LESSON 5 How do bacteria grow Purpose Prediction

LESSON 5: How do bacteria grow?

Purpose & Prediction -SAS # 1 & 2 So to look back at our last lesson, answer the Purpose and Prediction questions in your SAS (? 1 & 2) What did we decide we wanted to investigate last time? If you could zoom in really close to see what was happening during bacterial growth, what do you think you would see?

Investigation 1: Time-lapse Bacteria Growth Record your observations & answer ? SAS # 3&4

Making Sense of Investigation 1: With a partner use your calculators to complete # 5 on your SAS

Creating a Mathematical Model for Investigation 1: SAS #6 Time (in min) Time (in hours) Number of Bacteria 0 0 1 So in the video, we found out that bacteria split into 2 new bacteria about every 20 minutes! Let’s visualize this using sticky notes to help us identify a pattern we can use to develop our table. . .

Constructing a Graph for Investigation 1: SAS #6 What should be the title of the graph? What should we label the x-axis and the yaxis? What should the intervals be on the x-axis? What should the intervals be on the y-axis? (Make sure you are using constant intervals and use as much of the graph space as possible - this makes it much easier to see patterns of change!)

Building Understandings Discussion ● What did we discover in this investigation that helps answer our question, “Why did some of the Petri dishes appear to have no bacteria present and then days later they had visible bacteria? ” ● What are the spots we saw on our Petri dishes made of? ● Is an individual bacterium made of one or many cells? ● How would we summarize the process by which bacteria reproduce? ● How is food related to what happens in this process? ● Why would cells need to make new (extra duplicate) cell parts before they reproduce? ● What was the pattern of growth in the size of the population? Capture these ideas on your Tracker & SAS #7

Update our Tracker How can we summarize what we see in the growth of bacteria? Should we change our model for this situation? Name: How do bacteria grow? Nickname: Video of bacteria growing

L 5: How do bacteria grow? Video of Bacteria Growing What should we add to our models: Addie’s mom waited at first to take her to the hospital. In this time the bacteria started growing slowly, which is why her condition wasn’t terrible at first. Then the bacteria exponentially increased and she became very sick very fast.

What happens next? Would the bacteria continue to grow exponentially if left in Petri dishes?

Next steps. . . It sounds like we have some different predictions about whether or not the exponential growth would continue to hold into the future and for how long… Sometimes when systems like this get really complex, scientists use computer models to predict what could happen. If we wanted to simulate this system on a computer, what sorts of things would it be important to show in the simulation?

Scientists often build computer simulations to help investigate and visualize outcomes in systems that have parts in them that are too small to see. Computer simulations are programmed to have the objects & interactions that the user wants or needs. Think about what YOU would want to see included that would help you understand, explore, and predict HOW bacteria reproduce in a Petri dish. How would you want the computer to simulate a constant rate of bacterial growth? How would we want to visualize or keep track of one line of descendents from one bacterium vs. a line from another bacterium? What would be a reasonable assumption to include in the simulation for what happens to bacteria growth when they reach the wall of the Petri dish, where there is no agar? What sort of data would you want the simulation to graph automatically for you?