Lab 1- Nur'Ain binti Zulkefli-111399

1.2 EXAMINATION OF CELLS

INTRODUCTION

Because of their extreme minutenesss, bacteria are not generally studied with the low-power or high power-power dry objectives. Instead they are stained and observed with the oil immersion objective.

The wet mount methods enables you to study the sizes and shapes of living microorganism (drying or staining microorganism distort them). It also enables you to determine if cells are motile. The wet mount method is quick and easy , and does not require special equipment.

OBJECTIVE

• Tp provide an experience in the use of microscope.
• To illustrate the diversity of cells and microorganism.

RESULT

Typical bacilus 

40x magnification

Typical bacilius

10x magnification

Typical bacilius

400x magnifications

Lactobacilius fermentum

40x magnfication

Lactobacilius fermentum

100x magnification

Sacchamnyces arerisiae (yeast)

400x magnification

Sacchamnyces arerisiae (yeast) 

1000x magnification

DISCUSSION

1.  Stained cells.

           The result of Typical bacilius shows that it is a Gram-positive bacteria.Gram-positive bacteria has thick cell wall which made up of peptidoglycan. This will traps crystal violet in the cytoplasm. Besides, it is a rod shape. Alcohol does not remove the crystal violet, which masks the added red safranin dye. Most bacterial cell has a network of modified-sugar polymers cross-linked by short polypeptides. Hence, we observe the cell using different types of magnification. (4x,10x and 40x).

     2. The wet mount.

          The wet mount experiment helps to study the sizes and shapes of microorganism.During this experiment, the specimen suspended in a drop of liquid located between  slide and cover glass. Besides, it is quick preparation and easy to observe living organism. To observe the organism , we use different magnification  which is 4x, 10x and 40x . We also use immersion oil (100x magnification)  and the function of the this oil is to get better resolution and brightness. These characteristics are most critical under higher magnification.

                 We apply aseptic technique in this experiment. First, slowly heat the incoluting wire until its glows orange. Second, cool it before attenting any transfer of material.Third, we heat the mouth of opening bottle. This is to make sure that we are not infected and prevent spread of microorganism.

                   In addition, we also observed Lactobacillus fermentum under 40x and 100x magnification and the result is rod-shape structure.Lactobacillius cannot be seen under 4x and 10x magnification because it is too small. For the yeast also, it cannot be seen under 4x and 10x magnification and can only seen under 40x and 100x magnification. Yeast do not contain chlorophyls. The shape of yeast are cocci or spherical structure. We can see the clearly image using immersion oil at 100x magnification.

CONCLUSION

Gram staining is a method differentiating bacteria species  into two large group which is Gram-positive and Gram-negative.It based on the chemical and physical properties of the cell wall.Primarily, its detects peptidogylcan, which is present in thick layer   Gram-positive bacteria. A Gram-positive results in a purple color while a Gram-negative results in a pink color.
In light microscope, oil immersion is a technique used to increased resolution of microscope.This is achieve by immersing both the objective lens and the specimen in a transparent oil of high refractive index, thereby increasing  numerical aperture of the objective lens.

REFERENCES

http://en.wikipedia.org/wiki/Gram_staining

http://en.wikipedia.org/wiki/Oil_immersion 

Pearson International Biology, 8th Edition, Campbell, Reece