Bacterial Cells Dr. Pettit Flashcards
Your interested in studying a Gram - capsulated bacteria and decide to stain it for observation. What staining method would you use?
A) Negative staining
B) Heat required staining
C) mordant staining
D) malachite green
Negative staining for capsules
A lab partner of yours inquires about how to perform a capsule stain, your notes are a mess but you know you have all the steps written down somewhere. Which is the correct order of the staining process?
A) Heat sample for 5 min to drive malachite green into the capsule and then counterstain with safranin
B) Add an acidic dye such as India ink, then stain the cells with some other type of simple stain
C) Add a negatively charged dye such as nigrosine, which will repel from the negatively charged bacteria, then wash and counterstain with calcium dipicolinate
D) heat fix the sample, add trypan blue, counterstain with malachite green and then add a mordant.
B) capsule stains are done with the understanding that the negatively charged bacteria will repel a negatively charged acidic dye thus staining the background. Then a simple stain is done for the cytoplasmic contents of the bacteria such that the white capsule is surrounded by color on both sides.
C) started out correctly, but calcium dipicolinate is the chemical thought to preserve DNA in endospores
A) This is endospore staining
D) just made it up
You want to impress some of your lab buddies by staining a flagellin, but after using tannic acid to thicken the flagella so as to be able to observe it under a light microscope you still don’t see them. Frustrated you decide to troubleshoot your methods. Assuming you did the staining correctly, what likely went wrong?
A) You need an electron microscope
B) you need to use potassium alum not tannic acid
C) your dealing with an endoflagella
D) It’s not possible to stain flagellin
C) endoflagella are inside spirochetes and are not extracellular and subject to these staining methods.
B) potassium alum can also be used for this stain but so can tannic acid
A) a light microscope is used to view these structures
