. How many grams of each component would you need to weigh to prepare one liter of Terrific Broth? Show your work for credit.
The Correct Answer and Explanation is:
Answer:
To prepare 1 liter of Terrific Broth:
- Tryptone: 1.2% (w/v) means 1.2 grams per 100 mL
- Yeast extract: 2.4% (w/v) means 2.4 grams per 100 mL
Since the target volume is 1 liter (1000 mL), calculate the required mass for each component:
For tryptone: 1.2 g/100 mL×1000 mL=12 g1.2 \, \text{g} / 100 \, \text{mL} \times 1000 \, \text{mL} = 12 \, \text{g}1.2g/100mL×1000mL=12g
For yeast extract: 2.4 g/100 mL×1000 mL=24 g2.4 \, \text{g} / 100 \, \text{mL} \times 1000 \, \text{mL} = 24 \, \text{g}2.4g/100mL×1000mL=24g
Thus:
- Weigh out 12 grams of tryptone.
- Weigh out 24 grams of yeast extract.
- Dissolve both in enough distilled water to bring the final volume to 1 liter.
Explanation (about 300 words):
Terrific Broth (TB) is a rich bacterial growth medium commonly used for culturing Escherichia coli and other bacteria, especially when high-density growth is desired. Like many growth media, its formulation is often described in terms of percent weight/volume (% w/v), which indicates the number of grams of solute present in every 100 milliliters of solution.
The composition provided includes 1.2% (w/v) tryptone and 2.4% (w/v) yeast extract. The % w/v notation directly translates to grams per 100 milliliters. Therefore, 1.2% w/v tryptone means there are 1.2 grams of tryptone in every 100 mL of Terrific Broth. Similarly, 2.4% w/v yeast extract means 2.4 grams of yeast extract per 100 mL.
Since the goal is to prepare 1 liter (1000 mL) of medium, it is necessary to scale up the amounts proportionally. Multiplying both concentrations by 10 (because 1000 mL is 10 times 100 mL), 1.2 grams becomes 12 grams of tryptone, and 2.4 grams becomes 24 grams of yeast extract. After weighing, these components are typically dissolved in approximately 900 mL of distilled water, then the solution is brought up to a final volume of 1 liter. The medium is usually sterilized by autoclaving before use to prevent contamination.
Careful measurement is crucial to ensure consistent nutrient availability for the growing bacteria, as variations in the concentrations can affect growth rates, protein expression, and experimental reproducibility.
