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.