Q: Which of the following equations correctly represents the conversion of ATP to cyclic AMP (cAMP) by adenylyl cyclase?

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

Question 1

Which of the following best describes quorum sensing in bacteria?

Accepted Answer

A process where bacteria sense and respond to population density by producing and detecting signaling molecules.

Question 2

Which type of cell signaling involves the release of neurotransmitters in response to an electrical signal?

Accepted Answer

Synaptic signaling

Question 3

A researcher discovers a new hormone that is hydrophobic and can cross the plasma membrane. Which type of receptor is this hormone most likely to bind?

Accepted Answer

An intracellular receptor

Question 4

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

Accepted Answer

Reception → Transduction → Response

Question 5

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 collections of proteins and signaling pathways.

Question 6

Which of the following is TRUE about G protein-coupled receptors (GPCRs)?

Accepted Answer

They are the largest family of cell-surface receptors and work with the help of G proteins that bind GTP.

Question 7

A mutation causes a receptor tyrosine kinase (RTK) to be permanently active. What is a likely consequence?

Accepted Answer

Uncontrolled cell division, potentially leading to cancer

Question 8

Which of the following equations correctly represents the conversion of ATP to cyclic AMP (cAMP) by adenylyl cyclase?

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 kinases in a phosphorylation cascade?

Accepted Answer

They transfer phosphate groups from ATP to proteins, activating or deactivating them.

Question 10

A patient is exposed to the cholera toxin, which causes a G protein to be stuck in its active form. What is the direct cellular consequence?

Accepted Answer

Continuous production of cAMP, leading to excessive ion and water loss from cells

Question 11

Which of the following is a common second messenger in signal transduction pathways?

Accepted Answer

Cyclic AMP (cAMP)

Question 12

Which of the following statements about apoptosis is correct?

Accepted Answer

It is a programmed cell death process that prevents damage to neighboring cells.

Question 13

Which protein acts as a 'brake' on apoptosis in Caenorhabditis elegans?

Accepted Answer

Ced-9

Question 14

Which of the following best explains why calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$can function as a second messenger?

Accepted Answer

Their cytosolic concentration is normally much lower than outside the cell, so small changes have large effects.

Question 15

Which of the following is a function of scaffolding proteins in signal transduction?

Accepted Answer

They increase the efficiency of signal transduction by grouping together relay proteins.

Question 16

A mutation prevents protein phosphatases from functioning in a cell. What is the most likely effect?

Accepted Answer

Proteins will remain phosphorylated, and signaling pathways may remain active longer than normal.

Question 17

Which of the following is an example of a cytoplasmic response to a signal?

Accepted Answer

Activation of an enzyme that breaks down glycogen in response to epinephrine

Question 18

Which of the following equations represents the removal of a phosphate group from a protein by a phosphatase?

Accepted Answer

$$	ext{Protein-}P \xrightarrow{	ext{phosphatase}} 	ext{Protein} + P_i$$

Question 19

Which of the following is a real-life example of the importance of cell signaling in medicine?

Accepted Answer

Interfering with bacterial quorum sensing to prevent biofilm formation and antibiotic resistance

Cell Communication: Mechanisms and Pathways (Campbell Biology, Ch. 11)

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