Question 1

A drug that binds to a receptor and directly initiates a change in the function of the cell is referred to as&#10;A) an agonist&#10;B) an antagonist&#10;C) a synergist&#10;D) a compliment

Accepted Answer

An agonist is a drug that binds to a receptor and directly initiates a change in the function of the cell. This is in contrast to an antagonist, which blocks the action of an agonist, and a synergist, which enhances the action of an agonist, but does not initiate the change directly. A compliment is not relevant to this context.

Question 2

The primary location for receptors that recognize drugs and endogenous compounds is&#10;A) on the surface of the cell&#10;B) in the cytoplasm of the cell&#10;C) on the cell's nuclear membrane&#10;D) on the cell's chromosomes&#10;E) on the ribosomes

Accepted Answer

The primary location for receptors that recognize drugs and endogenous compounds is on the surface of the cell. This is because these receptors need to be able to interact with molecules that are present in the extracellular space, such as neurotransmitters and hormones. Once a ligand binds to a receptor on the surface of the cell, it can initiate a signaling cascade that ultimately leads to a cellular response. Receptors can also be found inside the cell, such as in the cytoplasm or on the nucleus, but these are typically involved in specialized functions and are not the primary targets for most drugs.

Question 3

Some drugs affect the function of the adenylate cyclase,an enzyme located on the inner surface of the cell membrane.This enzyme is responsible for hydrolyzing adenosine triphosphate (ATP)into _____,which acts as a second messenger that activates other enzymes (i.e.,protein kinases)throughout the cell.

A) adenosine diphosphate (ADP)
B) cyclic adenosine monophosphate (cAMP)
C) acetylcholine
D) norepinephrine
E) adrenaline

cyclic adenosine monophosphate (cAMP)

Accepted Answer

Adenylate cyclase is responsible for converting ATP to cyclic adenosine monophosphate (cAMP), which acts as a second messenger in the cell to activate other enzymes. Therefore, the correct answer is choice B. Choices C, D, and E are neurotransmitters and not directly related to the function of adenylate cyclase. Choice A refers to the hydrolysis of ATP to ADP, which is a precursor to ATP production but not directly related to the function of adenylate cyclase.

Question 4

A drug that fails to evoke a maximal response even though it occupies all available receptors is known as&#10;A) a competitive antagonist&#10;B) a noncompetitive antagonist&#10;C) a partial agonist&#10;D) a competitive agonist&#10;E) an inverse antagonist

Accepted Answer

A drug that fails to evoke a maximal response even though it occupies all available receptors is known as a partial agonist. A competitive antagonist would compete with an agonist for the same binding site and reduce the effect of the agonist. A noncompetitive antagonist would bind irreversibly to the receptor and prevent activation by any agonist. A competitive agonist would bind to the same site as the agonist but produce less of an effect. An inverse agonist would produce the opposite effect of an agonist at the same receptor.

Question 5

In contrast to an agonist,a pharmacologic antagonist&#10;A) has affinity for the receptor, but lacks efficacy&#10;B) is also known as a &#34;blocker&#34;&#10;C) can be used prevent endogenous chemicals from overstimulating the receptor&#10;D) all the above are true&#10;E) none of the above are true

Accepted Answer

A pharmacologic antagonist has affinity for the receptor, but lacks efficacy and is known as a "blocker". It can be used to prevent endogenous chemicals from overstimulating the receptor. Therefore, all the above choices are true.

Question 6

The ability of a drug to bind to its receptor can be influenced by local chemicals such as guanine nucleotides,ammonium ions,and divalent cations.These local regulators are commonly known as _____.&#10;A) competitive agonists&#10;B) noncompetitive agonists&#10;C) allosteric modulators&#10;D) partial antagonists&#10;E) chelators

Accepted Answer

Allosteric modulators are local chemicals that influence the binding of a drug to its receptor by binding to a regulatory site on the receptor, rather than the binding site itself. Competitive agonists (A) and noncompetitive agonists (B) bind to the same site as the endogenous ligand or receptor, while partial antagonists (D) bind to the same site as an agonist but do not produce a maximal response. Chelators (E) are compounds that bind to metal ions to form a complex, but they do not directly influence the binding of drugs to receptors.

Question 7

A noncompetitive antagonist&#10;A) has a more or less equal opportunity to occupy the receptor as the agonist&#10;B) forms rather weak bonds with the receptor&#10;C) produces inhibition that can be overcome by administering high concentrations of the agonist&#10;D) all of the above are true&#10;E) none of the above are true

Accepted Answer

A noncompetitive antagonist binds to a site other than the agonist binding site (allosteric site) or irreversibly binds to the receptor, making its inhibition not overcome by simply increasing the concentration of the agonist. Therefore, options A, B, and C do not accurately describe noncompetitive antagonists.

Question 8

Signals from the surface receptor are transduced into the appropriate response within the cell via intermediate regulatory proteins that are activated by binding guanine nucleotides,hence they are often termed ______ proteins.

A) activating
B) binding
C) controlling
D) nucleotide
E) G

Accepted Answer

The question specifically mentions "guanine nucleotides" which are a key feature of G proteins. Therefore, the best choice is E, as G proteins are activated by binding guanine nucleotides and are commonly known as G proteins.

Question 9

Overstimulation of postsynaptic receptors may lead to a decrease in responsiveness of the receptors.A fairly brief and transient decrease in receptor responsiveness is known as _____,whereas a more prolonged process in which the actual number of available receptors is diminished is known as _________.

A) down-regulation; desensitization
B) desensitization; up-regulation
C) up-regulation; desensitization
D) down-regulation; autophosphorylation
E) desensitization; down-regulation

Accepted Answer

Desensitization refers to a brief and transient decrease in receptor responsiveness, while down-regulation involves a more prolonged process where the number of available receptors is diminished.

Question 10

The acetylcholine receptor located on the postsynaptic membrane of the skeletal neuromuscular junction is an example of a membrane receptor that&#10;A) is linked directly to an intracellular enzyme&#10;B) is linked directly to a regulatory G protein&#10;C) functions as an ion channel or pore&#10;D) moves (translocates) to the cell's nucleus when stimulated&#10;E) none of the above are true

Accepted Answer

The acetylcholine receptor located on the postsynaptic membrane of the skeletal neuromuscular junction functions as an ion channel or pore, allowing the passage of ions such as Na+ and K+. It is not linked directly to an intracellular enzyme or regulatory G protein, nor does it translocate to the cell's nucleus when stimulated.

Question 11

A drug that binds readily to available receptors even if the concentration of drug is relatively low is said to have _______ for that receptor.&#10;A) low specificity&#10;B) high affinity&#10;C) a short half-life&#10;D) all the above are true&#10;E) none of the above are true

Accepted Answer

The answer of A drug that binds readily to available...

Deck 4: Drug Receptors