Is life one and undivided ? -Is cellular division common to all living beings ? -Do divisions proceed in the same way?

Is cellular division common to all living beings ?

It is thought that there is a division of cells in all living beings responsible the unity of life : For that we have counted the number of animal, vegetable and bacterial cells there are before and after setting them in a culture.

Material and methods -optical Microscope and the cell of Malassez allows us to observe unicellular animal cells: vegetable yeasts and cells - Spectrophotometer and absorbance (bacterial cells too small to be seen with the optical microscope=>indirect technical use) -MTT colorimetry test on the plate reader and (use for pluricellular animal cells: lymphocytes)

Optical microscope and counting of the cells on a Malassez slide

Preparation of the nutrient necessary to yeast Starch is the nutrient necessary to the development of yeast. We want to know what the concentration is for an optimal developement. 1/10 Dilution

Culture of yeasts Incubation of yeast in the previous tubes of culture The tubes are then left in an incubator for 24 Hours

Incubator The incubator makes it possible to maintain the cells moving at the right temperature needed for their survival

Results water+yeast Without starch water+yeast Starch 0,0001g/ml water+yeast Starch 0,001g/ml water+yeast starch 0,01g/ml A t 0 (en cell/mL) 6,00E+073,10E+073,30E+073,60E+07 At 24 (en cell/mL) 2,10E+081,20E+081,7E+083,00E+08 Cell multiplication factor The richer the culture medium is, the higher is the multiplication of cells

Bacteria 1)Comparison of the growth of bacteria in rich or poor culture medium 2)Analysis with a spectrophotometer 3)Absorbance 60 times higher in a rich culture medium Conclusion: need for a culture medium rich in nutrients is required.

The spectrophotometer and absorbance  The absorbance of the solution is measured with a laser.  This absorbance is proportional to the cell concentration of the sample

Analysis of animal cells multiplication using colorimetric test Principle : Study of 2 culture mediums, one rich in nutrients in presence of FCS (fœtal calf serum) and one poor in nutrients. Colorimetric test:Test based on the activity of the protein MTT: coloration by MTT increases with cell concentration. 1/Wavelenght 620nm. The absorbance is proportional to the cell concentration 2/Tracing of the calibration line 3/Measurement of the absorbance of the different cell culture concentrations from the calibration line. Colorimetric test example Calibriing well 6 wells containing the rich medium 6 wells containing the poor medium

Animal cells : colorimetric test

The animal cells Sample 1 Sample 2 Sample 3Average Standart Deviation + FCS* FCS FCS FCS Foetal Calf Serum The number of cells decreases in poor culture medium

Conclusion 1/Presence of a cellular division in all living beings 2/Division in all living beings requires nutrients