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Mega Multiplies of MicrobesGoal:To visualize large numbers and calculate microbial population rmation to Think About:Microbes divide, forming new cells. That is, 1 cell forms 2 new cells in a certain period of time often is called a generation. Then the 2 cells divide, forming a total of 4 new cells. These 4 cells can all divide, forming a total of 8 cells. In each generation, the number of cells in the microbial population doubles.Materials:PencilPaperCalculatorProcedures: Determine how many cells are formed from a single cell in 20 generations. Do this on a sheet of paper by:Beginning with 1 cell and doubling it (multiply by 2) – this is the first generation.Multiply the number 2 by 2 for the number of cells at the end of the second generation.Multiply this number by 2 to determine the number for the third generation.Continue with this process until you arrive at the 20th generation _________Compare your numbers with those obtained by the others in your group.Calculate the number of individuals produced after 40 generations, using the same method.____________________________________Graph the information that you obtained from the 1st, 20th and 40th generations.Mega Multiplies of MicrobesGoal:To visualize large numbers and calculate microbial population rmation to Think About:Microbes divide, forming new cells. That is, 1 cell forms 2 new cells in a certain period of time often is called a generation. Then the 2 cells divide, forming a total of 4 new cells. These 4 cells can all divide, forming a total of 8 cells. In each generation, the number of cells in the microbial population doubles.Materials:PencilPaperCalculatorProcedures: Determine how many cells are formed from a single cell in 20 generations. Do this on a sheet of paper by:Beginning with 1 cell and doubling it (multiply by 2) – this is the first generation.Multiply the number 2 by 2 for the number of cells at the end of the second generation.Multiply this number by 2 to determine the number for the third generation.Continue with this process until you arrive at the 20th generation _________Compare your numbers with those obtained by the others in your group.Calculate the number of individuals produced after 40 generations, using the same method.____________________________________Graph the information that you obtained from the 1st, 20th and 40th generaConclusion Questions:How is the growth rate of microbes calculated?Using the graph:Why does bacterial growth look like exponential growth? (Exponential growth= the value or amount of something increases in the same amount that the rate increases. For example, when the value doubles, so will the rate.)Fred was making a macaroni salad, but he couldn’t find a spoon so he used his hands to mix in the dressing. There were four S. aureus bacteria on his hands, which contaminated the salad. Fred then took the salad to a picnic, where it was left out, unrefrigerated for two hours. How many S. aureus grew in the salad? Was this salad safe to eat? (hint: it takes 20 minutes to double once)Challenge: Why would a researcher testing bacterial growth place a petri dish (with bacteria already swabbed on the agar) into an incubator?Conclusion Questions:How is the growth rate of microbes calculated?Using the graph:Why does bacterial growth look like exponential growth? (Exponential growth= the value or amount of something increases in the same amount that the rate increases. For example, when the value doubles, so will the rate.)Fred was making a macaroni salad, but he couldn’t find a spoon so he used his hands to mix in the dressing. There were four S. aureus bacteria on his hands, which contaminated the salad. Fred then took the salad to a picnic, where it was left out, unrefrigerated for two hours. How many S. aureus grew in the salad? Was this salad safe to eat? (hint: it takes 20 minutes to double once)Challenge: Why would a researcher testing bacterial growth place a petri dish (with bacteria already swabbed on the agar) into an incubator? ................
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