Which of the following statements describes proto-oncogenes?
A) Their normal function is to suppress tumor growth.
B) They are introduced to a cell initially by retroviruses.
C) They are produced by somatic mutations induced by carcinogenic substances.
D) They can code for proteins associated with cell growth.
E) They are underexpressed in cancer cells.

Question

Quizplus · Accepted Answer

Proto-oncogenes are normal genes that can be converted into oncogenes by mutations. Their normal function is related to the promotion of cell growth and differentiation. When mutated, they no longer respond to normal growth controls, leading to uncontrolled cell proliferation and tumor formation. Therefore, option D is the correct choice as it states that proto-oncogenes can code for proteins associated with cell growth.

Option A is incorrect as proto-oncogenes promote cell growth, and their mutations result in uncontrolled cell proliferation. Option B is incorrect as proto-oncogenes are normal genes and are not initially introduced by retroviruses. Option C is incorrect as proto-oncogenes are not produced by somatic mutations induced by carcinogenic substances, but their mutations can be induced in this way. Option E is incorrect as proto-oncogenes are overexpressed in cancer cells, whereas tumor suppressor genes, which are involved in inhibiting cell division or promoting cell death, are underexpressed.

Which of the Following Statements Describes Proto-Oncogenes