INTRODUCTION
1.1OCULAR MICROMETER.
An ocular micrometer is a glass disk that fits in a microscope eyepiece that has a ruled scale, which is used to measure the size of magnified objects. The physical length of the marks on the scale depend on the degree of magnification.
 |
| figure 1 |
Ocular micrometer is use in order to measure and compare the size of prokaryotic and eukaryotic microorganism. A microscope can be used not only to see very small things but also to measure them. Things seen in microscopes are so small that centimeters or even millimeters are too big. As a result, micrometers (or microns) are used. A micrometer, also written µm, is one thousandth of a millimeter - it's 10-6m.
For this, a micrometer eyepiece is used in place of the standard eyepiece of the microscope. This has a series of numbered lines inside of it which make it look like a ruler
We can calculate the exact distance each ocular division measures on the microscopic field by determining how many units of the ocular micrometer superimpose a known distance on the stage micrometer.We must recalibrate the system when we change objectives.The stage micrometer is replaced with a slide containing microoraganism after calibration of the ocular micrometer then the dimension of cells may be determine.
1.2NEUBAUER CHAMBER
It is more convenient to counting microbes by using Neubauer Chamber.
 |
| figure 2 |
Figure 2 show the picture of Neubauer chamber. The Neubauer counting chamber is used to count cells in a biological fluid by observing through microscope a calibrated grid of which the exact dimensions are known.
A simple calculation allows the number of cells per ml or another volume unit to be determined.
A simple calculation allows the number of cells per ml or another volume unit to be determined.
RESULTS
2.1 OCULAR MICROMETER
1) 40 x magnification
10 eyepiece divisions = 15 stage divisions
1 eyepiece division = 15/10
= 1.5 µm
10 eyepiece divisions = 11 stage divisions
1 eyepiece division = 11/10
= 1.1 µm
11 eyepiece divisions = 40 stage divisions
1 eyepiece division = 40/10
= 3.6 µm
2.2 RESULT (NEUBAUER CHAMBER)
1mm
a | b | ||
e | |||
c | d |
1mm
1 small box = 1 mm\ 4
=0.25 mm
Average of cell number ,H = a + b + c + d + e / 5
= 2 + 4 + 3 + 2 + 2/ 5
= 2.6 cells
Volume of one small box = area x depth
= 0.25 mm x 0.25 mm x 0.1 mm
= 6.25 x 10 -⁶ mL
Concentration of cell = average of cell,H / volume of one small box
= 2.6 cells / 6.25 x 10 -⁶ mL
= 4I6000 cells/ mL
DISCUSSION:
Ocular Micrometer
The advantages of using ocular micrometer is it can be used to measure the size of various microbes in terms of length, breadth, diameter. Some precautions step that need to be taken into account is always repeat the procedures to abotain the average value. Make sure that the image magnified has been focused correctly. If the image is blur, the measured lenght will not be acurate.
Neubauer Chamber
From the experiment that have been conducted, counting yeast cells with Neubauer Chamber is done easily. We are using the methods of counting the cells in specific area. From this method, the average number of cell is obtained. According to refrences, this method has quite high margin of error in obtaining the actual number of cell compare to other chambers. The major advantage of the Neubauer chamber is cheap.
Some of the low-margin error chamber such as Makler chamber,Horwells chamber and many more. It is important to use low-margin error chamber sinceit provides higt accuracy for the result obtained.
In order to reduce the error margin using Neubauer chamber, the average of yeasts contained in several groups of squares can be calculated so that we can obtain the best value for the number of yeast cell.
There are several of the precaution steps involving Neubauer chamber.Firstly, is to avoid contamination during the transfer of the diluted yeast call culture, so that we will only count yeast cell. This can be done by using clean and steriled Pasteur pipette. Next, is to magnify into proper and suitable magnification,so that we can count the cell in the saperate grid squares correctly.
By comparing the result with refrences, the cell count in 1 square is compared to the refrences with average of 14 cell per 1 middle large square.
70% of ethanol is used to clean the Neubauer and cover slip because to avoid contamination, and it is easy and fast to evaporate. The cells is allowed to settle for 1 minute in order for the yeast cell to be well spread across the entire chamber.
Refrences of counting yeast cell: Average 14 cell per 25 small squares
CONCLUSION:
As the conclusion we able to learn measurement and counting of cells using microscope .
2.1 Oscular Micrometer
Oscular micrometer is use to measure the size of cells by using the different magnification when it is inserted into one of the microscope eyepieces.The stages of division are differ at different magnification. For 40x magnification the size is 1.5µm,at 100x magnification 1.1µm and for 400x magnification the size is 3.6µm.
2.2 Neubauer Chamber
Neubauer chamber is use to counting microbes. We used only middle large square which 16 smaller square. The average of the cell is 2.6 cells,the volume of one small box of the cells is 6.25 x 10 -⁶ mL and the concentration of cell is 4I6000 cells/ mL.
REFERENCES:
No comments:
Post a Comment