I had generated the list below to help you prepare and to th

I had generated the list below to help you prepare and to think about the \"how\" and \'why\" of what we did. This list of questions is not sufficient alone as preparation but will get you started. Lab Safety and SOPs. There will be safety/SOP questions on the exam. Describe the procedure used for a correct aseptic transfer. Provide a rationale for each step that prevents contamination. Define contaminant. Know the dyes/chemicals used in all staining procedures. What is the function/purpose of each chemical/reagent? Microscopy - know all parts and functions; magnification, resolution, contrast Acid-fast staining - what docs a positive AFB result indicate? AFB negative? What is the rationale for the acid-fast staining technique? What is the rationale for the Gram staining technique? A correctly prepared Gram stain provides information about three traits of a bacterium. What are they? What are the correct terms used to describe bacterial shapes? What are the correct terms used to describe bacterial arrangements? What is the difference between an agar slant and a semi-solid agar deep? What is the purpose of a semi-solid agar deep? What instrument is used to inoculate a semi-solid agar deep? What instrument is used for almost all other inoculations in an introductory microbiology lab? Why is the age of a culture important when Gram staining? If you have bacterial cells that are Gram positive but the culture is old what will be the Gram reaction? Why? What conditions must be met for autoclaving? Why is it critical to properly label all cultures correctly in a microbiology lab? What are the required elements to properly label a culture? Describe features of the all of the organisms we have used in the lab. Is it possible to identify a microbe by microscopy? By colony morphology? Explain. Is it possible to speciate by microscopy alone? Explain. A mixed broth culture is provided. How could you best determine how many different types of microorganisms are in the broth culture? A pure culture is provided. Gram stain results reveal a Gram-negative microorganism but the arrangement and morphology are in question. The student observes very tiny bacilli and what appear to be cocci. Since this is a pure culture, how would you interpret the morphology? Explain.

Solution

1. Not relevant.

2. Aseptic technique is used for transfer of culture. This technique helps in microbe free transfer of culture.

Steps and their significance:

1. Flaming of the loop : the loop is sterilized by holding it in the flame of the Bunsen burner which kills all the microbes and thus sterilizes the loop.

2. After the loop has become red hot, it is allowed to cool before picking up the cultured microorganisms.

3. Flaming the culture tube: the end of the tube is hold on the flame of the Bunsen burner which results in production of convection current which inhibits the airborne microbes to enter the tube.

4. The culture is transferred in the agar slant very gently.