Question 1

Which of the following is a secondary messenger produced in the Phosphoinositide Signaling Pathway (PSP) after activation of Phospholipase C?

Accepted Answer

Inositol trisphosphate (IP3)

Question 2

What is the primary function of Protein Kinase C (PKC) in the PSP pathway?

Accepted Answer

Phosphorylating target proteins to propagate the signal

Question 3

Which equation correctly represents the hydrolysis of PIP2 by Phospholipase C?

Accepted Answer

$$\mathrm{$$PIP_2$$} \xrightarrow{PLC} \mathrm{IP_3$} + \mathrm{DAG}$$

Question 4

Upon activation of the GPCR in the PSP pathway, which G-protein subunit exchanges GDP for GTP?

Accepted Answer

Alpha subunit

Question 5

Which of the following steps occurs FIRST in the PSP signaling pathway?

Accepted Answer

Ligand binds to GPCR

Question 6

What is the role of IP$$_3 in $$the PSP pathway?

Accepted Answer

Triggers the release of Ca$$^{2+}$$ from the endoplasmic reticulum

Question 7

Which of the following is NOT a direct product of Phospholipase C activity?

Accepted Answer

Calcium ions (Ca$$^{2+})$$

Question 8

Which of the following statements about G-protein activation in the PSP pathway is INCORRECT?

Accepted Answer

Beta and gamma subunits directly activate Phospholipase C

Question 9

Which of the following molecules directly activates Protein Kinase C (PKC) in the PSP pathway?

Accepted Answer

Diacylglycerol (DAG)

Question 10

A mutation prevents the hydrolysis of GTP to GDP in the alpha subunit of a G-protein. What is the most likely consequence?

Accepted Answer

Prolonged activation of downstream signaling

Question 11

Which of the following is a correct sequence of events in the PSP pathway?

Accepted Answer

Ligand binds GPCR → G-protein activation → PLC activation → PIP$$_2$$ hydrolysis → IP$$_3$$ and DAG production

Question 12

Which of the following is NOT required for the activation of Phospholipase C in the PSP pathway?

Accepted Answer

cAMP production

Question 13

Which of the following is a common misconception about the PSP pathway?

Accepted Answer

cAMP is produced by Phospholipase C

Question 14

Which of the following is TRUE regarding the role of calcium ions (Ca$$^{2+}) in $$the PSP pathway?

Accepted Answer

Ca$$^{2+} is $$released from the endoplasmic reticulum into the cytoplasm

Question 15

Which of the following is NOT a substrate for the reaction catalyzed by Phospholipase C?

Accepted Answer

Diacylglycerol (DAG)

Question 16

Which of the following steps is necessary for the termination of the PSP signaling pathway?

Accepted Answer

Hydrolysis of GTP to GDP by the alpha subunit

Question 17

Which of the following is a direct effect of increased cytoplasmic Ca$$^{2+}$$ concentration in the PSP pathway?

Accepted Answer

Activation of calmodulin-binding proteins

Question 18

Which of the following is NOT a function of the PSP pathway?

Accepted Answer

Synthesis of DNA

Question 19

Which of the following statements about the PSP pathway is CORRECT?

Accepted Answer

Phospholipase C hydrolyzes PIP$$_2 to $$produce IP$$_3$$ and DAG

Phosphoinositide GPCR Signaling Pathway: Mechanisms and Secondary Messengers

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