Lab 3 1. How are microscope slides handled if you do not keep them to review? Microscope slides that you do not wish to keep should be placed in the red, sharps biohaxard container located at the front of the laboratory. 2. For each of the following, list the shape of the bacteria and the grouping of cells that you would expect to see in a stained slide from a broth culture of: <a href="/keyword/bacillus-subtilis/" >bacillus subtilis</a> , Streptococcus mutans. In a stained slide from a broth culture, the shape of <a href="/keyword/bacillus-subtilis/" >bacillus subtilis</a> is rod and Streptococcus mutans is a long, fragile chain. 3. What is the difference in one of the first steps in the preparation of a slide of organisms made from a culture growing on nutrient agar as compared to a culture growing in nutrient broth? The difference in one of the first steps in the preparation of a slide of organisms made from a culture growing in nutrient agar as compared to a culture growing in nutrient broth is the use of water on the slide with organisms made from a culture growing on nutrient agar. When using a smear from broth, use broth only on the slide. Broth cultures are relatively dilute, no additional water is added. 4. Which very important step is not shown in Fig. 4.3? Why is that step so important? The very important step that is left out of figure 4.3 is after placing the bacterial culture on the slide, heat the loop again. It is important to burn off the remaining organisms to avoid contaminating the lab bench. 5. Which organism that is studied in this lab. possesses a capsule ? Describe the appearance of the capsule when these organisms are stained in this lab. Why aren't the bacteria washed off after staining with crystal violet ? 6. What is the purpose of heating a slide that contains organisms that you will stain after the preparation of organisms has been air-dried? Why is it important to dry a slide that has been stained by blotting, not by rubbing ? Heating the slide that contains organisms causes the cells to adhere to the glass so they will not wash off in the staining process. It is important to blot the slide because rubbing will cause the organisms to be removed from the slide. 7. List three characteristics that are used to compare colonies that have grown on agar plates. Each colony grew initially from how many organisms ? 8.How is the microscope treated before it is returned to its cabinet: refer to the lenses, the cord and the stage. Before the microscope is returned to its cabinet, the lenses must be cleaned, the cord must be wrapped around the body and the objective should be on 4x 9. The microscope has a coarse adjustment knob and a fine adjustment knob that each change the distance of the objective lens from the stage: which of these should be used with the following objectives: 4x (scanning), 10x (low power), 40x (high power), 100x (oil immersion)? 4x: Both 1Ox: Both 4Ox: Fine 1OOx: Fine 10. How long is an organism that is 2 ocular units under the 40X objective ? How long is an organism that is 3 ocular units under the 100x objective ? What is the total magnification when each of these objective lenses is used ? An organism that is 2 ocular units under the 4Ox objective is 5Omm long, with a total magnification of 4O. An organism that is 3 ocular units under the 1OOx is 3Omm long, with a total magnification of 1,OOO.