Yeast Suspension

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  • Topic: Dilution, Serial dilution, Bacteria
  • Pages : 6 (1513 words )
  • Download(s) : 107
  • Published : September 28, 2012
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DCP & CE

Title
The effect of the different dilutions of yeast cell suspension on the number of yeast cells per cm3 that counted using haemocytometer under microscope.

Aim
To investigate the effect of the different dilutions of yeast cell suspension on the number of yeast cells per cm3 that counted using haemocytometer under microscope.

Research Question
Do the different dilutions of yeast cell suspension affect the number of yeast cells per cm3 that counted using haemocytometer under the microscope?

Introduction
“The typical yeast cell is approximately equal in size to a human blood cell”. It is so small and present in such huge number that it is hard to be counted. To verify accurately the number of yeast cells, a haemocytometer need to be used as it is the most suitable for counting microorganisms under the microscope. Haemocytometer has a grid that is etched into the glass. The grid is an arrangement of squares of different sizes that allows for an easy counting of cells. It is also carefully crafted so that the area bounded by the lines is known, and the depth of the chamber is also known. Thus, it is possible to determine the number of cells in a specified volume of fluid.

Hypothesis
As yeast cell suspension become more diluted, the number of yeast cells per cm3 that counted using haemocytometer under the microscope decrease. This is because when more distilled water used, the smaller the ratio of yeast suspension to distilled water become. It means that the less yeast cell suspension will occupy the dilutions per cm3 as the yeast cell suspension get more diluted because the yeast cells had been widely distributed.

Variables
Independent variable : Different dilutions of yeast cell suspension which are one-to-hundred dilution (1/100), one-to-one thousand dilution (1/1000), one-to-ten thousand dilution (1/10,000), one-to-hundred thousand dilution (1/100,000) and one-to-one million dilution (1/1,000,000).

Dependent variable : Number of yeast cells per cm3 that counted using haemocytometer under the microscope.

Controlled variable :
1. Type of yeast cells
* The same type of yeast cells are used to make different dilutions of yeast cell suspension. 2. Volume of distilled water added in each serial dilution * 9 ml of distilled water are used in making every each of dilution of yeast cell suspension. 3. Way of counting the number of yeast cells

* 4 squares are considered in counting the total number of yeast cell for every group.

Apparatus and Materials

Apparatus| Quantity(s)|
10 ml ± 0.1 ml Measuring cylinder| 1(Measuring cylinder is used to measure 1 ml of yeast cell suspension and 9 ml of distilled water)| Test tube| 6(Test tube is labelled as A, B, C, D, E, and F)| Glass rod| 1|

Dropper| 1|
Haemocytometer| 1|
Cover slip| 1|
Capillary tube| 1|
Microscope| 1|
Petri dish| 1|
Hand tally counter| 1|

Materials| Quantity(s)|
1 ml Suspension of yeast cell| 1|
Alcohol| Several drop|
Distilled water| 54 ml(9 ml in Test tube A, 9 ml in Test tube B, 9 ml in Test tube C, 9 ml in Test tube D, 9 ml in Test tube E, 9 ml in Test tube F)| Tissue paper| Several pieces|
Lens tissue| Several pieces|

Procedures

A. Setting up the slide
1. The haemocytometer is cleaned with alcohol and wiped with lens tissue to ensure it is grease-free. 2. A damp tissue is used to moisten the shoulder of the haemocytometer to allow the cover slip to stick on it. 3. The special cover slip is pushed on to the slide and the outside edges of the cover slip is pressed down at the same time until Newton’s rings is seen. B. Loading the haemocytometer

4. The yeast cell suspension is gently shaken and well stirred to ensure the suspension is properly mixed. 5. The end of capillary tube is inserted into the suspension and risen the liquid into the tube. 6. The end of capillary tube is run along the edge...
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