Biotech 2nd Edition Sample Ch. 4 Biotechnology Sample Ch. 4 - Page 14

Thinking Like a Biotechnician 1. After making several batches of sterile LB broth, you see pieces of dust in the broth. Is the broth suitable to use? How could the dust have entered the bottles? 2. Why is it not advisable to heat or sterilize media longer than necessary? 3. Additional compounds can be added to agar before sterilization (or sometimes after). An example of this is “milk agar,” in which 2% nonfat powdered milk is added to the agar base. Lactose-digesting bacteria like to grow on milk agar. How many grams of nonfat powdered milk should be added to the 125 mL of LB agar to end up with 2% milk LB agar? Show your calculations. 4. Growing mammalian, fungal, and bacterial cells in or on sterile, prepared media is critical for their study. Each type has specific requirements for growth. Access the following Web site to find information that allows you to compare and contrast the ingredients required by E. coli bacteria cells versus human cells in culture: Record your analysis in your notebook. How many more ingredients are necessary for human cell culture? Explain why mammalian cells, such as human cells, have so many more required ingredients in their growth media. DNA Isolation and Analysis 79