Question

discussion:
the amount of time that onion cells spend in each phase of the cell cycle can be
estimated by looking at the percentages you just recorded. if 5% of the cells were in
prophase, we can estimate that an onion cell spends 5% of its time in prophase.
make a pie chart to represent the cell cycle for an onion root tip cell.

if you haven’t made a pie chart before, here’s an example to show you how to do it.
example:
5% of the cells were in prophase.
that means that 5% of the cell cycle is spent in prophase.
to calculate the slice of pie that represents 5%, we take .05 x 360. 360 is the
number of degrees in a circle, which is our full pie.
.05 x 360 = 18

the slice of pie that represents prophase is 18° on a circle. using a
protractor, make a perfectly straight light at the top of the circle and then another line 18°
from that one. it should look like the picture below.
onion cell cycle
prophase (5%)

calculations:
calculate the degrees of a circle for each phase of mitosis that you saw in the onion cells:
interphase prophase metaphase anaphase telophase
degrees

draw your onion cell cycle pie chart on the next page. be sure to label the percentages
for each section of the pie.

Explanation:

Step1: Recall the formula

To find the degrees for each phase in the pie chart, we use the formula: Degrees = (Percentage of cells in phase) × 360. The percentage should be converted to a decimal (e.g., 5% becomes 0.05).

Step2: Apply the formula to each phase

For each phase (Interphase, Prophase, Metaphase, Anaphase, Telophase), we need the percentage of cells observed in that phase. Let's assume we have the percentages (for example, if Interphase is 60%, Prophase 15%, Metaphase 5%, Anaphase 10%, Telophase 10% - these are typical values, but actual values depend on observation):

• Interphase: If percentage is \( p_{I} \), Degrees \( = p_{I} \times 360 \). For \( p_{I}=0.6 \), \( 0.6\times360 = 216 \)
• Prophase: If percentage is \( p_{P} \), Degrees \( = p_{P} \times 360 \). For \( p_{P}=0.15 \), \( 0.15\times360 = 54 \)
• Metaphase: If percentage is \( p_{M} \), Degrees \( = p_{M} \times 360 \). For \( p_{M}=0.05 \), \( 0.05\times360 = 18 \)
• Anaphase: If percentage is \( p_{A} \), Degrees \( = p_{A} \times 360 \). For \( p_{A}=0.1 \), \( 0.1\times360 = 36 \)
• Telophase: If percentage is \( p_{T} \), Degrees \( = p_{T} \times 360 \). For \( p_{T}=0.1 \), \( 0.1\times360 = 36 \)

(Note: Actual values depend on the observed percentages from the onion cell experiment. The above are example calculations.)

Answer:

To calculate the degrees for each phase, use \( \text{Degrees} = (\text{Percentage of cells in phase}) \times 360 \). Substitute the observed percentage (as a decimal) for each phase into this formula to get the degrees for the pie chart slice. For example, with typical percentages: Interphase \( \approx 216^\circ \), Prophase \( \approx 54^\circ \), Metaphase \( \approx 18^\circ \), Anaphase \( \approx 36^\circ \), Telophase \( \approx 36^\circ \) (values vary by observation).