Yeast, Epithelial and Dental plaque
Compare your observations from the four activities of fresh wet mount, direct staining using crystal violet, and indirect staining using both Congo Red and crystal violet.
Wet mount of S. cerevisiae under magnification of X10 and X40, revealed the cells as being independent, with oval shapes. All the cells in wet mount, had same shape appearance, with borders that could not be clearly distinct. However, in wet mount, it was not easy to determine epithelial cells shape. In the direct staining, cells shapes could be determined since cells had a violet color. This made the cells to be visible clearly. When indirect staining was done with Congo dye, cells-background appeared red and no color on the cells. This also enabled clear observation of the cells shape. However, as much as S. cerevisiae cells shape was distinct, epithelial cells had no clear shape distinction. The best result was seen in the crystal violet staining.
Discuss whether you were able to identify specific bacterial morphologies.
Cocci-shaped bacteria were observed in crystal violet staining. However, wet mount did not show any bacterial morphology
Explain the difference between direct and indirect staining.
Direct staining involves the use of basic dyes like safranin, crystal violet and methylene blue that usually have positive ions, to attract bacterial cells with negative ions, to form visible color with the bacterial cells. Indirect staining involves the use of acidic dyes like Nigrosine, Indian ink and Congo red that usually have negative ions, which repel the bacterial cells to form visible color with bacterial cells background, since like charges repel (Sumbali & Mehrotra, 2009, p. 50).
Discuss whether the smears appeared different in each type of staining.
The cells in direct staining were stained violet due to crystal violet, whereas the cells-background were not stained. In indirect staining, cells were not stained, while the cells-background was stained red due to the Congo dye. This therefore made the smears to appear different under these different staining methods.
Explain why the smears did or did not appear different in each type of staining.
Smears appeared different since smears in direct staining absorbed the basic chromophore to give the violet coloration as the smear had negative charged ions, while the smears in indirect staining repelled the acidic chromophores, causing red background coloration as the smear had same ion charge as the Congo red dye.
Explain the similarities and differences between the cells in the plaque and those in the yeast smears.
The similarity was that both yeast and plaque cells had nucleus on their cells. The difference was in morphology, where smear of yeast cell was independent, whereas plaque cells were attached to each other forming a layer. Again, the yeast cells were larger in size compared to the cell size of plaque cells. Another difference was that plaque cells had only cell membrane compared to yeast cells which had both cell membrane and cell wall.
Describe the size and shape of the types of cells that you were able to see in the smear from your mouth.
There was great variation in sizes and shapes of mouth smear. Shapes from mouth smear included polygonal, oval, spindle as well rectangular shape. Cells also seemed to be attached to each other, thus forming a layer. With the observed shapes, this strongly suggest
That these epithelial cells had perfect cells arrangement to enable it perform its protective function for the inner tissues efficiently.
References
Sumbali, G., & Mehrotra, R. S. (2009). Principles of microbiology. New Delhi: Tata McGraw-Hill.
