Download Cell Division Gone Wrong - Stations

Part A – Cell Growth Rates and Cancer
1. a) Use the diagram (at right) to help explain why
malignant tumours are more dangerous than benign tumours.
b) Can you think of any situations in which a benign
tumour could cause problems or become dangerous?
2. a) Explain what you think is happening in the
diagram shown below.
original
tumour
blood
vessel
lymphatic
vessel
b) Define the terms “metastasis” and “malignant”.
Turn over 
3. A physician supplied your laboratory with two samples of the same type of cells: one is normal, and
the other is from a patient who may have a tumour. You were asked to culture the cells, record the
cells’ rates of division, and report back on any abnormalities. Your results are shown in the table
below.
Table 1 – Number of Cells in Samples of Patient X over Time
Time
Population Size
(days)
Normal Cells
Patient X Sample
15
2
2
30
4
6
45
8
10
60
16
30
75
32
92
90
64
180
Question What will you report back to the physician?
Organize, Analyse and Interpret the Data
a) Create a line graph showing the rate of cell division of normal cells and the patient’s cells.
b) Compare the rates of cell division in the two samples.
c) Write a one or two sentence summary of your findings and your interpretation for the physician.
Extend Your Inquiry Skills
d) All cells, whether they are normal or cancerous, need energy. Cell division actually requires more
energy than many other cell activities. Imagine that each cell in your sample needs two units of
energy to divide.
i) Compare the amount of energy used by the cells in each sample at 90 days.
ii) How might this energy requirement affect an individual that has cancer?
Part B – Causes of Cancer
Replication of DNA during interphase usually occurs error-free and the genetic information in daughter
cells is exactly the same as in the parent cell. Sometimes, however, random changes occur in DNA
called mutations.
These mutations may result in the death of the cell or the mutation may be passed on to subsequent
generations through cell division. Very rarely, the mutation may occur in a gene (segment of DNA)
that controls cell division. This will cause the cells to become cancerous. The cells will divide
uncontrollably until all nutrients are exhausted.
1. Use the Microviewer and booklet, “Cancer”, to answer the following questions.
a) Can you identify the abnormal, malignant tissue at the right hand side of the slide?
b) How has lung cancer affected North America?
c) What trend appeared in the early- and mid-1900s for men and women?
d) Why do people keep smoking?
2. Lung cancer is a leading cause of death in both men and women in Canada. It is also a disease
that can be largely prevented. Over a period of time, controllable environmental factors may cause
lung cells to develop one or more of the various forms of lung cancer.
For years, dozens of public health initiatives have targeted smoking-related diseases.
 Protection: reducing the number of Canadians exposed to second hand smoke
 Cessation: supporting and encouraging smokers to quit
 Prevention: preventing young people from taking up smoking
 Harm reduction: mandating changes to tobacco products to reduce their hazards
Table 1 – Prevalence of Smoking in Ontario (Percentage of the population from 1999 to 2005)
Age
1999
2000
2001
2002
2003
2004
2005
Total
15 – 19
25
25
19
19
13*
16
17
20 – 24
34
28
31
29
29
21
24
25 – 44
29
28
21
24
22
22
26
45+
16
17
17
14
14
11
12
15 – 24
32
27
26
25
22*
21
23
25+
24
25
23
21
22
22
23
15 – 24
27
26
24
23
20*
16
18
25+
20
20
15
17
14*
10
14
Male
Female
*low sampling (six months of data)
a) Were the males or females of ages 15 to 24 more likely to smoke in 1999 or 2005?
b) Does it appear that campaigns to reduce smoking over the years 1999 to 2005 were
successful? What assumption do you have to make in order to draw this conclusion?
c) Would you say that the change in smoking rates during this time period were major or minor?
Explain.
Part C – Cancer Screening
Cancer screening involves checking for cancer even if there are no symptoms. Depending upon the
type of cancer, it can involve routine self- examination at home, routine medical check-up or by special
appointment.
Screening is especially recommended if there is a family history of cancers such as breast cancer or
colon cancer. Screening is also valuable to those who are exposed to carcinogens at work or by
lifestyle. Genetic screening is an option to determine if you have inherited the gene linked to cancer.
Screening does not prevent cancer, but provides early detection and allows for early treatment.
Women can self-screen for breast cancer by checking for lumps. The Pap test is used to check for
cervical cancer by examining cervical cells.
Men can check for lumps to screen for testicular cancer. A blood test called PSA screens for prostate
cancer. This is generally done above the age of 50.
A colonoscopy is often done starting at age 50, every ten years using optics to screen for polyps in the
colon which may be cancerous.
Moles should be checked by a doctor or dermatologist using the “ABCD” for moles.
A: asymmetry, B: border, C: colour and D: diameter.
(Note: These do not count as bold words.)
1. Record a minimum of two types of screening that apply to you.
Part D – Reducing Your Cancer Risk
Most experts believe that cancer rates can be reduced dramatically with changes in lifestyle. Any
substance or energy that causes a mutation in the genes that regulate cell division, resulting in cancer,
is called a carcinogen.
1. Study the pie chart in Figure 1 that shows the risk factors associated with cancer.
a) Which factor is responsible for the most cancer cases?
b) Which of the cancer causes could be reduced by changes in lifestyle?
c) List at least three lifestyle changes that could reduce cancer rates.
Figure 1 – Estimates of Risk Factors
(Note: the legend goes clockwise around the chart, starting with the tobacco wedge.)
tobacco
2. a) Complete the table provided on your worksheet by calculating the survival rates for the different
types of cancer.
b) Based on the data, which type of cancer is the most deadly?
3. The Sun is necessary for all life on Earth, but it is also the source of ultraviolet (UV) radiation, which
is harmful to your skin cells. There are things that you can do to protect your skin.
Add your group’s responses to the following three survey questions, toward the end of class tally the
results and record the percentages in order to answer the questions.
Survey
i) Do you regularly practice Sun protection behaviours in the summer?
ii) Did you suffer at least one major sunburn in the summer?
iii) How many hours per day do spend in the Sun during the summer?
a) Does your data suggest that youth are practicing Sun protection behaviours?
b) What is one action that you could take to encourage your friends and family to practice Sun
protection behaviours?
Turn over 
4. Provide some reasons to explain the relationship between this picture and cancer.
Part E – Diagnosing & Treating Cancer
1. The main difficulty in detecting cancer is that the appearance of symptoms depends on how fast the
cancer cells are dividing. The rate of cancer growth is measured in doubling times. One doubling
time is the length of time it takes for the cancer cells to double in number. Doubling times for different
types of caner cells vary from 10 days to several years. The average doubling time for a cancer cell is
four months.
a) Explain how you know which cells in the diagram are cancerous.
b) It takes about 30 doubling times for a cancer cell to form a tumour that is large enough to be felt
through the skin with the hands. Calculate how many months it would take for cells in the diagram to
form a tumour that could be felt if the doubling rate is two months.
c) What are the limitations of visual inspection as a diagnostic tool for cancer?
2. Cancer may be diagnosed by detection of a lump which may or may not be causing discomfort.
The individual may be experiencing fatigue or unexplained weight loss. Once suspected, the doctor
may order blood tests or imaging techniques.
Use the internet to give a brief explanation of the following imaging techniques:
a) endoscopy
b) X-ray
c) ultrasound
d) CT scanning
e) MRI
3. What is a biopsy?
4. The goal of cancer treatment is to slow down the growth of the tumours or destroy as many cancer
cells as possible.
Surgery – If the tumour or cancerous tissue is easily accessed and is well defined, it may be
surgically removed.
Chemotherapy – Drugs are used to slow or stop cancer cell division and metastasis and to kill the
cells. Side effects may include hair loss, nausea and fatigue. Chemotherapy is often the first stages of
cancer treatment. It is used to shrink a tumour for surgical removal or for radiation treatment. The
bloodstream is used to transport the drugs throughout the body.
Radiation – Ionizing radiation disrupts cell division in rapidly dividing cancer cells. A focused beam is
used to target the tumour or a radioactive source is implanted into the tumour.
A New Treatment – Biophotonics
This technology uses light energy to diagnose, monitor and treat cancer. It has fewer side effects than
conventional treatments. Much of the research into this technique occurs at University of Toronto.
a) Why might there be a risk of cancer recurring, even when surgery is performed to remove a
malignant tumour?