Mitosis Lab

Ocular lens - 10X

Objectives - 4X- 10X - 40X

Total Magnificationx 10X = 40Xx 10X = 100Xx 10X = 400X

Diaphragm – adjusts light & heat

How to use the microscope1. Turn on – crank dial to 102. Adjust light with diaphragm3. Place slide in corner & release

retractable arm….gently!!!!!!4. Using scanning lens (4X), focus

on sample with coarse focus5. Change objective (if needed)6. Repeat

Mitosis Lab

Mitosis Lab

Figure 12.10

Mitosis Lab

1. If your observations had not been restricted to the area of the root tip that is actively dividing, how would your results have been different?

2. Why did we choose to use the onion root tip to study mitosis?

3. Calculate the percentage of cells in each stage. Consider that it takes (on average) 24 hours (1440 min) for onion roots tip cells to complete the cell cycle. Knowing this, you can calculate the amount of time spent in each phase of the cell cycle from the percentage of cells found in each stage of mitosis. (Recall 90% of time is spent in interphase.)

% of cells in stage (decimal) X 144 min = _____ minutes in that stage

(mitotic phase)

4. Draw an example of each stage.

Prophase Metaphase Anaphase Telophase

= 25 cells

Table 3.1