Question

Regarding chemical carcinogenesis, what distinguishes initiators from promoters?

A) Initiators induce cell mutations, while promoters initiate tumor growth.
B) Initiators cause irreversible mutations, while promoters trigger reversible changes.
C) Initiators are specific for certain tissues, while promoters affect all tissues.
D) Initiators directly cause cancer, while promoters only facilitate its progression.

Answer 1

Initiators directly cause cancer by inducing irreversible genetic mutations, while promoters facilitate cancer progression by promoting the growth of initiated cells without causing mutations themselves. Thus, the correct answer is option D) Initiators directly cause cancer, while promoters only facilitate its progression.

Step-by-step explanation:

Chemical carcinogenesis involves two stages: initiation and promotion. Initiators, such as certain carcinogenic chemicals, cause irreversible genetic mutations in the DNA of target cells. These mutations are typically permanent alterations that can lead to the initiation of cancer. On the other hand, promoters do not directly induce mutations but play a crucial role in promoting the growth and progression of initiated cells into tumors. Promoters often act on already initiated cells, stimulating their proliferation and enhancing the development of cancer.

In summary, initiators directly contribute to the initiation of cancer by causing genetic mutations, while promoters facilitate the progression of initiated cells into malignant tumors without causing mutations themselves. This distinction highlights the sequential nature of chemical carcinogenesis, where initiation precedes promotion in the development of cancer.

Thus, the correct answer is option D) Initiators directly cause cancer, while promoters only facilitate its progression.