Answers to Concept Checks

WORKED PROBLEMS

Problem

In some cancer cells, a specific gene has become duplicated many times. Is this gene likely to be an oncogene or a tumor-suppressor gene? Explain your reasoning.

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Solution Strategy

What information is required in your answer to the problem?

Whether the gene is likely to be an oncogene or tumor-suppressor gene and why.

What information is provided to solve the problem?

In cancer cells, the gene has been amplified many times.

For help with this problem, review:

Oncogenes and Tumor-Suppressor Genes in Section 23.2.

Solution Steps

The gene is likely to be an oncogene. Oncogenes stimulate cell proliferation and act in a dominant manner. Therefore, extra copies of an oncogene will result in cell proliferation and cancer. Tumor-suppressor genes, on the other hand, suppress cell proliferation and act in a recessive manner; a single copy of a tumor-suppressor gene is sufficient to prevent cell proliferation. Therefore, extra copies of the tumor-suppressor gene will not lead to cancer.

Recall: An oncogene is an accelerator to cell division, while a tumor-suppressor gene is a brake.