GRE Subject Test: Biology : Understanding Oncogenes

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

Example Question #4 : Genetic Regulation

Which of the following choices could activate a proto-oncogene?

Possible Answers:

Any of these could activate a proto-oncogene

Exposure to mutagens

Chromosomal translocations

Gene duplication

Correct answer:

Any of these could activate a proto-oncogene

Explanation:

Proto-oncogenes are genes that have the ability to become oncogenes (genes that cause cancer). There are many ways to activate proto-oncogenes. Gene duplication can cause an increase in the expression of a particular protein, which can lead to cancer. Exposure to mutagens can cause a mutation on a proto-oncogene, which causes it to become activated. Chromosomal translocations can relocate proto-oncogenes to areas where they are expressed more rapidly. Most proto-oncogenes are involved in cell cycle regulation. Irregular expression of these genes can allow the cell to progress through the cell cycle too rapidly, resulting in unregulated cell division and tumor formation.

Example Question #1 : Understanding Oncogenes

Which of the following best describes an oncogene?

Possible Answers:

A gene that stimulates apoptosis in cells

A gene that causes uncontrollable growth

A gene that regulates cell growth

A gene that no longer makes a viable protein

Correct answer:

A gene that causes uncontrollable growth

Explanation:

Oncogenes can be thought of as cancerous genes, or rather a gene that has the potential to cause cancer. They typically occur when a normal proto-oncogene undergoes a mutation. Proto-oncogenes normally code for growth and development in cells, and tightly regulate these processes. If mutated, these newly cancerous genes can stimulate unregulated growth, a symptom characteristic of cancerous cells.

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