Changes to Signal Transduction

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Which of the following outcomes will most likely result from the irreversible binding of GDP

GDP to the G protein?

• The intracellular concentration of glycogen will increase.

• The intracellular concentration of activated protein kinase A will increase.

• The intracellular concentration of cyclic AMP

  AMP will increase.

• The intracellular concentration of glucose-1-phosphate will increase.

Tags

NGSS.HS-LS1-3

Cyclic AMP phosphodiesterase is an enzyme that catalyzes the conversion of cyclic AMP to a different molecule. Which of the following best predicts the effect of inhibiting cyclic AMP phosphodiesterase in a muscle cell stimulated by epinephrine?

• The concentration of cyclic AMP

  AMP will decrease because adenylyl cyclase will no longer be activated.

• The G protein will diffuse out of the cell because it will no longer bind to the plasma membrane.

• Phosphorylase kinase will remain active because protein kinase A will no longer be deactivated.

• Glycolysis will stop because epinephrine signaling will no longer stimulate glycogen breakdown.

Tags

NGSS.HS-LS1-3

Glucocorticoids are steroid hormones that control cellular responses through several different signaling pathways. One of the signaling pathways involves the glucocorticoid receptor, an intracellular protein that is activated by binding to a glucocorticoid molecule. A simplified model of the glucocorticoid receptor signaling pathway is represented in Figure 1. Which of the following statements best predicts the effect of a mutation that results in a loss of the glucocorticoid receptor’s ligand binding function?

• The transduction of the glucocorticoid signal across the plasma membrane will be blocked.

• The glucocorticoid receptor will remain associated with the accessory proteins.

• The rate of diffusion of glucocorticoid molecules into the cell will increase.

• The concentration of glucocorticoid receptors inside the nucleus will increase.

Tags

NGSS.HS-LS1-3

A DNA mutation changes the shape of the extracellular domain of transmembrane receptor protein A produced by the cell. Which of the following predictions is the most likely consequence of the mutation?

• Production of activated molecule 1 will stop, but production of activated molecules 2 and 3 will continue.

• The molecule that normally binds to protein A will no longer attach, deactivating the cellular response

• The molecule that normally binds to protein A will not enter the cell, thus no cellular response will occur.

• Since protein A is embedded in the membrane, the mutation will be silent and not affect the cellular response.

Tags

NGSS.HS-LS1-1

Air is less dense at very high elevations, so less oxygen is available than in the denser air at sea level. Based on the model in Figure 1, if a person travels from sea level to a high elevation location, which of the following correctly predicts the response to the decreased blood oxygen level?

• More erythropoietin will be secreted from the kidneys, decreasing production of erythrocytes.

• Less erythropoietin will be secreted from the kidneys, decreasing production of erythrocytes.

• More erythropoietin will be secreted from the kidneys, increasing production of erythrocytes.

• Less erythropoietin will be secreted from the kidneys, increasing production of erythrocytes.

Tags

NGSS.HS-LS1-3

Argatroban is a competitive inhibitor of thrombin. Which of the following effects on the coagulation cascade is most likely to result from inhibiting thrombin activity with argatroban?

• The rate of fibrin formation will decrease.

• The activation of clotting factors will be blocked.

• Thrombin will be converted to prothrombin.

• The rate of blood clot formation will increase.