CHAPTER 10 Test Your Knowledge
Driving Question 1
What are mutations, and how can they occur?
By answering the questions below and studying Infographics 10.1, 10.2, 10.3, and 10.4, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
In an otherwise normal cell, what happens if one mistake is made during DNA replication?
a. Nothing; mistakes just happen.
b. A cell cycle checkpoint detects the error and pauses the cell cycle so the error can be corrected.
c. The cell will begin to divide out of control, forming a malignant tumor.
d. A checkpoint will force the cell to carry out apoptosis, a form of cellular suicide.
e. The mutation will be inherited by the individual’s offspring.
Why does wearing sunscreen reduce cancer risk?
a. Sunscreen can repair damaged DNA.
b. Sunscreen can activate checkpoints in skin cells.
c. Sunscreen can reduce the chance of mutations caused by exposure to UV radiation present in sunlight.
d. It doesn’t; sunscreen causes mutation and actually increases cancer risk.
e. Sunscreen can prevent cells with mutations from being destroyed.
Are all mutations bad? Explain your answer.
USE IT
The mutation illustrated in Infographic 10.4 inserted an A in the third codon of the mRNA shown. Use the genetic code (Infographic 8.10, p. 176) to match each mutation below (all are mutations of the normal mRNA sequence shown in Infographic 10.4) with its effect on the protein.
Mutation
Substitution of an A for the C in the third codon
Substitution of a C for the U in the fourth codon
Substitution of an A for the first C in the second codon
Effect
____ Protein will have an incorrect amino acid in its sequence.
____ No impact on the protein
____ Protein will be shorter than normal.
Driving Question 2
How does cancer develop, and how can people reduce their risk?
By answering the questions below and studying Infographics 10.3, 10.4, 10.5, and 10.7, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
What are some differences and some similarities between tumor suppressor genes and oncogenes?
What is the role of BRCA1 in normal cells?
Which of the following can cause cancer to develop and progress?
a. a proto-oncogene
b. an oncogene
c. a tumor suppressor gene
d. a mutated tumor suppressor gene
e. b and d
f. b and c
USE IT
What would you say to a niece if she asked you how she could reduce her risk of breast cancer? (Assume there is no family history of breast cancer.) How might each of your suggestions reduce her risk?
Why is age a risk factor for cancer?
Driving Question 3
Why do people with “inherited cancer” often develop cancer at a relatively young age?
By answering the questions below and studying Infographics 10.1, 10.6, and 10.7, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
A woman with a BRCA1 mutation
a. will definitely develop breast cancer.
b. is at increased risk of developing breast cancer.
c. must have inherited it from her mother because of the link to breast cancer.
d. will also have a mutation in BRCA2.
e. b and c
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Which of the following family histories most strongly suggests a risk of inherited breast cancer due to BRCA1 mutations?
a. many female relatives who were diagnosed with breast cancer in their 70s
b. many relatives with skin cancer
c. many relatives diagnosed with skin cancer at an early age
d. many female relatives diagnosed with breast cancer at an early age
e. many female relatives with both early breast cancer and ovarian cancer
USE IT
Lorene Ahern was born with an inherited predisposition to cancer. At the cellular and genetic level, what was she born with? At birth, were cells in her breast genetically identical to cells in her liver? Now that she has breast cancer, are her cancer cells genetically identical to her normal breast cells? Explain your answers.
Which of the following women would be most likely to benefit from genetic testing for breast cancer?
a. a 25-year-old woman whose mother, aunt, and grandmother had breast cancer
b. a healthy 75-year-old woman with no family history of breast cancer
c. a 40-year-old woman who has a cousin with breast cancer
d. a 55-year-old woman whose older sister was just diagnosed with breast cancer
e. All women can benefit from genetic testing for breast cancer.
People like Lorene Ahern have inherited a mutated version of BRCA1. Why does this mutation pose a problem? Why are these people at high risk of developing breast cancer when they still have a functional BRCA1 allele? Describe how the protein encoded by normal BRCA1 compares to that encoded by mutant alleles of BRCA1.
MINI CASE
Nellie has a family history similar to Lorene Ahern’s. Nellie’s mother died at an early age from breast cancer, as did her maternal aunt (her mother’s sister). Nellie is not yet 35 but has started having annual mammograms. She has also been tested for BRCA1 and BRCA2 mutations. She has a BRCA2 mutation and is considering prophylactic surgery. Her younger sister, Anne, doesn’t want to know the results of Nellie’s genetic testing because if Nellie has a BRCA2 mutation, then there is a chance that Anne could have inherited the same mutation from their mother. Does Nellie or Nellie’s doctor have an obligation to tell Anne about the test results? What about Nellie’s older brother? Should he be told? There are personal and medical benefits and risks to consider here.
INTERPRETING DATA
Refer to Infographic 10.8 to answer the following questions.
a. What is the average percentage of BRCA1 carriers who develop breast cancer by age 50?
b. Exactly how many times more likely are BRCA1 carriers to develop breast cancer by age 50 compared to the general population?
c. What is the average percentage of BRCA1 carriers who develop breast cancer by age 70%
d. Exactly how many times more likely are BRCA1 carriers to develop breast cancer by age 70 than the general population?
e. Why are both carriers and noncarriers more likely to have developed breast cancer by age 70 than by age 50?
BRING IT HOME
If you wanted to change your lifestyle to reduce your risk of developing cancer, what specific steps could you take with respect to each of the following? Be as specific as you can. Take your age and gender into consideration as you consider each factor.
a. alcohol consumption
b. sun exposure
c. tobacco use
d. exposure to pesticides
e. meat preparation (cooking method)