Question 1

Which of the following is the correct order of events in the insulin signaling pathway leading to increased glucose uptake?

Accepted Answer

Activation of insulin receptor → Phosphorylation of IRS-1 → Activation of PI3K → Production of PIP3 → Activation of PKB → GLUT4 translocation

Question 2

What is the primary role of PKB (also known as Akt) in the insulin signaling pathway?

Accepted Answer

PKB promotes translocation of GLUT4 vesicles to the plasma membrane, increasing glucose uptake.

Question 3

Which molecule is directly responsible for converting PIP2 to PIP3 in the insulin signaling pathway?

Accepted Answer

PI3K

Question 4

If the PKB gene is deleted in insulin-responsive cells, which of the following would most likely be observed?

Accepted Answer

GLUT4 vesicles would remain in intracellular vesicles and not translocate to the membrane.

Question 5

Which of the following is NOT a direct result of insulin signaling in muscle cells?

Accepted Answer

Hydrolysis of ATP by PI3K

Question 6

What would be the effect of a mutation that prevents phosphorylation of IRS-1 in the insulin signaling pathway?

Accepted Answer

PI3K would not be recruited to the membrane, impairing downstream signaling.

Question 7

Which enzyme catalyzes the phosphorylation of PIP2 to PIP3?

Accepted Answer

PI3K

Question 8

In the context of insulin signaling, what is the function of GLUT4?

Accepted Answer

GLUT4 is a transporter that facilitates glucose entry into the cell.

Question 9

Which of the following would most likely occur if IRS-1 is overexpressed in muscle cells?

Accepted Answer

Protein kinase B would be overactivated, resulting in increased glycogen synthesis.

Question 10

Which of the following is NOT a function of PI3K in the insulin signaling pathway?

Accepted Answer

Phosphorylation of IRS-1

Question 11

What is the effect of insulin on glycogen synthase in muscle cells?

Accepted Answer

Insulin activates glycogen synthase by promoting its dephosphorylation.

Question 12

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

Accepted Answer

Activation of the insulin receptor

Question 13

A patient with a mutation in the PI3K gene is likely to experience which of the following symptoms?

Accepted Answer

Reduced glucose uptake due to impaired GLUT4 translocation

Question 14

Which of the following is a product of the reaction catalyzed by PI3K?

Accepted Answer

$$\mathrm{PIP}_3$$

Question 15

What would be the consequence of a mutation that prevents activation of the insulin receptor?

Accepted Answer

IRS-1 would not be phosphorylated, blocking downstream signaling.

Question 16

Which of the following is TRUE regarding the role of PDK1 in insulin signaling?

Accepted Answer

PDK1 phosphorylates and activates PKB.

Question 17

In the insulin signaling pathway, which molecule acts as a docking site for PDK1 and PKB?

Accepted Answer

$$\mathrm{PIP}_3$$

Question 18

Which of the following would most likely result from a loss-of-function mutation in IRS-1?

Accepted Answer

Decreased activation of PI3K and impaired glucose uptake

Question 19

Which of the following is NOT a direct effect of PKB activation in the insulin signaling pathway?

Accepted Answer

Phosphorylation of IRS-1

Question 20

Which of the following statements about insulin signaling is CORRECT?

Accepted Answer

Insulin signaling leads to increased glucose uptake and glycogen synthesis in muscle cells.

Insulin Signaling and Glucose Metabolism

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