lab - Time 5 min 10 min 15 min 20 min Figure 1 Movement NO...

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% Motility Sample 100% 1 0% 2 10% 3 15% 4 25% 5 30% 6 30% 7 Time Movement Behavior 5 min NO NONE 10 min NO NONE 15 min NO Cells are expanding 20 min NO Cells are still getting bigger 25 min NO Cells are still expanding 30 min NO The cells are starting to separate
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Figure 1 For the first stimulus experiment, we took a small amount of Chlamydomonas culture and added a few drops of TAP. I had predicted that, as time passed, the culture would eventually become motile due to the TAP. I predicted that, by the 30 minute mark, most of the Chlamydomonas would be swimming around. However, as you can see in Figure 1, this was not the case. By the time 30 minutes had passed, the culture was just starting to absorb the TAP and the cells were getting slightly bigger, but there were no signs of any sort of life present. Figure 2 For the second stimulus experiment, we shocked a sample of Chlamydomonas by reducing the pH of the culture to about 4.5, causing them to shed their flagella. Sample 1 in Figure 2 was taken before this shock occurred. We used this as our positive control. After the shock, we took another sample-Sample 2, which we used as our negative control. We then added potassium hydroxide to the culture to return the pH to approximately 6.5, which is a neutral pH, allowing the Chlamydomonas to regenerate their flagella. After the pH was
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neutralized, we took a sample of the culture every 5 minutes until 15 minutes had passed, then we took another sample every 15 minutes. For each sample, we made three slides- one slide with the live culture to determine % motility , another live slide to determine the behavior of the Chlamydomonas, and a third slide to determine the length of the flagella that had been regenerated. We classified the lengths using the following scale from the lab manual: 0= flagella are not visible 1= flagellar stumps are barely visible 2=flagella are less than 1/2x the length of the cell 3= flagella are between 1/2x and 1x the length of the cell 4= flagella are 1-1.5x longer than the long axis of cell 5= flagella are 2 or more times longer than the long axis of the cell. The results for percent motility can be seen in Figure 3, the behavior is described in Figure 4, and the length of the flagella is represented by Figure 5 below. I had predicted that the longer we allowed the Chlamydomonas to recover from the pH shock, the longer the flagella would be, an the percent motility would correspond positively with the length of the flagella. As you can see from the figures, my prediction was correct. Time Behavior 5 min Slightly motile 10 min More are motile, but there are many that are still not moving 15 min Many are motile; a few are swimming in circles 30 min Most are swimming, must faster than before
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45 min Almost all are swimming, most are fast, but there are still some going in circles. Figure 3
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This note was uploaded on 03/30/2008 for the course BIO BS 111 taught by Professor Lab during the Spring '08 term at Michigan State University.

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lab - Time 5 min 10 min 15 min 20 min Figure 1 Movement NO...

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