Chemistry Exam: Hardest Trivia Quiz To Take!

1.

Acetylcholinesterase is responsible for

A.

Synthesis of choline
B.

Hydrolysis of ACh
C.

Acetylation of Choline

Correct Answer
B. Hydrolysis of ACh

2.

To which of the following classes of pharmacological receptors do nicotinic receptors belong?

A.

1-transmembrane protiens (enzyme associated)
B.

G-protien coupled
C.

Ion Channel
D.

Transcriptional regulators

Correct Answer
C. Ion Channel

3.

The rate limiting stop in the hydrolysis of Ach is

A.

Hydrolysis of the acetylated enzyme
B.

Diffusion of choline from the active site
C.

Formation of the acetylated enzyme
D.

Binding of ACh to the enzyme to form the transition state

Correct Answer
C. Formation of the acetylated enzyme

4.

Which of the following modifications of Ach results in a potent agonist with muscarinic and nicotinic activity?

A.

Increase the ethylene bridge by one atom
B.

Addition of beta methyl on ethylene bridge
C.

Replacement of one N-mehtyl with N-ethyl
D.

Replacement of the ester with carbamate
E.

Addition of alpha methyl on ethylene bridge

Correct Answer
D. Replacement of the ester with carbamate

Explanation
A. increase in chain length = activity rapidly decreases.

B. B-methyl:increases muscarinic activity>nicotinic activity

C. replacement of a methyl with ethyl or propyl: active but much less than ACh

D. CARBAMATES ARE POTENT AGONISTS FOR BOTH MUSCARINIC AND NICOTINIC RECEPTORS!!!

E. a-methyl reduces both muscarinic and nicotinic activity.

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5.

Which of the following modification of Ach results in a selective agonist on muscarinic recpetors?

A.

Replacement of one N-methyl with N-ethyl
B.

Replacement of the esters with a carbamate
C.

Addition of alpha methyl on ethylene bridge
D.

Increase the ethylene bridge by one atom
E.

Addition of beta methyl on ethylene bridge

Correct Answer
E. Addition of beta methyl on ethylene bridge

Explanation
A. Replacing a methyl with an ethyl of propyl: Active, but much less then ACh

B. Carbamates are potent agonists for both muscarinic and nicotinic receptors

c. A-methyl will decrease both muscarinic and nicotinic activity.

D. increase in ethylene bridge decreaes activity rapidly.

E. Beta methyl increases muscarinic activity more so than nicotinic.

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6.

Which of the following is the rate-limiting substrate in the synthesis of Ach?

A.

Choline
B.

Serine
C.

S-adenosyl methione
D.

Acetyl-S-CoA

Correct Answer
A. Choline

7.

Choline acetyletransferase is responsible for

A.

Hydrolysis of ACh
B.

Synthesis of ACh
C.

Synthesis of choline

Correct Answer
B. Synthesis of ACh

8.

Malathione is considered to have selective toxicity to insects compared to humans. The increased toxicity to insects is due to their inability to metabolize it by:

A.

Oxidation (replace S with O)
B.

Hydrolysis with phosphatases
C.

Hydrolysis of esters

Correct Answer
C. Hydrolysis of esters

9.

Malathione is considered to have selective toxicity to insects compared to humans. The decreased toxicity in humans is due to:

A.

Phosphatase (hydrolyze P-S bond)
B.

Oxidation (replace S with O)
C.

Carboxyesterase (hydrolyze ester)

Correct Answer
C. Carboxyesterase (hydrolyze ester)

10.

Sarin is a chemical warfare agent. The major concern with its use is:

A.

Only one aging reaction occurs before AChE becomes completely refractory to reactivation.
B.

AChE cannot be reactivated with pralidoxime
C.

It is more lipophilic than other agents so more topical absorption occurs

Correct Answer
A. Only one aging reaction occurs before AChE becomes completely refractory to reactivation.

Explanation
Only one aging reaction takes place until enzyme becomes completely refractory to regeneration by currently available antidotal agents.

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11.

Which of the following compounds used in the treatment of Alzheimer’s disease is not a AChEI?

A.

Donepezil
B.

Galantamine
C.

Memantine
D.

Rivastigmine

Correct Answer
C. Memantine

Explanation
Memantine(Namenda) is an uncompetitive NMDA glutamate receptor antagonist.
Glu is the predominant excitatory neurotransmitter in the brain. Its actions a mediated by several receptors, including NMDA (N-methyl-D-Aspartate)

Glu is neurotoxic at elevated levels.

Mg is normally blocking the channel of the NMDA receptor.

Memantine replaces the physiologic role of the Mg ion to block the flow of Ca through the receptor, preventing excitotoxicity.

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12.

Which of the compounds shown would have the lowest affinity for AChE (largest Ki value)?

A.

A
B.

B
C.

C
D.

D

Correct Answer
B. B

Explanation
B. Is an alkyl carbamate. Aryl carbamates have a higher affinity for AChE than alkyl carbamates.

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13.

Which of the following is false for nicotinic receptors?

A.

The receptors in the NMJ have two binding sites of Ach
B.

Thy are voltage regulated ion channels
C.

They are contained on glycoprotiens imbedded in synaptic membranes
D.

The SAR for ligands differs for the receptors in the NMJ and the ganglia
E.

The receptors in the NMJ have a pentameric structure

Correct Answer
B. Thy are voltage regulated ion channels

Explanation
They are neurotransmitter regulated ion channels (LIGAND GATED)

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