Question 1

Which of the following best describes the three stages of cell signaling as illustrated in the first image?

Accepted Answer

Signal reception, signal transduction, cellular response

Question 2

A signaling molecule binds to a receptor on the cell surface, causing a cascade of events that ultimately leads to the breakdown of glycogen and release of glucose. Which molecule acts as the first messenger in this pathway?

Accepted Answer

Epinephrine

Question 3

Refer to the second image. What structural feature is characteristic of G protein-coupled receptors (GPCRs)?

Accepted Answer

Seven transmembrane α helices

Question 4

In the third image, what is the role of GDP in the G protein signaling pathway?

Accepted Answer

GDP binds to the inactive G protein, keeping it inactive until a signal is received

Question 5

What event is depicted in the fourth image, where the signaling molecule binds to the receptor?

Accepted Answer

The receptor changes shape and activates the G protein by exchanging GDP for GTP

Question 6

In the fifth image, what is the immediate result of the activated G protein interacting with the enzyme?

Accepted Answer

The enzyme is activated, leading to a cellular response

Question 7

How is the G protein signaling pathway terminated, as shown in the sixth image?

Accepted Answer

The G protein hydrolyzes GTP to GDP, inactivating itself

Question 8

What is the primary function of receptor tyrosine kinases (RTKs) as shown in the seventh and eighth images?

Accepted Answer

They dimerize and autophosphorylate upon ligand binding, activating multiple signaling pathways

Question 9

Which of the following best explains why RTKs can trigger multiple cellular responses simultaneously?

Accepted Answer

Each phosphorylated tyrosine on the dimerized RTK can bind a different relay protein, activating multiple pathways

Question 10

Which of the following equations correctly represents the phosphorylation reaction catalyzed by a kinase?

Accepted Answer

$$\mathrm{Protein} + \mathrm{ATP} \rightarrow \mathrm{Protein{-}P} + \mathrm{ADP}$$

Question 11

Which of the following is a key advantage of multistep signal transduction pathways?

Accepted Answer

They allow for signal amplification and precise regulation

Question 12

Which of the following best describes the role of second messengers in cell signaling?

Accepted Answer

They are small, nonprotein molecules that relay signals inside the cell

Question 13

Which of the following is a common second messenger in G protein-coupled receptor pathways?

Accepted Answer

cAMP

Question 14

What is the effect of cholera toxin on G protein signaling?

Accepted Answer

It locks the G protein in its active state, causing continuous cAMP production

Question 15

Which of the following is NOT a typical cellular response induced by calcium ions as second messengers?

Accepted Answer

DNA replication

Question 16

Why do only certain cells respond to a specific hormone like aldosterone?

Accepted Answer

Only those cells have the specific intracellular receptor for the hormone

Question 17

Which of the following best describes the function of transcription factors in cell signaling?

Accepted Answer

They regulate which genes are transcribed into mRNA

Question 18

Which of the following is a way that cell signaling can be terminated?

Accepted Answer

Enzymatic degradation of the signaling molecule

Question 19

Which of the following best describes apoptosis?

Accepted Answer

A programmed cell death process involving DNA fragmentation and cell shrinkage

Question 20

Which of the following is an example of a signal that can trigger apoptosis from inside the cell?

Accepted Answer

DNA damage

Cell Communication: Signal Transduction Pathways and Cellular Responses

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