EXAM 1

You have two hours to complete this exam. Please write legibly and concisely. You should be able to answer each of the questions with a few sentences in the space allotted. However, if you have big handwriting, write on the back of the paper. Give as complete an answer as possible that displays your understanding of the subject and the mechanisms that govern it.

1. Dr. White-Ziegler’s research students celebrated her tenure decision, making her cake with an M&M lipid bilayer, licorice fimbriae, and a blue frosting chromosome. They left it in her office overnight so she would see it in the morning, not thinking what might happen (microbiologically) in the meantime! She is thrilled and dives headlong into the cake, munching down a generous portion. Later that morning, she walks into her microbiology class and starts dancing around the room as she discusses cell structure and function. Thinking she is just deliriously happy and on a sugar high, the students initially don’t think too much about it. However, when she starts announcing that eukaryotes are better than prokaryotes, they know something is definitely wrong! She then begins to make a chart on the board “Why eukaryotes are wonderful”. You have had enough! Not being able to contain yourself much longer, you run to the board, erase the crazy statement, and write “The amazingly unique and efficient characteristics of our beloved prokaryotes” Below, fill in this chart with 6 characteristics of prokaryotes, delineating how they differ from eukaryotes. (12 points).

2. Suspecting the cake is the culprit to cause Dr. White-Ziegler to make such crazy statements, the microbiology students use their newly acquired microbiological skills, stick their loops in the cake, and inoculate an agar plate. Name 2 characteristics that they can acquire for use in identification of the bacterium just by streaking the sample on the plate (4 points).

3. Realizing they need more information than this, Jill suggests that they use the brightfield microscopes and staining reagents in the lab to determine more about this bacterium. Name 5 more characteristics they can determine in the laboratory (10 points).

4. Given Dr. White-Ziegler’s research interest and doubting the sterile technique of the students in the research lab, Amy suggests they check if the bacterium is a fimbriated strain that might have gotten in the cake. What do fimbriae do for a prokaryotic organism? Describe a method they could use to visualize these structures. Why does this method need to be used and what is special about this method that allows visualization, making it advantageous over other methods? (8 points)

5. In the midst of looking for fimbriae, they notice that the bacteria have flagella. Allegra notes that when they sampled the cake all of the bacteria were found in the extra sugary frosting (Isn’t that where you would want to be?). Describe the process that would explain why and how all of the bacteria have localized to the frosting (10 points)