EXP :2.1 OCULAR MICROMETER
INTRODUCTION
Ocular micrometer is used in order to measure and compare
the size of prokaryotic and eukaryotic microorganisms. Microorganisms are
measured with an ocular micrometer which is inserted into the one of the
microscope eyepiece. The micrometer, which serves as scale or rule, is flat
circle of glass upon which are etched equally spaced divisions. This is not
calibrated, and mat be used at several magnifications. When placed in the
eyepiece, the line superimposed certain distance markers on the microscope
field. The actual distance 10µm apart etched. By determining how
many units of the ocular micrometer superimposed a known distance on stage
micrometer, you can calculate the exact distance each ocular division measures
on the microscopic field. When you change objectives you must recalibrate the
system. After calibration of the ocular micrometer, the stage micrometer is
replaced with a slide containing microorganisms. The dimensions of the cells
may then be determined.
OBEJCTIVE
To measure and count cell using a microscope
RESULT
1) Lactobacillus
 |
400x magnification |
 |
1000x magnification |
2) Yeast
 |
1000x magnication |
 |
400x magnification |
DISCUSSION
From this experiment we can determined that yeast has bigger
size compared to lactobacillus because yeast is the example of the eukaryotic organism while lactobacillus is example of prokaryotic
organism.
We observed
both organism using 400x magnification and 1000x magnification(immersion oil)
under the microscope due to it tiny structure.
In the first experiment we are using ocular micrometer to measure and compare the
size of prokaryotic and eukaryotic microorganism. By using the lowest power
objective, focus the microscope until the image on the stage micrometer is
observed superimposed on the eyepiece scale and then calibrate :
400x magnification
|
1000x magnification
|
|||
calibrate
|
Stage micrometer
|
Ocular division
|
Stage micrometer
|
Ocular divison
|
0.03 mm
|
38 division
|
0.09 mm
|
96 division
|
|
7.9x10⁻⁴ mm
|
1 division
|
9.38x10⁻⁴ mm
|
1 division
|
|
0.79 µm
|
1 division
|
0.94 µm
|
1 division
|
|
Size of microorganism : 2 division 5 division
YEAST :
400x magnification
4 division x
0.79 µm
=3.16 µm
1000x magnification
7 division x
0.94 µm
= 6.58 µm
LACTOBACILLUS :
400x magnification
2 division x
0.79 µm
=1.58 µm
1000x magnification
5 division x
0.94 µm
=4.7 µm
Eukaryotic microorganisms are more complex and can be
multicellular or single cell. Prokaryotic microorganism are single cell. Usually
prokaryotes organisms has smaller size compared to eukaryotes because it
lacking in some organelles such as nucleus, cell membrane, endoplasmic
reticulum and chloroplast.
We also able to measure the size of microorganism by using
ocular micrometer and then calibrate it.
REFRENCE
Pearson International edition Biology 8th Edition, Campbell. Reece
EXP : 2.2 NEUBAUER CHAMBER
INTRODUCTION
Neubauer chambers are more convenient for counting microbes.
The Neubauer is heavy glass slide with two counting areas separated by a
H-shaped (figure below). A special coverslip is placed over the counting areas
and sits a precise distance above them.
OBJECTIVE
To counting microbes by using Neubauer chamber
RESULT
YEAST:
 |
| 1000x magnification |
DISSCUSION
For the second experiment we use Neubauer chamber for counting microbes. There are some
step of sterilization step we need to apply for this experiment which is we use
flame sterilization to eliminate potential contaminants from exposed opening of
the media bottle containing yeast during transfers. We also use sterile Pasteur
pipette. All this to prevent us from infected and spread of microorganism.
The chambers contain many grids that producing 9 major large
square. So for the calculation we only used middle large squares . Inside the
middle large square there are 16 smaller squares. Then randomly choose 10 out
of 16 smaller squares and calculate the
number of yeast cells in each of the squares and the cell concentration :
56 ÷ 10 = 5.6
= 6
Volume = 0.05 x 0.05 x 0.01 mm
= 2.5 x 10⁻⁵
mm
= 2.5 x 10⁻⁷
ml
6 cells in 16 squares
1 square = 6 ÷16
= 0.375
cells in 2.5 x 10⁻⁷ ml
1ml = 0.375 ÷ 2.5 x 10⁻⁷
= 1500000 cells/ml
CONCLUSION
As a conclusion, we can count number of cell in colony and the cell concentration using Neubaeur chamber. sterilization process also applied in this experiment.
REFRENCE
Pearson International edition Biology 8th Edition, Campbell. Reece
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