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

Question 1

Which of the following best describes the three stages of cell signaling?

Accepted Answer

Reception, transduction, and response

Question 2

A researcher adds epinephrine and glycogen phosphorylase to a test tube but observes no glucose production. What is the most likely explanation?

Accepted Answer

An intact cell is required for the signal transduction pathway to occur

Question 3

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

Accepted Answer

Intracellular receptor

Question 4

What is the primary function of protein kinases in signal transduction pathways?

Accepted Answer

Transfer phosphate groups to proteins

Question 5

Which of the following is a correct sequence of events in the epinephrine signaling pathway leading to glycogen breakdown?

Accepted Answer

Epinephrine binds to GPCR → G protein activates adenylyl cyclase → cAMP produced → Protein kinase A activated

Question 6

Which of the following best explains why the same signaling molecule can produce different responses in different cell types?

Accepted Answer

Different cells have different proteins and pathways activated by the same signal

Question 7

A mutation causes a G protein to remain constantly active. Which disease is most closely associated with this malfunction?

Accepted Answer

Cholera

Question 8

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

Accepted Answer

cAMP

Question 9

What is the role of scaffolding proteins in cell signaling?

Accepted Answer

They organize and hold together multiple relay proteins to increase signaling efficiency

Question 10

Which of the following best describes quorum sensing in bacteria?

Accepted Answer

A process where bacteria sense local cell density and coordinate activity

Question 11

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 12

Which of the following is a real-life example of paracrine signaling?

Accepted Answer

Growth factors released by one cell stimulate nearby cells to divide

Question 13

What is the main function of receptor tyrosine kinases (RTKs)?

Accepted Answer

They phosphorylate tyrosine residues on themselves and other proteins, activating multiple signaling pathways

Question 14

Which of the following best explains why HER2 is a target in breast cancer therapy?

Accepted Answer

HER2 is a receptor tyrosine kinase that, when overexpressed, leads to excessive cell division

Question 15

Which of the following is a correct statement about apoptosis?

Accepted Answer

It is a programmed cell death process regulated by signaling pathways

Question 16

Which of the following best describes the role of calcium ions ($$\mathrm{Ca$$^{2+}$$}) in $$cell signaling?

Accepted Answer

They act as second messengers, triggering responses such as muscle contraction and secretion

Question 17

A mutation in the gene encoding protein phosphatase would most likely result in which of the following?

Accepted Answer

Prolonged activation of signaling pathways due to failure to remove phosphate groups

Question 18

Which of the following is an example of direct cell-to-cell communication in animals?

Accepted Answer

Gap junctions allowing ions and small molecules to pass between adjacent cells

Question 19

Which of the following best explains the amplification of a signal in a phosphorylation cascade?

Accepted Answer

Each activated enzyme in the cascade can activate many molecules of the next enzyme

Question 20

Which of the following scenarios best illustrates the concept of specificity in cell signaling?

Accepted Answer

Epinephrine causes liver cells to break down glycogen but causes heart cells to increase heartbeat

Cell Communication: Mechanisms and Pathways chpt.11

Study Guide - Practice Questions