Question

Akt promotes the survival of many cells by affecting the activity of Bad and Bcl2, as diagrammed in Figure Q16-58.

Which of the following statements is false?
(a) In the presence of a survival signal, Akt is phosphorylated.
(b) In the absence of a survival signal, Bad inhibits the cell-death inhibitor protein Bcl2.
(c) In the presence of a survival signal, the cell-death inhibitory protein Bcl2 is active.
(d) In the absence of a survival signal, Bad is phosphorylated.

Answer 1

The false statement is (d) In the absence of a survival signal, Bad is phosphorylated. This is incorrect because, without a survival signal, Bad is not phosphorylated and can inhibit Bcl2, promoting cell death.

Step-by-step explanation:

The false statement in the question about how Akt promotes the survival of cells by affecting the activity of Bad and Bcl2 is (d) In the absence of a survival signal, Bad is phosphorylated. This statement is false because when there is no survival signal, Bad remains unphosphorylated and active, allowing it to bind to and inhibit the cell-death inhibitor protein Bcl2, thus promoting apoptosis.

In contrast, when there is a survival signal, Akt gets phosphorylated (a), leading to the phosphorylation of Bad, which causes Bad to detach from Bcl2 (c), allowing Bcl2 to exert its protective effect and inhibit apoptosis. Therefore, Akt's role is to facilitate the survival of cells upon receiving the correct signals by modulating the activity of proteins involved in the apoptotic pathway.