1. Microbiology November 2013

2. Agenda Warm-up (E. coli example- complete table and graph) Quick review of b = B x 2 n Solving for generation time Practice problems

3. Test # 3 Test on bacterial growth will likely be next Friday (11/22) NB check 1 for Q2 next Friday Guided notes from gram staining, bacterial growth Solved practice problems Next week, you’ll add notes on factors affecting bacterial growth Test will have: gram staining (questions and practical stations); binary fission; growth problems (number of cells present, calculating generation time, graphing)

4. Review b = B x 2 n What do b, B, and n stand for? Solve: Suppose the generation time of a bacterium is 12 minutes and the initial number of cells in a culture is 62 cells. How many bacteria will be present after 15 hours of exponential growth?

5. Solved Solve: Suppose the generation time of a bacterium is 90 minutes and the initial number of cells in a culture is 580 cells (B). How many bacteria will be present after 8 hours of exponential growth? b = B x 2 n n = 8(60) / 90 480/90 5.33 b = 580 x 2 5.33 23,330 cells

6. Quiz! <3 “More Challenging Graphing Practice Problems” Not graphing these #1: 2 will be raised to a decimal power (ie 2^.25) When done, flip over and wait to switch with a partner

7. Answers 1. 1000 x 2^.75= 1,681.8 bacteria cells 2. 6000 x 2^12 = 24,576,000 bacteria cells 3. 1 x 2^24 = 16,777,216 4. 100 x 2^48 = 2.8 x 10^16

8. Finding Generation Time b = B x 2^n To find n, you need to use logarithms Logarithm: a quantity representing the power to which a fixed number (the base) is raised to produce a given number Example: a jar has 10,000 bacteria cells in it at 11 AM. It started with 3 bacteria cells at 9 AM. What is the generation time of this bacteria? 10,000 = 3 x 2^n (10,000)/3 = 2^n 3333.3 = 2^n n = log (3333.3) / log (2)  always log (2) on bottom because of the exponential growth rule (increase by a factor of 2) n = 3.5 /.301 = 11.7 GENERATIONS To find generation time, take total time and divide by n 120/11.7 = 10.3 minutes for generation time

9. Practice Problems Numbers 1 and 2 When done, pick up “Quiz Review Practice A” and complete this ON YOUR OWN.