Q: Which equation correctly represents the conversion of ATP to cAMP by adenylyl cyclase?

$$\mathrm{ATP} \xrightarrow{\text{adenylyl cyclase}} \mathrm{cAMP} + \mathrm{PP_i}$$

Question 1

Which type of cell signaling involves signaling molecules traveling through the bloodstream to reach distant target cells?

Accepted Answer

Endocrine signaling

Question 2

A researcher uses optogenetics to activate neurons in a rat's brain by shining blue light through an implanted fiber optic cable. Which stage of cell signaling is directly manipulated in this experiment?

Accepted Answer

Reception

Question 3

Which of the following is a key difference between G-protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs)?

Accepted Answer

RTKs phosphorylate themselves and other proteins upon ligand binding

Question 4

Which of the following molecules acts as a second messenger in the epinephrine signaling pathway?

Accepted Answer

cAMP

Question 5

A mutation disables the function of a protein required for ant odor detection. What is the most likely behavioral consequence?

Accepted Answer

Mutant ants would never follow trails

Question 6

Which of the following is LEAST likely to cause denaturation of a protein?

Accepted Answer

Exposure to a more hypotonic environment

Question 7

What is the function of phosphatases in cell signaling?

Accepted Answer

They remove phosphate groups from proteins

Question 8

Which equation correctly represents the conversion of ATP to cAMP by adenylyl cyclase?

Accepted Answer

$$\mathrm{ATP} \xrightarrow{	ext{adenylyl cyclase}} \mathrm{cAMP} + \mathrm{PP_i}$$

Question 9

A patient does not respond to human growth hormone injections and has no detectable hormone in the blood. Which cell signaling component is most likely defective?

Accepted Answer

The hormone receptor

Question 10

Which of the following best describes the role of scaffold proteins in cell signaling?

Accepted Answer

They organize and localize signaling components to increase efficiency

Question 11

Which of the following is a real-world example of local signaling?

Accepted Answer

Neurotransmitters released at a synapse between two neurons

Question 12

Which of the following statements about ligand binding to receptors is TRUE?

Accepted Answer

Ligand binding is typically specific and reversible

Question 13

What is the most likely consequence of high concentrations of cAMP in a cell?

Accepted Answer

Increase in the rate of glycogen metabolism

Question 14

Which of the following best explains why epinephrine added to isolated glycogen phosphorylase does NOT result in glucose production?

Accepted Answer

Epinephrine cannot bind to glycogen phosphorylase directly

Question 15

Which of the following is a function of kinases in cell signaling?

Accepted Answer

Kinases add phosphate groups to proteins using ATP

Question 16

Which type of receptor is most likely to be activated by steroid hormones?

Accepted Answer

Intracellular nuclear hormone receptor

Question 17

Which of the following best describes the amplification step in a cell signaling pathway?

Accepted Answer

A single ligand binding event leads to the activation of many downstream molecules

Question 18

Which equation represents the phosphorylation of a protein by a kinase?

Accepted Answer

$$	ext{Protein} + 	ext{ATP} \xrightarrow{	ext{kinase}} 	ext{Protein-P} + 	ext{ADP}$$

Question 19

Which of the following is a plausible effect of blocking G-protein activation in a cell?

Accepted Answer

Decreased cellular response to extracellular signals

Question 20

Which of the following best describes juxtacrine signaling?

Accepted Answer

Cells communicate by direct physical contact through membrane-bound proteins

Cell Signaling in General Biology: Mechanisms, Molecules, and Pathways

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