Q: Which of the following equations correctly represents the formation of cyclic AMP (cAMP) from ATP?

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

Question 1

Which of the following best describes paracrine signaling in animal cells?

Accepted Answer

A cell releases signaling molecules that affect only neighboring cells in the local environment.

Question 2

Which of the following is the correct sequence of the three stages of cell signaling?

Accepted Answer

Reception, transduction, response

Question 3

A researcher discovers a new hormone in plants that is transported through the vascular system to distant tissues. This is an example of which type of signaling?

Accepted Answer

Endocrine signaling

Question 4

Which of the following statements about ligand-receptor interactions is correct?

Accepted Answer

Ligand binding causes a conformational change in the receptor, initiating a signal transduction pathway.

Question 5

Which of the following receptor types is most likely to directly alter gene expression by acting as a transcription factor?

Accepted Answer

Intracellular receptor

Question 6

A pharmaceutical company is designing a drug to block a specific G protein-coupled receptor (GPCR). Which of the following would most likely result from successful inhibition of this receptor?

Accepted Answer

The cell would be unable to initiate the associated signal transduction pathway upon ligand binding.

Question 7

Which of the following best explains how a signal molecule that does NOT enter the cell can still produce a cellular response?

Accepted Answer

The signal molecule binds to a cell-surface receptor, which then triggers a cascade of intracellular events.

Question 8

Which of the following equations correctly represents the formation of cyclic AMP (cAMP) from ATP?

Accepted Answer

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

Question 9

Which of the following best describes the role of protein phosphatases in cell signaling?

Accepted Answer

They remove phosphate groups from proteins, deactivating them.

Question 10

A mutation causes a cell to have abnormally high cytosolic Ca$$^{2+}$$ levels. Which of the following is the most likely direct effect on cell signaling?

Accepted Answer

Increased activation of Ca$$^{2+}-$$dependent signaling pathways

Question 11

Which of the following is a key advantage of signal amplification in a signal transduction pathway?

Accepted Answer

It ensures that only one molecule of ligand is needed to produce a large cellular response.

Question 12

Why might two different cell types respond differently to the same signaling molecule?

Accepted Answer

They express different sets of receptors and intracellular signaling proteins.

Question 13

Which of the following best describes the function of scaffolding proteins in cell signaling?

Accepted Answer

They organize groups of relay proteins to increase the efficiency of signal transduction.

Question 14

A ligand-gated ion channel opens in response to a neurotransmitter. What is the immediate result?

Accepted Answer

Ions flow across the membrane, changing the membrane potential.

Question 15

Which of the following is an example of a second messenger in cell signaling?

Accepted Answer

cAMP

Question 16

A cell receives a signal that leads to the activation of a transcription factor. Where does the final cellular response most likely occur?

Accepted Answer

In the nucleus, by regulating gene expression

Question 17

Which of the following best explains why a single hormone can have different effects in different tissues?

Accepted Answer

Different tissues have different receptors or signal transduction pathways.

Question 18

Which of the following is a correct statement about the location of signal receptors in target cells?

Accepted Answer

Some receptors are located in the cytoplasm or nucleus, especially for hydrophobic ligands.

Question 19

Which of the following best describes how phosphorylation cascades amplify a signal during transduction?

Accepted Answer

Each activated kinase can activate multiple downstream kinases, resulting in a large number of activated proteins.

Question 20

A patient is given a drug that inhibits adenylyl cyclase. What is the most likely effect on the cell's response to a hormone that uses cAMP as a second messenger?

Accepted Answer

The cell's response will be reduced because less cAMP is produced.

Cell Communication: Study Notes for Chapter 11

Study Guide - Practice Questions

Study Guide - Flashcards