1. Learning Targets “I Can…” -Focus a slide under a microscope by always starting with the objective (the red) to observe living yeast cells. -Predict the outcome of yeast growth over a certain time period on a graph. -Define “exponential growth.” -Draw/Interpret a graph for a population that is experiencing exponential growth.

2. Population Dynamics Examining a Closed Population

3. Yeast Cells (Microscopic View)

4. BuddingBudding Yeast Cells

5. Yeast Cells Reproducing

6. What is a closed population? Populations normally change in size as individuals reproduce, die, and move in and out of an area. A closed population is one that does not experience migration, so the population number changes only through births and deaths.

7. What you will do today… You will be given yeast cells that have been placed in a closed environment with lots of food (apple cider). Growth of the yeast cells will be observed under the microscope and by using turbidity over a period of nine days.

8. Make a prediction... NUMBER OF YEAST CELLS TIME IN DAYS

9. What is turbidity? Turbidity is the cloudiness of a solution.

10. What is turbidity? To measure turbidity, we use a Colorimeter.

11. What is turbidity? The Colorimeter measures the amount of light absorbed by the yeast cells. The more yeast cells there are, the cloudier the suspension, the more light that is absorbed.

12. Make a prediction... ABSORBANCE TIME IN DAYS

13. Procedures 1.Prepare a slide for your control. Prepare a slide for your experimental. BE SURE TO USE SEPARATE PIPETTES! 2. Count the number of yeast cells on each slide under the BLUE objective. 3.Fill the labeled cuvettes with the appropriate sample to about ¾ full. 4.Measure the absorbance of each sample using the colorimeter. 5.Record all of your values on the data table on the front table. 6.Discard your sample down the sink, throw away all used pipettes and coverslips, and rinse your test tubes and cuvettes. 7.Return your microscope to the cabinet.

17. References http://bugs.bio.usyd.edu.au/learning/resour ces/CAL/Microconcepts/images/Topics/Div ersity/buddingYeastCells.jpghttp://bugs.bio.usyd.edu.au/learning/resour ces/CAL/Microconcepts/images/Topics/Div ersity/buddingYeastCells.jpg http://etc.usf.edu/clipart/15400/15447/grwy eastcell_15447_lg.gifhttp://etc.usf.edu/clipart/15400/15447/grwy eastcell_15447_lg.gif http://www.public.asu.edu/~jpbirk/qual/qua lanal/WHITE/Ca4ppt.gifhttp://www.public.asu.edu/~jpbirk/qual/qua lanal/WHITE/Ca4ppt.gif http://www.copcoinc.com/uploads/col- bta_web-0-0.jpghttp://www.copcoinc.com/uploads/col- bta_web-0-0.jpg https://www.youtube.com/watch?v=BTHYa f-EuYshttps://www.youtube.com/watch?v=BTHYa f-EuYs