Question 20 (2 points): Which statement about heterotrimeric G proteins is NOT t

Question

Question 20 (2 points): Which statement about heterotrimeric G proteins is NOT true? A. G proteins are activated by the binding of a ligand to a membrane receptor. B. G proteins are integral membrane proteins. C. G proteins are inactive when bound to GDP and active when bound to GTP D. When activated, G proteins stimulate production of a second messenger inside the cell. E. G proteins self-inactivate by slowly hydrolyzing GTP to GDP. Question 21 (2 points): Which of the following is NOT a feature common to biological signaling systems? A. A signal received by the cell is amplified by multiple enzyme molecules. B. Components of the system can be reversibly activated and deactivated. C. A single receptor can bind multiple types of signaling molecules. D. Receptor activation initiates a feedback circuit that eventually terminates signaling. E. Integrated input from multiple receptors determines the net effect on a cell.

Explanation / Answer

Question: 20

Which of the statement about heterotrimeric G protein is not true?

G proteins are Guanine nucleotide binding proteins. These proteins are the membrane associated protein.

Answer: E. G proteins self-inactivate by slowly hydrolysing GTP to GDP.

Question: 21

Which of the following is not a feature common to biological signalling system?

Answer: A single receptor can bind multiple types of signalling molecules.

Receptors are very specific for its signalling molecules the ligands. When these receptors are bound to its specific ligand it cause the conformational change that activates the pathways associated with it.

Conformation plays a vital role in the function of the receptors. Thus specificity is much important.

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