Question

10 Smear Preparation A. Short-Answer Questions 1. How does smear preparation of cells from a liquid me medium? ar preparation of cells from a liquid medium differ from preparation of cells from a solid 2. Why is it important to limit the quantity of cells used to prepare a smear? 3. Describe the potential consequences of making a smear that is too thick. 4. For preparation of a smear on a slide, what is the purpose of heat fixation? What problems can arise when the slide is heated in a flame?

Answer 1

Q.1. Answer-

The smear preparation from liquid medium starts with resuspending culture by tapping the tube with fingure then one or two loopful of culture applied on center of slide and spreaded evenly over slide by sterile inoculating loop.

The smear preparation from organisms grown on solid medium started with placing 1-2 drops of water on slide and then cells transferred from solid medium to water drop by sterile loop. Then with needle cells are mixed in water to avoid clumping of cells.

Q.2. Answer-

Excess amount of cells in smear causes staining artifacts stain is can not be washed away completely destaining agents or water and cells can not be seen separately under microscope.

Q.3. Answer-

Thick smear diminishes light passing through layer of bacterial smear so that morphology of single cell is difficult to visualize .

Q.4. Answer-

Heat fixing enhances adherence of bacterial cells to slide so that cells will not washed of during staining procedures. Heat also denatures bacterial enzymes which prevents digestion of cell parts so that intact cell can be seen.

When slide is heated in flame then cell size and shape gets distorted. Motile organisms can not be identified as organisms gets killed by heat.