Yeast and hymocytometer

Authors Avatar by hnor_nhk (student)

NAME : NUR SAKINAH BINTI ISMAIL

CLASS : M12F

TEACHER`S NAME : PUAN MAZDIYAH BINTI

SUBJECT : BIOLOGY HIGH LEVEL

TITLE : Yeast cells and haemocytometer

AIM : To investigate the effect of  five different dilutions of yeast suspension on the number of cell        

per mm3

RESEARCH QUESTION : How do the five different dilutions of yeast suspension effect the number of

cell per mm3

INTRODUCTION :Yeast are tiny single-celled (unicellular) fungi. The organisms in the Kingdom Fungi   are not capable of making their own food. Fungi, like any other organism, need food for energy. They rely on sugar found in their environment to provide them with this energy so that they can grow and reproduce.

        Yeast, like bacteria grow in or on their food source. They produce and release digestive proteins (enzymes) into their environment where the sugar molecules are found. Complex sugar molecules then break down into monosaccharides that can be absorbed by the yeast and used for food (energy).

        There are many species of yeast, and each has a particular food source. Certain yeast feed on a variety of natural sources of sugar such as fruits, nectar from plants, and molasses from the plant crop called sorghum. Others break down wood and corn stalks. In doing this, a compound called ethanol is produced. This compound can be used in our cars like gasoline. Another species break down sugar from grain into alcohol. Others break down fruits into wine, which is another type of alcohol. Bread recipes rely on yeast to break down sugar in flour.

The haemocytometer or haemocytometer is a device originally designed for the  of . It is now also used to count other types of as well as other microscopic particles.Thehaemocytometer was invented by  and consists of a thick   with a rectangular indentation that creates a chamber. This chamber is engraved with a laser-etched  of perpendicular lines. The device is carefully crafted so that the area bounded by the lines is known, and the depth of the chamber is also known. It is therefore possible to count the number of cells or particles in a specific volume of fluid, and thereby calculate the concentration of cells in the fluid overall.

Haemocytometers are often used to count  corpuscles,  within cells, blood cells in  after performing a , or other cell types in suspension. Anchorage-dependent cells can also be counted if subjected to  prior to counting. Using a special haemocytometer with a depth of 0.02mm smaller particles such as sperm, yeast or bacteria can be counted. Using the ruling described above the volumes are only 1/5 compared to the standard 0.1mm deep chamber. As it is difficult to distinguish between living and dead organisms unless particular stains are used to distinguish viable from non-viable cells this results in a 'total count' of the bacteria.

Join now!

HYPOTHESIS : The more dilute the yeast suspension, the less the density of the number of cells. It is because, the more distilled water is added to the yeast suspension, the number of yeast cell per mm3 of the yeast suspension decreases. The yeast cell become more widely divided because the volume of distilled water had increased. In the concentrated solution, the number of yeast cells per unit volume of water is more than in a diluted suspension where the density of yeast cells is lower due to the smaller ratio of yeast suspension to the distilled water. This is because, ...

This is a preview of the whole essay