Biochemistry: Lect 4. Flashcards by Ashley Moss

Catecholamines are structurally derived from which amino acid according to the source?
a) Tryptophan
b) Histidine
c) Tyrosine
d) Phenylalanine

c) Tyrosine

How well did you know this?

Not at all

Perfectly

Catecholamines are classified as which type of hormone based on their solubility?
(a) Lipophilic hormones requiring carrier proteins
(b) Hydrophilic hormones that do not typically need carrier proteins
(c) Gaseous hormones that diffuse freely across membranes
(d) Steroid hormones that bind to intracellular receptors
(e) Thyroid hormones bound to transport proteins

(b) Hydrophilic hormones that do not typically need carrier proteins

How well did you know this?

Not at all

Perfectly

Hydrophilic hormones like catecholamines typically bind to which type of receptors?
a) Intracellular receptors
b) Nuclear receptors
c) Cell surface receptors
d) Cytosolic receptors

c) Cell surface receptors - plasma membrane

How well did you know this?

Not at all

Perfectly

The cell surface receptors for catecholamines are usually coupled with:
a) Ion channels
b) Enzyme-linked receptors
c) G protein-coupled receptors
d) Steroid hormone receptors

c) G protein-coupled receptors

Note: Also, use cAMP, Ca2+ or phosphatidyl-inositols in signal transduction cascades

How well did you know this?

Not at all

Perfectly

According to the source, norepinephrine and epinephrine are released in response to:
a) Rest and digestion
b) Increased parasympathetic activity
c) Cold, fright, exercise
d) Decreased heart rate

c) Cold, fright, exercise

How well did you know this?

Not at all

Perfectly

Epinephrine works synergistically with which other hormone to combat low blood glucose levels?
a) Insulin
b) Glucagon
c) Cortisol
d) Growth hormone

b) Glucagon

How well did you know this?

Not at all

Perfectly

What is the primary role of dopamine as described in the source?
a) Regulation of metabolism
b) “Emergency hormone”
c) Neurotransmitter
d) Vasoconstriction

c) Neurotransmitter

How well did you know this?

Not at all

Perfectly

In which location are all catecholamines mentioned in the source synthesized?
a) Adrenal cortex
b) Pancreatic islets
c) Thyroid gland
d) Chromaffin cells of the adrenal medulla

d) Chromaffin cells of the adrenal medulla

How well did you know this?

Not at all

Perfectly

A deficiency of dopamine in the brain is associated with which condition?
a) Alzheimer’s disease
b) Huntington’s disease
c) Parkinson’s disease
d) Multiple sclerosis

c) Parkinson’s disease

Note: Dopa decarboxylase inhibitions treats Parkinson’s

How well did you know this?

Not at all

Perfectly

What percentage of total catecholamine released by the adrenal medulla does norepinephrine account for, according to the source?
a) 10%
b) 20%
c) 50%
d) 80%

b) 20%

How well did you know this?

Not at all

Perfectly

Epinephrine is described in the source as the:
a) “Rest and digest” hormone
b) “Fight or flight” neurotransmitter
c) “Emergency hormone”
d) “Growth” hormone

c) Adrenaline — “Emergency hormone”

How well did you know this?

Not at all

Perfectly

According to the source, epinephrine has its main actions on:
a) Kidneys and liver
b) Brain and muscles
c) Blood vessels, heart, and metabolism
d) Lungs and digestive system

c) Blood vessels, heart, and metabolism

Effects:
Increases blood pressure
Increase cardiac activity
Promotes bronchia
Helps converts glycogen into glucose in liver and muscles

How well did you know this?

Not at all

Perfectly

What percentage of the catecholamines in the adrenal medulla does epinephrine represent according to the source?
a) 20%
b) 30%
c) 50%
d) 80%

d) 80%

How well did you know this?

Not at all

Perfectly

Compared to norepinephrine, epinephrine has a greater effect on:
a) Neurotransmission
b) Vasoconstriction
c) Metabolism
d) Bronchodilation

c) Metabolism

How well did you know this?

Not at all

Perfectly

Signal transduction cascades initiated by catecholamine binding to their receptors commonly involve which of the following second messengers?
(a) Cyclic GMP
(b) Insulin
(c) Glucagon
(d) cAMP, Ca2+, or phosphatidyl-inositols
(e) Thyroid hormone

(d) cAMP, Ca2+, or phosphatidyl-inositols

How well did you know this?

Not at all

Perfectly

The role of norepinephrine in metabolism, compared to other hormones, is considered: (a) Major regulator of glucose uptake
(b) Primary driver of lipolysis
(c) Dominant in protein synthesis
(d) Minimal in carbohydrate and lipid metabolism
(e) Essential for mineralocorticoid production

(d) Minimal in carbohydrate and lipid metabolism

How well did you know this?

Not at all

Perfectly

Stimulation of the adrenal medulla by which type of nerves leads to the release of epinephrine?
(a) Preganglionic parasympathetic nerves
(b) Postganglionic sympathetic nerves
(c) Preganglionic sympathetic nerves
(d) Sensory afferent neurons
(e) Motor efferent neurons

How well did you know this?

Not at all

Perfectly

In which tissues is epinephrine synthesized?
(a) Brain and spinal cord
(b) Adrenal cortex and kidney
(c) Adrenal medulla only
(d) Liver and skeletal muscle
(e) Pancreas and thyroid gland

How well did you know this?

Not at all

Perfectly

What is the initial precursor molecule in the biosynthesis of all catecholamines?
(a) Tryptophan
(b) Phenylalanine
(c) Serotonin
(d) Tyrosine
(e) Histidine

Study These Flashcards

(d) Tyrosine

The first enzymatic step in catecholamine synthesis involves:
(a) Decarboxylation of DOPA
(b) Hydroxylation of dopamine
(c) Ring hydroxylation of tyrosine to DOPA
(d) N-methylation of norepinephrine
(e) Oxidation of homovanillic acid

Study These Flashcards

What enzymatic reaction is catalyzed by DOPA decarboxylase?
(a) Conversion of tyrosine to DOPA
(b) Conversion of DOPA to dopamine
(c) Conversion of dopamine to norepinephrine
(d) Conversion of norepinephrine to epinephrine
(e) Methylation of catechol

Study These Flashcards

(b) Conversion of DOPA to dopamine

The conversion of dopamine to norepinephrine is catalyzed by which enzyme?
(a) Tyrosine hydroxylase
(b) DOPA decarboxylase
(c) Dopamine β-hydroxylase
(d) Phenylethanolamine-N-methyltransferase
(e) Monoamine oxidase

Study These Flashcards

Add -OH to the B carbon chain

The final step in the synthesis of epinephrine involves the N-methylation of norepinephrine by which enzyme?
(a) Tyrosine hydroxylase
(b) DOPA decarboxylase
(c) Dopamine β-hydroxylase
(d) Phenylethanolamine-N-methyltransferase
(e) Catechol-O-methyltransferase

Study These Flashcards

(d) Phenylethanolamine-N-methyltransferase

Which of the following is true regarding tyrosine hydroxylase?
(a) It is primarily found in erythrocytes.
(b) Its activity is independent of catecholamine levels.
(c) The reaction it catalyzes is the rate-limiting step in catecholamine synthesis.
(d) It catalyzes the decarboxylation of DOPA.
(e) It is competitively inhibited by vitamin C.

Study These Flashcards

Tyrosine hydroxylase requires which cofactor for its enzymatic activity? (a) Pyridoxal phosphate (vitamin B6) (b) Ascorbate (vitamin C) (c) S-adenosylmethionine (SAM) (d) Tetrahydropterine (e) Flavin adenine dinucleotide (FAD)

(d) Tetrahydropterine Other characteristics: Inhibited by tyrosine derivatives and catecholamines

Dopa decarboxylase requires which vitamin derivative as a cofactor? (a) Tetrahydropterine (b) Ascorbate (vitamin C) (c) Pyridoxal phosphate (vitamin B6) (d) S-adenosylmethionine (SAM) (e) Thiamine pyrophosphate (vitamin B1)

Inhibition of DOPA decarboxylase is used in the treatment of Parkinson's disease to: (a) Increase dopamine synthesis in the periphery (b) Prevent the peripheral metabolism of L-DOPA (c) Enhance norepinephrine production in the brain (d) Reduce the side effects of epinephrine (e) Inhibit the reuptake of dopamine in the synaptic cleft

(b) Prevent the peripheral metabolism of L-DOPA

Phenylethanolamine-N-methyltransferase (PNMT) requires which cofactor for the N-methylation reaction? (a) Tetrahydrofolate (b) Nicotinamide adenine dinucleotide (NAD+) (c) Flavin mononucleotide (FMN) (d) S-adenosylmethionine (SAM) (e) Coenzyme A

(d) S-adenosylmethionine (SAM)

Dopamine β-hydroxylase utilizes which vitamin as an electron donor? (a) Vitamin B12 (b) Vitamin D (c) Vitamin K (d) Vitamin C (ascorbate) (e) Vitamin E

(d) Vitamin C (ascorbate) Also used fumerate and copper.

The synthesis of PNMT in the adrenal medulla is induced by: (a) Insulin (b) Glucagon (c) Glucocorticoid hormones (d) Thyroid hormones (e) Estrogen

What is the primary function of chromaffin cells? (a) Synthesis and secretion of steroid hormones (b) Production of thyroid hormones (c) Synthesis, storage, and secretion of catecholamines into the bloodstream (d) Regulation of blood glucose through insulin and glucagon release (e) Filtration of waste products from the blood

Catecholamines are stored within chromaffin cells in which subcellular structures? (a) Lysosomes (b) Mitochondria (c) Endoplasmic reticulum (d) Granules (storage vesicles) (e) Golgi apparatus

(d) Granules (storage vesicles)

A key difference between sympathetic neurons and adrenal chromaffin cells is that sympathetic neurons primarily discharge: (a) Epinephrine systemically (b) Dopamine locally (c) Norepinephrine locally (d) Acetylcholine into the bloodstream (e) Serotonin into the cerebrospinal fluid

Pheochromocytoma is a disorder characterized by: (a) Hyposecretion of adrenal androgens (b) Hypersecretion of cortisol (c) Very high circulating levels of catecholamines due to a chromaffin cell tumor (d) Autoimmune destruction of adrenal cortical cells (e) Impaired synthesis of thyroid hormones

Common symptoms associated with pheochromocytoma include: (a) Weight gain, moon face, and buffalo hump (b) Fatigue, muscle weakness, and low blood pressure (c) High blood pressure, pounding headaches, and heart palpitations (d) Cold intolerance, dry skin, and weight loss (e) Excessive thirst, frequent urination, and elevated blood glucose

Re-uptake of catecholamines from the synaptic cleft is primarily performed by: (a) Postsynaptic receptors (b) Enzymes in the extracellular space (c) Sympathetic nerve terminals (d) Bloodstream transport proteins (e) Glial cells

The re-uptake mechanism of catecholamines is important for: (a) Stimulating further hormone synthesis (b) Prolonging the duration of hormonal action (c) Conserving hormones, which are made using essential amino acids (d) Facilitating the transport of catecholamines to distant tissues (e) Enhancing the degradation of catecholamines

The uptake of norepinephrine and dopamine by nerve terminals is facilitated by: (a) Passive diffusion across the cell membrane (b) Voltage-gated ion channels (c) An amine pump driven indirectly by a Na+ gradient (d) Receptor-mediated endocytosis (e) Facilitated transport via glucose transporters

The amine uptake pump responsible for catecholamine re-uptake is inhibited by substances such as: (a) Acetylcholine and GABA (b) Insulin and glucagon (c) Cocaine, amphetamine, and methamphetamine (d) Cortisol and aldosterone (e) Thyroid hormones

What is the primary fate of catecholamines synthesized by the adrenal medulla, given that the adrenal medulla lacks an uptake mechanism? (a) They are primarily stored indefinitely within chromaffin cells. (b) They are rapidly transported to the brain for neurotransmission. (c) They are primarily degraded by enzymes in the liver and muscle. (d) They are efficiently reabsorbed by the kidneys and recycled. (e) They bind to circulating carrier proteins for long-term transport.

The degradation of catecholamines involves the action of which two main enzymes? (a) Peptidases and lipases (b) Kinases and phosphatases (c) Monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) (d) Polymerases and ligases (e) Amylase and protease

Discuss the end products of E and NE degradation

Discuss the end products of DA degradation.

Inhibition of MAO and COMT can have a therapeutic effect in Parkinson's disease by: (a) Increasing the synthesis of dopamine (b) Slowing down the degradation of dopamine (c) Enhancing the reuptake of dopamine (d) Stimulating dopamine receptors (e) Promoting the release of dopamine from storage vesicles

(b) Slowing down the degradation of dopamine

MAO inhibitors are used for?

Antidepressants. They prevent the degradation of epinephrine

Biochemistry: Lect 4. Flashcards

(45 cards)