Question 1

Which of the following best describes the main function of chemical messengers in cell signaling?

Accepted Answer

They transmit messages between cells by binding to specific receptors and eliciting a response.

Question 2

A patient is diagnosed with a disease caused by a mutation in a gene encoding a chloride ion channel. Which of the following diseases is most likely?

Accepted Answer

Cystic fibrosis

Question 3

Which of the following statements about drug-receptor interactions is CORRECT?

Accepted Answer

Drug + receptor $$ \rightleftharpoons $$ drug:receptor complex $$ \rightarrow $$ biologic effect

Question 4

Which of the following is a second messenger generated in response to the binding of a first messenger to a plasma membrane receptor?

Accepted Answer

3,5-cyclic AMP (cAMP)

Question 5

Which type of receptor is most directly involved in the rapid regulation of ion flow across the cell membrane in response to neurotransmitter binding?

Accepted Answer

Ligand-gated ion channel receptors

Question 6

A hormone is secreted into the bloodstream and acts on distant target cells. This type of signaling is best described as:

Accepted Answer

Endocrine

Question 7

Which of the following is TRUE regarding the insulin receptor?

Accepted Answer

It exists as a dimer in the membrane and is a member of the tyrosine kinase family.

Question 8

Which of the following best explains why failure to terminate a chemical signal can lead to disease?

Accepted Answer

Persistent signaling can result in uncontrolled cell growth, contributing to diseases such as cancer.

Question 9

Which of the following is a characteristic of enzyme-linked receptors?

Accepted Answer

They contain intrinsic enzyme activity or associate with intracellular enzymes.

Question 10

A mutation in the gene encoding a sodium ion channel is most likely to affect which physiological process?

Accepted Answer

Muscle contraction

Question 11

Which of the following best describes the mechanism of action for receptor tyrosine kinases (RTKs)?

Accepted Answer

Ligand binding causes dimerization and autophosphorylation of tyrosine residues.

Question 12

Which of the following is a correct pairing of receptor type and its example?

Accepted Answer

Enzyme-linked receptor: Epidermal growth factor receptor (EGFR)

Question 13

Which of the following statements about JAK-STAT receptors is CORRECT?

Accepted Answer

They are used by cytokines and have a more direct route for signal propagation to the nucleus than other tyrosine kinase receptors.

Question 14

Which of the following is NOT a second messenger?

Accepted Answer

Epidermal growth factor (EGF)

Question 15

A signaling molecule binds to a receptor in the cytoplasm, which then directly regulates gene transcription. This receptor is most likely:

Accepted Answer

An intracellular receptor

Question 16

Which of the following best describes paracrine signaling?

Accepted Answer

A cell releases a signal that acts on nearby cells.

Question 17

Which of the following is a common feature of all four major receptor families (ligand-gated ion channels, G-protein coupled receptors, enzyme-linked receptors, and intracellular receptors)?

Accepted Answer

They all require ligand binding to initiate a cellular response.

Question 18

Which of the following is a possible consequence of a failure in signal termination in cell signaling pathways?

Accepted Answer

Increased risk of cancer due to prolonged signaling.

Question 19

Which of the following best explains why ion channel receptors are important in the nervous system?

Accepted Answer

They allow rapid and transient changes in membrane potential necessary for nerve impulse transmission.

Question 20

A researcher discovers a new receptor that, upon ligand binding, activates an intracellular enzyme without intrinsic enzyme activity. This receptor is best classified as:

Accepted Answer

An enzyme-linked receptor

Signaling Mechanisms and Drug Action: Biochemical Principles

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