The Ras protein is a GTPase that functions in many growth-factor signaling pathways. In its active form, with GTP bound, it transmits a downstream signal that leads to cell proliferation; in its inactive form, with GDP bound, the signal is not transmitted. Mutations in the gener for Ras arefound in many cancers. of the choices below, which alteration of Ras activity is most likely to contribute to the uncontrolled growth of cancer cells? a. a change that prevents Ras from being made b. a change that increased the affinity of Ras for GDP c. a change that decreases the affiniity of Ras for GTP d. a change that decreases the rate of hydrolysis of GTP by Ras

Question

Biology

Joyce Wilcox

27 February, 12:33

The Ras protein is a GTPase that functions in many growth-factor signaling pathways. In its active form, with GTP bound, it transmits a downstream signal that leads to cell proliferation; in its inactive form, with GDP bound, the signal is not transmitted. Mutations in the gener for Ras arefound in many cancers. of the choices below, which alteration of Ras activity is most likely to contribute to the uncontrolled growth of cancer cells? a. a change that prevents Ras from being made b. a change that increased the affinity of Ras for GDP c. a change that decreases the affiniity of Ras for GTP d. a change that decreases the rate of hydrolysis of GTP by Ras

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Answers (1)

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Donald · Answer 1

d. a change that decreases the rate of hydrolysis of GTP by Ras

Explanation:

When the Ras protein is bound to GTP, it's active and transmits proliferation signals. After some time of sending those signals, the intrinsic GTPase activity of the protein hydrolyzes GTP into GDP. Bound to GDP, the Ras protein is inactive.

The most common mutations in Ras affect the GTPase activity, causing its loss of function and thus decreasing the rate of hydrolisis of GTP. This causes that Ras remains bound to GTP and in its active conformation, permanently sending signals to stimulate cell proliferation.