Question

Which of the following genetic changes cannot convert a proto-oncogene into an oncogene? A mutation in the promoter of the proto-oncogene, causing the normal protein to be transcribed and translated at an abnormally high level. A mutation that introduces a stop codon immediately after the codon for the initiator methionine. An amplification of the number of copies of the proto-oncogene, causing overproduction of the normal protein. A mutation within the coding sequence that makes the protein hyperactive. A genetic rearrangement where proto-oncogene coding sequence becomes fused with the promoter of a highly active promoter.

Answer 1

Answer:

A mutation that introduces a stop codon immediately after the codon for the initiator methionine.

Explanation:

Pro oncogene is a gene altered by mutation.

Activating mutation of one of the two alleles of a proto-oncogene is what converts it to an oncogene. This can induce transformation in cultured cells or cancer in animals. Activation of a proto-oncogene into an oncogene can occur by point mutation, gene amplification, and gene translocation.

Answer 2

Answer:

The correct option is B:

"A mutation that introduces a stop codon immediately after the codon for the initiator methionine."

Explanation:

There are multiple ways through which a proto-oncogene can get converted to an oncogene. It could either be due to a point mutation that occurs in the gene (or even its promoter), or amplification of the gene as a result of increased copies of the proto-oncogene that causes the normal protein to be produce in a larger quantity than needed. Gene translocation is yet another cause for its activation. However, a stop codon being introduced right after the start codon will not lead to activation of proto-oncogene, that will simply result in the production of a truncated, non-functional protein that will be degraded by the cellular machinery.

Hope that answers the question, have a great day!