bio 3709 ch23

Select the statements that accurately describe different ways that translocations could lead to cancer.

-A translocation breaks up the sequence of a gene for a tumor-suppressor protein. The resulting protein cannot function properly. -A new sequence is added to a proto-oncogene. The modified gene now produces a new protein that increases the rate of cell division. -A gene for a protein that regulates the cell cycle is placed next to the regulatory sequence of a different gene. The gene is now expressed in response to different stimuli.

Colon cancer is caused by the accumulation of multiple gene mutations that result in uncontrolled cell division and growth. Arrange the following steps of colon cancer progression.

1. Colon tissue is intianlly healthy 2. Inactivating APC mutations give rise to bening polyps(polys or early adenomas) 3. Activating RAS mutations gives rise to intermediate adenomas 4. Late adenomas are formed by the inactivation of DCC and SMAD4 5. Adenocarcinomas are generated by mutation in p53(cancerous adenomas 6. Adenocarinomas become metastatic by unknown mutations (cancerous adenomas become) 7. Color cancer invades neighboring tissues.

Suppose Alia recently learned that she inherited a mutant BRCA1 allele from her mother, who had breast cancer. BRCA1 is a tumor suppressor gene that is related to breast cancer. Why would Alia be at higher risk for getting breast cancer at an earlier age than her sister, Francine, who inherited a normal BRCA1 allele from their mother?

A person who inherited two functioning alleles of a tumor suppressor gene needs both alleles to mutate for tumors to develop.

Which of the following increase the risk of developing cancer?

Being obsese Using tobaco producs Getting UV light exposurwe Getting less than 2 hrs of physical exercise a week Over-consuming alcohol Having a diet rich animal fat and processed meat

How do viruses contribute to cancer? Select all that apply.

By inactivation tumor-suppressor genes By driving overexpression of a cellular proto-oncogene.

Cancer cells divide uncontrollably, evading the signals that regulate the cell cycle. Classify the characteristics below as those of cancer cells or normal cells.

Cancel cells: Have abnormal number of chromosomes Enter new tissues and grow there Do not respond to external cell signals Normal cells: Differentiate into specialized cells Undergo apoptosis if genome is damaged Adhere to neighboring cells within a tissue

1. Which of the following is not true regarding cancer cells?

Cancer cells respond to normal cell cycle controls but proliferate at an abnormal rate.

Select the viruses that can cause human cancer.

Hepatitis C HPV EPSTEIN BARR virus

In general, what causes normal cells to become cancer cells?

Loss of cell cycle control

Cancer is a genetic disorder. How does cancer differ from most other genetic disorders?

Most genetic disorders are inherited through germ cells from parents. Most cancers are, to some extent, the result of mutations in somatic cells that occur during an organism's lifetime.

4. Mutant versions of genes that are normally involved in driving the cell cycle are known as _____.

ONCOGENES

Match each definition with the corresponding term concerning genes involved in tumor formation.

Proto-oncogenes: a normal gene that drives inappropriate cell division if abnormal over-expressed Oncogenes: a mutated gene that promotes inappropriate cell division and tumor formation. Tumor suppressor genes: a gene that protects a cell from progressing toward cancer Haplo insufficiency: a condition in which a single copy of a gene fails to produce enough gene products for normal function.

6. Tumor-suppressor genes typically act in a ______________ manner, and oncogenes typically act in a _______________ manner.

RECESSIVE, DOMINANT

3. Which of the following statements best describes Alfred Knudson's "two-hit hypothesis?"

Retinoblastoma results from two separate genetic defects, both of which are necessary for cancer to develop.

5. Genes that normally produce factors that inhibit cell division are called _____.

TUMOR SUPPRESSOR GENES

7. How might a mutation in a gene that regulates telomerase lead to cancer?

The mutation could allow telomerase to be expressed when it should not be.

8. Which of the following is not a way in which chromosome mutations could lead to cancer?

Translocation of a tumor-suppressor gene to a new location puts it under the control of a strong promoter.

2. Which of the following statements best describes the clonal evolution of tumors?

Tumor cells acquire more somatic mutations that allow them to become increasingly more aggressive in their proliferative properties.

Which of the following mutations have the potential to cause cancer?

a loss-of-function mutation in a tumor suppressor gene a gain-of-function mutation in a proto-oncogene