curve of most cultures can be divided into five stages as follows: .4

Lag phase:

During this stage the rate of growth is slow due to the adaptation of the cells to the
new environments. There is no cell division but slow cell growth.

The exponential phase:

There is a start of gradual increase in cell number occurs. It is the stage of
beginning cell division.

The linear growth phase (log phase):

There is marked increase in cell number, characteristic increase in the rate of cell
division, obvious cell growth, increase in protein synthesis, increase in RNA
synthesis. Increase in the level of dehydrogenases enzymes and overall increase

in the biomass. This is the stage of active primary metabolism.

Progressive deceleration phase (diminishing growth phase):

There is gradual decline in rate of cell division due to gradual decrease in the
nutrients and exhaustion of most of essential components of the nutrient medium.

Subculturing into fresh medium should be done starting from stage 4

5- Stationary phase: The cells have already been specialized and differentiated in
this stage. All possible levels of cytodifferentiation can be identified at this phase.

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