AP BIOLOGY

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THE CELL

CELL COMMUNICATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Ras, a small G protein located at the plasma membrane, is often mutated in different types of cancer. Ras normally signals to a cell that it should divide. Cancer cells divide uncontrollably. Which of the following changes to Ras would you expect to see in a cancer cell that has mutated Ras present?
A
a mutation that means Ras cannot hydrolyze GTP to GDP
B
a mutation that leads to Ras being sent to the endomembrane system
C
a mutation that means Ras cannot bind to GTP
D
a mutation that means GDP is constantly bound to Ras
E
a mutation in which Ras cannot bind to its GPCR
Explanation: 

Detailed explanation-1: -Ras, a small G protein located at the plasma membrane, is often mutated in different types of cancer. Ras normally signals to a cell that it should divide. Cancer cells divide uncontrollably.

Detailed explanation-2: -Each small G protein is localized to a specific membrane. Ras proteins are localized at the cytoplasmic face of the plasma membrane. This localization is mediated by the posttranslational modifications with lipid.

Detailed explanation-3: -Answer and Explanation: The correct answer is a. They mediate the action of fast acting neurotransmitters.

Detailed explanation-4: -All GPCRs share a similar structure, which includes seven transmembrane domains, an extracellular amino terminal, an intracellular carboxyl terminal, three extracellular loops, and three cytosolic loops (Fig. 2.4).

There is 1 question to complete.
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