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

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 1/10 1/10Dilution

Culture of yeastsIncubation 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

Resultswater+yeast

Without starch

water+yeast

Starch 0,0001g/ml

water+yeast

Starch 0,001g/ml

water+yeast starch 0,01g/ml

A t0(en cell/mL)

6,00E+07 3,10E+07 3,30E+07 3,60E+07

At24(en cell/mL)

2,10E+08 1,20E+08 1,7E+08 3,00E+08

Cell multiplication factor

3.5 3.9 5.2 8.3

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 spectrophotometer3) 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 line3/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

y = 535678x - 19893R2 = 0,9691

0,00E+00

1,00E+05

2,00E+05

3,00E+05

4,00E+05

5,00E+05

6,00E+05

0 0,2 0,4 0,6 0,8 1

absorbance

nom

bre

de c

ellu

les

The animal cells  Sample 1  Sample 2   Sample 3 Average

Standart Deviation

+ FCS* 121525 127954 152056 133845 16095

+FCS 153663 45992 149381 116345 60965

-FCS 118311 53493 84028 85277 32427

-FCS 99027 60458 82421 80635 19346

0,E+00

2,E+04

4,E+04

6,E+04

8,E+04

1,E+05

1,E+05

1,E+05

2,E+05

2,E+05

2,E+05

+ FCS +FCS -FCS -FCS

Cel

l num

ber

•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