4. Why might a physician perform a Gram stain on a sample from a sick patient before prescribing an antibiotic? 5. What color would protozoa be if they were stained using the Gram stain procedure? What color would human cells be? Why? 6. What chemical charge (positive or negative) do crystal violet and safranin have? How do you know this? 7. Which species of bacteria that you stained has the largest cells? Readings: Textbook pages 71-73 Lab book pages 31-34 Background Questions: 1. Why are capsules difficult to stain? 2. What would a smear of encapsulated bacteria look like if a purple negative stain and a blue direct stain were used? 3. Why are endospores difficult to stain? 4. What would a smear of endospore-producing bacteria look like if stained with a red direct stain only? 5. Why are flagella difficult to stain? 6. Why is a mordant required when staining flagella?