Question

1. Cancer is Uncontrolled Mitosis. Cells that no longer respond properly to cell cycle controls often undergo unrestrained cell division forming abnormal tissues called tumors. If these tumor cells stay within the abnormal tissue, then they are deemed benign and may not harm the individual. However, if the tumor cells invade neighboring tissues and spread to other areas of the body where they can form new tumors, then this type of tumor is called malignant and can adversely affect the affected individual. In this exercise you will first determine which set of data, Table 2 or Table 3, corresponds to normal and cancerous cells, based on what is happening with each mitotic stage. Then you will calculate the length of time in minutes that it takes to complete each mitotic stage for the normal and abnormal chicken cells.
   1. (10pts) Fill in the Tables below. Note that each Table requires the use of a different time in minutes for calculations.

TABLE 2: Mitosis in ___________ Chicken Cells
Mitotic Stage	Total # of Cells	% of Total	Time (Minutes)
Interphase	424
Prophase	50
Metaphase	12
Anaphase	3
Telophase	11
Total:	500	100%	448

TABLE 3: Mitosis in ___________ Chicken Cells
Mitotic Stage	Total # of Cells	% of Total	Time (Minutes)
Interphase	440
Prophase	40
Metaphase	8
Anaphase	2
Telophase	10
Totals:	500	100%	62

2. (4pts) Explain in 1-3 sentences how you determined which set of data describes each condition

3. (5pts) After reviewing the tables, discuss which stage (of the whole cell cycle) exhibits the most dramatic difference in timing between normal and cancerous chicken cells. Offer a brief (2-4 sentences) explanation for your result.

Answer 1

1. Filling in the table:

TO CALCULATE PERCENTAGE OF TOTAL, the formula to be used is :

(Number of cells/total number of cells) * 100 = Percentage of total

TO CALCULATE THE TIME IN EACH STAGE = Number of cells at each stage/ total number of cells counted * total time taken

TABLE 2 :

MITOTIC STAGE	% OF TOTAL	TIME (IN MINUTES)
INTERPHASE	84.8	379.9 (84.7%)
PROPHASE	10.1	44.8    (10%)
METAPHASE	2.4	10.75   (2.39%)
ANAPHASE	0.6	2.68     (0.59%)
TELOPHASE	2.2	9.85     (2.19%)

TABLE 3:

MITOTIC STAGE	% OF TOTAL	TIME ( IN MINUTES)
INTERPHASE	88	54.56 (88%)
PROPHASE	8	4.96 (8%)
METAPHASE	1.6	0.99 (1.5%)
ANAPHASE	0.4	0.24 (0.38%)
TELOPHASE	2	1.24 (2%)

2.

Table 2 represents MITOSIS IN NORMAL CHICKEN CELLS ( ONLY IF YOU ARE CONSIDERING THE TIME IN SECOND TABLE IS 62 MINUTES AND NOT 625 WHICH IS ACTUALLY THE CORRECT ONE)

Table 3 represents MITOSIS IN ABNORMAL CHICKEN CELLS (TOTAL TIME TAKEN IS 625 MINUTES) FOR A NORMAL CHICKEN CELL TO REPLICATE

IF THERE IS SOME HUMAN ERROR IDENTIFIED IN PRINTING 62 AND 625, THEN ANSWERS SHOULD BE REVERSED

(TABLE 2 WOULD BE CANCEROUS CELLS AND TABLE 3 WOULD BE NORMAL CELLS)

Basis of determination:

• Cancer cells spend less time in Interphase.
• Accelerated cell division rate

3. INTERPHASE exhibits the most dramatic difference in timing between normal and cancerous chicken cells.

Cancer cells spend less time in growing and duplicating their chromosomes thus entering the mitosis again.