NAME SURNAME :ahmet mehmeh
STUDENT ID :
DEPARTMENT : MOLECULAR BIOLOGY AND GENETİCS DATE OF EXPERIMENT: 02.03.2011
In this experiment,the cell growth of yeast is measured by using spectrophotometer and hemocytometer.We learnt how specthophotometer and hemocytometer use and also we learnt qualifications of hemocytometer and spectrophotometer.Serial dilution was used for this experiment and it was very important.Because of the serial dilution,we measured the number of yeast cells. The graph of growth curve was drawn and bacterial life cycle was understood with the graph.The purpose of the experiment was to calculate and draw bacterial growth curve. INTRODUCTION
In this experiment,we learnt cell growth.Cell growth means increase in the quantity of cellular constituents.Cells in culture double its number because they produce two daughter cells by dividing.Generation time is the constant time when cells in the culture double their number.This kind of growth depends on some requirements such as type of the cell and environment.Two different parameters can be used to calculate growth for unicellular organisms such as bacteria and yeast:changes in cell mass and cell number.There are some different ways for measuring the cell growth with cell mass.Physical measurement:dry weigth,wet weigth or volume after centrifuge and: Chemical measurement chemical components such as N,total protein and DNA and Chemical activity:rate of , CO2 production or consumption; Turbidity (spectrophotometric) measurement: based on turbidity and measure both dead and alive cells.Spectrophotometer can measure intensity of the light source wavelength.Spectrophotometers are important in terms of spectral bandwith and linear range of absorption or reflectance measurement.Spectrophotometers are used for physics,material science,chemistry,biochemistry and molecular biology experiments.Why must spectrophotometerbe set to a wavelength of 600nm?Because biological chemicals absorb light int the UV-Visible range in terms of resonance of bonds.600nm is used because the cells absorb at this wavelength. There are some different ways also for calculating cell growth with cell number which counting chamber,viable cell testand the cfu. Counting chamber(hemocytometer):is used to learn number of cells and concentration of cells in a certain volume of a suspension.On the other hand,the cell viability and cell type can not be measured for using hemocytometer.If you want to use hemocytometer,in first place you should clean it and coverslip.After that,you drop of cell suspension and then coverslip is placed on the sample.The suspension should be completed the counting grid which should be observed under microscope.The concentration of suspension should be dilute to obtain different form of cells.Dillution can provide to count cells easily.In number of squares and the total number count and then record.The product of volume and the number of squares we count gives the total volume and the we should divide the number we count to the total volume.Multiply the dilution factor is very important in this experiment.
Plate counts: consist of diluting sample until the bacteria are dilute enough o count accurate. After diluting the final plates should have 30 to 300 colonies. Each colony that can be counted is called colony forming unit (cfu). The numbers of colonies give the number of bacteria that can grow. A wide serious of dilutions is normally plated because the exact number of bacteria is unknown.
10-1 10-2 10-3 10-4 10-5 10-6 Viable Cell Test:is used to determine whether the cells are living or not in the cell sample by using dyes which indicate the living and death ones. Starter flask contains carbon source ,TAG,aminoacid and base in order to support proliferation of optimum number of...
References: * file:///C:/Documents%20and%20Settings/Admin/Desktop/Spectrophotometry.htm
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