Question 1

Thromboxane is formed in platelets, where it promotes platelet activation.The formation of thromboxane can be suppressed by inhibitors of:

Accepted Answer

A) 21-Hydroxylase. 
B) 5a-Reductase. 
C) Lipoxygenase. 
D) Desmolase. 
E) Cyclooxygenase. 
A) 21-Hydroxylase. 
B) 5a-Reductase. 
C) Lipoxygenase. 
D) Desmolase. 
E) Cyclooxygenase. E

Question 2

Increased activity of the neurotransmitter dopamine at synapses in the mesolimbic dopamine system is known to cause euphoria.Therefore, a good strategy for the development of new euphoriants is to develop drugs that:

Accepted Answer

A) Inhibit the sodium cotransporter for dopamine in the nerve terminal. 
B) Inhibit the transporter that pumps dopamine into synaptic vesicles. 
C) Inhibit tyrosine hydroxylase. 
D) Induce enhanced expression of catechol-O-methyltransferase (COMT). 
E) Block voltage-gated calcium channels in the nerve terminals. 
A) Inhibit the sodium cotransporter for dopamine in the nerve terminal. 
B) Inhibit the transporter that pumps dopamine into synaptic vesicles. 
C) Inhibit tyrosine hydroxylase. 
D) Induce enhanced expression of catechol-O-methyltransferase (COMT). 
E) Block voltage-gated calcium channels in the nerve terminals. A

Question 3

g-Aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the brain, and reduced action of GABA can lead to epileptic seizures.Therefore, a good strategy for the treatment of epilepsy would be:

Accepted Answer

A) An inhibitor of GABA decarboxylase. 
B) A drug that binds to the GABA-binding site of the GABA receptor without activating the receptor. 
C) An inhibitor of glutamate decarboxylase. 
D) An inhibitor of GABA transaminase. 
E) An inhibitor of glutamate dehydrogenase. 
A) An inhibitor of GABA decarboxylase. 
B) A drug that binds to the GABA-binding site of the GABA receptor without activating the receptor. 
C) An inhibitor of glutamate decarboxylase. 
D) An inhibitor of GABA transaminase. 
E) An inhibitor of glutamate dehydrogenase. D

Question 4

An 18-year-old girl is evaluated for primary amenorrhea.The external genitalia are unambiguously female, and secondary sexual characteristics appear normally developed.The karyotype is 46,XY.Estrogen and testosterone levels are in the normal male range.This condition is most likely caused by:

Accepted Answer

A) Deficiency of aromatase in all tissues. 
B) Deficiency of 21-hydroxylase in the adrenal cortex. 
C) Deficiency of desmolase. 
D) A defective androgen receptor. 
E) A defect of adrenocorticotropic hormone secretion from the anterior pituitary gland. 
A) Deficiency of aromatase in all tissues. 
B) Deficiency of 21-hydroxylase in the adrenal cortex. 
C) Deficiency of desmolase. 
D) A defective androgen receptor. 
E) A defect of adrenocorticotropic hormone secretion from the anterior pituitary gland.

Question 5

The release of neurotransmitters from the nerve terminal depends on an increase in the cytoplasmic level of:

Accepted Answer

A) Sodium. 
B) Calcium. 
C) Magnesium. 
D) Cyclic adenosine monophosphate. 
E) Inositol-1,4,5-trisphosphate. 
A) Sodium. 
B) Calcium. 
C) Magnesium. 
D) Cyclic adenosine monophosphate. 
E) Inositol-1,4,5-trisphosphate.

Question 6

Catecholamine biosynthesis involves dopamine (DA), epinephrine (Epi), norepinephrine (Norepi), and L-dopa (DOPA).In what sequence are these products formed?

Accepted Answer

A) Epi → Norepi → DOPA → DA. 
B) DOPA → Epi → Norepi → DA. 
C) DOPA → DA → Norepi → Epi. 
D) DA → DOPA → Epi → Norepi. 
E) Epi → Norepi → DA → DOPA. 
A) Epi → Norepi → DOPA → DA. 
B) DOPA → Epi → Norepi → DA. 
C) DOPA → DA → Norepi → Epi. 
D) DA → DOPA → Epi → Norepi. 
E) Epi → Norepi → DA → DOPA.

Question 7

Aspirin inhibits the synthesis of:

Accepted Answer

A) Prostacyclin. 
B) Leukotrienes. 
C) Platelet-activating factor. 
D) Bradykinin. 
E) Free arachidonic acid from membrane lipids. 
A) Prostacyclin. 
B) Leukotrienes. 
C) Platelet-activating factor. 
D) Bradykinin. 
E) Free arachidonic acid from membrane lipids.

Question 8

The polyunsaturated fatty acid that is most abundant in fish oils is known as eicosapentaenoic acid.It is a precursor for the synthesis of:

Accepted Answer

A) Arachidonic acid. 
B) Linoleic acid. 
C) Thromboxane A3. 
D) Platelet-activating factor. 
E) Prostaglandin E2. 
A) Arachidonic acid. 
B) Linoleic acid. 
C) Thromboxane A3. 
D) Platelet-activating factor. 
E) Prostaglandin E2.

Question 9

During the synthesis of steroid hormones, side chain cleavage reactions occur in two biotransformations.These are:

Accepted Answer

A) Glucocorticoids → mineralocorticoids and progestins →androgens. 
B) Progestins → corticosteroids and androgens → estrogens. 
C) Cholesterol → progestins and estrogens → androgens. 
D) Cholesterol → progestins and progestins → androgens. 
E) Androgens → corticosteroids and androgens → estrogens. 
A) Glucocorticoids → mineralocorticoids and progestins →androgens. 
B) Progestins → corticosteroids and androgens → estrogens. 
C) Cholesterol → progestins and estrogens → androgens. 
D) Cholesterol → progestins and progestins → androgens. 
E) Androgens → corticosteroids and androgens → estrogens.

Question 10

Renin plays a role in blood pressure regulation.What exactly does it do?

Accepted Answer

A) Contracts blood vessels and thereby raises the blood pressure. 
B) Degrades angiotensin. 
C) Makes angiotensin. 
D) Prevents the degradation of bradykinin. 
E) Stimulates the bone marrow, thereby increasing the blood volume and raising the blood pressure. 
A) Contracts blood vessels and thereby raises the blood pressure. 
B) Degrades angiotensin. 
C) Makes angiotensin. 
D) Prevents the degradation of bradykinin. 
E) Stimulates the bone marrow, thereby increasing the blood volume and raising the blood pressure.

Question 11

The polyunsaturated fatty acid eicosapentaenoic acid, which is abundant in fish oils, is a precursor for the synthesis of:

Accepted Answer

A) Arachidonic acid. 
B) Linoleic acid. 
C) Thromboxane A3. 
D) Platelet activating factor. 
E) Prostaglandin E2. 
A) Arachidonic acid. 
B) Linoleic acid. 
C) Thromboxane A3. 
D) Platelet activating factor. 
E) Prostaglandin E2.

Exam 16: Extracellular Messengers

Thromboxane is formed in platelets, where it promotes platelet activation.The formation of thromboxane can be suppressed by inhibitors of:

Increased activity of the neurotransmitter dopamine at synapses in the mesolimbic dopamine system is known to cause euphoria.Therefore, a good strategy for the development of new euphoriants is to develop drugs that:

g-Aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the brain, and reduced action of GABA can lead to epileptic seizures.Therefore, a good strategy for the treatment of epilepsy would be:

An 18-year-old girl is evaluated for primary amenorrhea.The external genitalia are unambiguously female, and secondary sexual characteristics appear normally developed.The karyotype is 46,XY.Estrogen and testosterone levels are in the normal male range.This condition is most likely caused by:

The release of neurotransmitters from the nerve terminal depends on an increase in the cytoplasmic level of:

Catecholamine biosynthesis involves dopamine (DA), epinephrine (Epi), norepinephrine (Norepi), and L-dopa (DOPA).In what sequence are these products formed?

Aspirin inhibits the synthesis of:

The polyunsaturated fatty acid that is most abundant in fish oils is known as eicosapentaenoic acid.It is a precursor for the synthesis of:

During the synthesis of steroid hormones, side chain cleavage reactions occur in two biotransformations.These are:

Renin plays a role in blood pressure regulation.What exactly does it do?

The polyunsaturated fatty acid eicosapentaenoic acid, which is abundant in fish oils, is a precursor for the synthesis of:

Introduction to Biomolecules

Introduction to Protein Structure

Oxygen Transporters: Hemoglobin and Myoglobin

Enzymatic Reactions

Coenzymes

DNA, RNA, and Protein Synthesis

The Human Genome

Protein Targeting

Introduction to Genetic Diseases

Viruses

DNA Technology

Biological Membranes

The Cytoskeleton

The Extracellular Matrix

Plasma Proteins

Intracellular Messengers

Cellular Growth Control and Cancer

Digestive Enzymes

Introduction to Metabolic Pathways

Glycolysis, Tricarboxylic Acid Cycle, and Oxidative Phosphorylation

Carbohydrate Metabolism

The Metabolism of Fatty Acids and Triglycerides

The Metabolism of Membrane Lipids

Lipid Transport

Amino Acid Metabolism

Heme Metabolism

The Metabolism of Purines and Pyrimidines

Vitamins and Minerals

Integration of Metabolism

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