2.1 Ocular Micrometer
Introduction
Ocular micrometer is use in order to measure and compare size of prokaryotic and eukaryotic microorganisms. Suitable scale for their measurements should be somewhere in the microscope itself.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 depends on the degree of magnification. the ocular micrometer is inserted in the right eyepiece of the microscope. the calibration factor for the ocular micrometer specific for each ocular objective combination because the objectives have different values of magnification. we can used different type of the magnifications to observe the sample. firstly, we need to calibrate ocular micrometer before used it to observe the cells. it is because the ocular micrometer is inserted inside the ocular lens, it will not change size when the objectives are changed. Therefore, each objective lens must be calibrated separately.
ocular micrometer
Objective
To measure and cells using a microscope.
Results
1. Lactobacillus sp.
400x magnification
1000x magnification
2. Yeast
400x magnifications
1000x magnifications
calibration:
400x:
5 x 0.01 = 0.05
0.05/ 20 = 0.0025 mm
1000x:
5 x 0.01 = 0.05mm
0.05/ 47 = 0.0011 mm
1. Lactobacillus sp.
400x magnification :
2 division x 0.0025 mm = 0.005 mm
1000x magnification :
5 division x 0.0011 mm = 0.0055 mm
2. Yeast
400x magnfication :
5 division x 0.0025 mm = 0.0125 mm
1000x magnification :
7 division x 0.0011 mm = 0.0077 mm
Discussion
from our experiment, we need to measure the cells that we observe which are Lactobacillus sp. and Yeast using the ocular micrometer. An ocular micrometer is a small glass disk with thin lines and numbering etched in the glass.
the ocular micrometer
we can used the ocular micrometer to observe the eukaryotes and the prokaryotes cell and measure their length by using this device. first we need to calibrate both the ocular micrometer at the eyepiece and the stage micrometer at the stage so that both of them superimpose to each other. then we can get the actual number for one devision of the micometer. The vertical distance of an object that is in focus. When magnification is increased, less of the object is in focus (depth of field decreases) – but greater detail of the area in focus can be seen. in this experiment we used Lactobacillus sp. the prokaryotes and the yeast as for the eukaryotes.
Prokaryotes are organisms made up of cells that lack a cell nucleus or any membrane-encased organelles. Eukaryotes are organisms made up of cells that possess a membrane-bound nucleus (that holds genetic material) as well as membrane-bound organelles. Genetic material in eukaryotes is contained within a nucleus within the cell and DNA is organized into chromosomes. we used 400x magnification and 1000x magnification to observe both of the cell. then when the measurement is recorded, we calculated the result obtained to get the actual length of the cells.
Conclusion
as the conclusion, we can determined the sizes and the measurement of the cells by using the ocular 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. by using the devices, it can help us to estimate the cells in our experiment. we need to calibrate the ocular micometer placed in our microscop so that we can know the measurement for one division.
Reference
2.2
NEUBAUER CHAMBER
Introduction
The hemocytometer or haemocytometer is a device originally designed for the counting of blood cells. It is now also used to count other types of cells as well as other microscopic particles. The hemocytometer was invented by Louis-Charles Malassez and consists of a thick glass microscope slide with a rectangular indentation that creates a chamber. This chamber is engraved with a laser-etched grid 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. For microbiology, cell culture, and many applications that require use of suspensions of cells it is necessary to determine cell concentration. One can often determine cell density of a suspension spectrophotometrically, however that form of determination does not allow an assessment of cell viability, nor can one distinguish cell types. A device used for determining the number of cells per unit volume of a suspension is called a counting chamber. The most widely used type of chamber is called a hemocytometer, since it was originally designed for performing blood cell counts.
Objective
1.
To
count cells using microscope.
Results
400 x magnification
sum of the cell 10 box = 642
average = 642/10 = 64.2
volume box (16 box) = 0.2 mm x 0.2 mmx 0.1 mm
= 4 x 10^-3 mm
= 4 x 10^-6 cm^3
64.2 cell in 4 x 10 ^-6 ml
1 ml = 642/ 4 x 10 ^-6 = 1.61 x 10^8 cell/ml
Discussion
the method for using Neubauer chamber are we must ensure that the special coverslip provided with the counting chamber (thicker than standard coverslips and with a certified flattness) is properly positioned on the surface of the counting chamber. the cell suspension is applied to the edge of the coverslip to be sucked into the void by capillary action which completely fills the chamber with the sample. Looking at the chamber through a microscope, the number of cells in the chamber can be determined by counting. Different kinds of cells can be counted separately as long as they are visually distinguishable. The number of cells in the chamber is used to calculate the concentration or density of the cells in the mixture the sample comes from. It is the number of cells in the chamber divided by the chamber's volume (the chamber's volume is known from the start). some of the aseptic technique is applied to avoid contamination to occur.
Conclusion
Neubauer chamber is a tecnique to observe and calculate the cells observed in a specific way. at the last of the experiment, we get the result and achieved our objective. some of the safety measures must be taken to avoid contamination and error in our result.
Reference
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