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BIOCHEMISTRY MED1 > Hormones I > Flashcards

Hormones I Flashcards

1
Q 
Which hormones require neural stimulation for them to be released?
A. Epinephrine
B. Norepinephrine
C. Renin
D. A and B
E. AOTA
A

D. AOTA

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2
Q 
Which of the following characterizes Neural Communication and NOT hormonal?
A. Short term effects
B. No voluntary control
C. Mobile messages
D. Slow onset of action
A

A. Short term effects

Neural communications are:

  • fixed communication system
  • have fast onset of action
  • have short term effects
  • partially voluntary (e.g. muscle cotnraction)
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3
Q

A cell with the ability to bind selectively a given hormone via a cognate receptor

A

Target cell

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4
Q

A factor determining concentration of hormone at target cell in relation to its dissociation constant:

A

Affinity with specific plasma proteins

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5
Q

Factors affecting hormone concentration at target cell in relation to dilution effect:

A

Proximity of the target cell to hormone source

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6
Q

Which of the following affects the actual response of the target cell to the hormone?
A. Affinity of the hormone to plasma protein
B. Proximity of the target cell to the hormone source
C. Metabolism of the hormone in the target cell
D. Rate of clearance of hormone from the plasma
E. Conversion of inactive or sub-optimally active forms of the hormone into the fully active form

A

C. Metabolism of the hormone in the target cell

The rest of the choices are factors affecting the hormone CONCENTRATION

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7
Q

Which of the following is not a factor affecting the actual response of the target cell to the hormone?
A. Number, relative activity and state of occupancy of the specific receptors
B. Rate of synthesis and secretion of hormone
C. Presence of factors within the cell that are necessary for hormone response
D. Up or down regulation of the receptor upon ligand interaction
E. Post-receptor desensitization

A

B. Rate of synthesis and secretion of hormone

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8
Q

Cell-associated recognition molecules that are proteins in nature exhibiting a high degree of specificity and discrimination of a hormone

A

Receptors

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9
Q

Which of the following is an important biochemical feature for hormone-receptor interaction?
A. Binding should be specific
B. Binding should be saturable
C. Binding should occur within the concentration range of the expected biological response
D. Binding is displaceable by agonist or antagonist
E. AOTA

A

E. AOTA (Harper 499)

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10
Q

Which of the following is true?
A, Glucocorticoid hormones directly enter the nucleus
B. Thyroid hormones and retinoic acid encounter their cognate receptor in the cytoplasm
C. With thyroid receptors, ligand binding results in dissociation of coactivator complex from the receptor
D. Cognate heterodimeric receptors of thyroid hormones are already bound to the appropriate response elements
E. Glucocorticoid receptor exists in a complex with hsp60

A

D. Cognate heterodimeric receptors of thyroid hormones are already bound to the appropriate response elements

Glucocorticoid hormones (solid triangles) encounter their cognate receptor (GR) in the cytoplasm, where GR exists in a complex with a chaperone protein, heat shock protein 90 (hsp).
By contrast, thyroid hormones
and retinoic acid directly enter the nucleus, where their cognate heterodimeric receptors are already bound to the appropriate response elements with an associated transcription corepressor complex. Ligand binding results in dissociation of the corepressor complex from the receptor, allowing an activator complex, consisting of the TR-TRE and coactivator, to assemble.

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11
Q

Receptors of no known ligands are called:

A

Orphan receptors

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12
Q

Which hormone receptor types are members of a large super family of nuclear receptors?

A

Steroid and Thyroid type

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13
Q 
Liver cells have more than one receptor. Which of the following is NOT a hormone that target the liver cells?
A. Glucagon
B. Insulin
C. Thyroxine
D. Epinephrine
E. Cortisol
A

C. Thyroxine

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14
Q

This accurately describes the relation of ligand to target cell:
A. One ligand can affect different cell types.
B. More than one ligand can affect a single cell type.
C. One ligand can exert many different effects in one or more target cells.
D. Many different molecules circulate in the extracellular fluid, but only a few are recognized by hormone receptors
E. AOTA

A

E. AOTA

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15
Q

Which of the following does not characterize a hormone?
A. High affinity for a receptor
B. Irreversible binding
C. No additive effect once all receptors are occupied
D. Occur within a concentration of the expected biological response
E. Specific and Saturable

A

B. (should be reversible)

C. is the definition of saturable
D. is the definition of specific

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16
Q

What are the functional domains of receptors?

A

Recognition and Coupling domain

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17
Q 
Which functional domain of a receptor is responsible for signal transduction?
A. Extracellular domain
B. Recognition Domain
C. Coupling Domain
D. Ligand domain
E. NOTA
A

C. Coupling domain

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18
Q

Which of the following is NOT true of the coupling domain?
A. the transmembrane portion
B. faces the cytoplasm
C. couples hormone recognition with some intracellular function
D. binds the hormone
E. for receptor-effector coupling

A

D. (function of recognition domain)

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19
Q

Which of the following is NOT true of the coupling domain?
A. the transmembrane portion
B. faces the cytoplasm
C. couples hormone recognition with some intracellular function
D. binds the hormone

A

D. is for recognition domain

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20
Q

Which of the two classes of receptors generates signals that regulate various intracellular functions?

A

Membrane or Cell surface receptors

(Intracellular receptors provide signals to specific genes to affect rate of transcription via genomic activation or silencing)

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21
Q 
Which of the following DOES NOT characterize cell surface receptors?
A. can close or open channels
B. can regulate protein synthesis
C. can inactivate enzymes
D. can affect cytoskeletal proteins
E. NOTA
A

B. is a function of intracellular receptors via regulation of gene transcription

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22
Q 
Which of the following DOES NOT utilize intracellular receptors?
A. IGF-1
B. cortisol
C. vitamin A
D. thyroxine
E. vitamin D
A

A. IGF-1 (a hydrophilic hormone; note that although it’s Group II, it requires transport protein)

IGF-1 (Jak-Stat pathway), insulin (tyrosine kinase), Protein, polypeptide and catecholamines (GPCR) utilize membrane/ cell surface receptors

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23
Q

This dual function mechanism provides the first step in amplification of the hormonal response

A

Receptor-effector coupling

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24
Q 
The α subunit of the G protein includes which characteristic?
A. ATPase activity
B. Hydrolytic activity
C. GTPase activity
D. K+ channel stimulation
E. PLC activation
A

C. GTPase activity

D and E:
The βγ complexes have been associated with K+ channel stimulation and phospholipase C activation. (Harper 522)

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25
Q 
A phosphodiesterase can terminate response by converting cAMP to:
A. ADP
B. 3'-ADP
C. 5'-AMP
D. ATP
E. 3'-AMP
A

C. 5’-AMP

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26
Q 
PKA exists in an inactive form as:
A. R2C2 heterotetramer
B. R1C1 heterodimer
C. RaRb homodimer
D. RaCa homodimer
E. NOTA
A

A. R2C2 heterotetramer

PKA exists in an inactive form as an R2C2 heterotetramer consisting of two regulatory (R) and two catalytic (C) subunits.

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27
Q

Which subunit of PKA, with the presence of cAMP, is activated after dissociation?

A

Catalytic subunits

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28
Q

Which of the following is a function of activated PKA?
A. converts proteins to phosphoprotein
B. phosphorylates proteins at Ser and Thr residues
C. removes phosphates from Ser and Thr residues
D. Both A and B
E. AOTA

A

D.
The active catalytic subunits [of PKA] phosphorylate a number of target proteins on serine and threonine residues [with Mg++ and ATP]. Phosphatases remove phosphate from these residues and thus terminate the physiologic response.

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29
Q

IGF-1 activates which signaling pathway?

A

Jak-Stat pathway

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30
Q

Polypeptides and Catecholamines utilizes which specific type of receptor?

A

GPCR

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31
Q

Insulin utilizes which specific type of receptor?

A

Tyrosine kinase (Class II: Cysteine family)

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32
Q 
Which receptor subunit serves as hormone-binding domain for insulin?
A. Alpha subunits
B. Beta subunits
C. Gamma subunits
D. Delta subunits
E. Epsilon subunits
A

A. Alpha subunits

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33
Q 
Which receptor subunit serves as ATP-binding domains for insulin?
A. Alpha subunits
B. Beta subunits
C. Gamma subunits
D. Delta subunits
E. Epsilon subunits
A

B. Beta subunits

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34
Q

Autophosphorylation of intracellular enzymes as instigated by insulin binding will activate which signaling pathway?
A. Phosphoinositide 3-kinase pathway
B. Mitogen-activated protein kinase pathway
C. Janus kinase pathway
D. Both A and B
E. AOTA

A

D.
→ Activates PI-3K signaling pathway that will cause the exteriorization of GLUT4
→ Activates MAP Kinase signaling pathway (mitogenic effects) which will phosphorylate certain proteins, or activate certain translation factors which will cause cell growth and gene expression via protein synthesis

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35
Q

Which of the following is included in the domains of Group I hormone receptors?
A. Domain responsible for hormone binding
B. Domain that binds to specific DNA sequences
C. Site that interacts with coregulator proteins
D. Domain that specifies binding to proteins that influence intracellular trafficking of receptor
E. AOTA

A

E. AOTA

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36
Q

What class of hormone (based on chemical composition) is calcitriol?

A

Steroid hormone

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37
Q

Amino acid derivative hormones are synthesized from the amino acid:

A

Tyrosine

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38
Q

2 Hormones derived from Tyr:

A

Catecholamines

Thyroid hormones

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39
Q

Glycoprotein hormones are:
A. Homodimer
B. Heterodimer

A

B. Heterodimer
Same α subunit but different β subunit
- FSH, LH, CG and TSH
The α-GSU is common to TSH, FSH, and LH, whereas the β subunit is specific to the hormone (i.e., β-TSH, β-FSH, and β-LH are all unique).

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40
Q

Class (by chemical composition) of Anterior pituitary hormones

A

Peptide/Protein hormones

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41
Q

Histamine is derived from which amino acid?
A. His
B. Trp
C. Tyr

A

A. Histidine

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42
Q

Serotonin is derived from which amino acid?
A. His
B. Trp
C. Tyr

A

B. tryptophan

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43
Q

Melatonin is derived from which amino acid?
A. His
B. Trp
C. Tyr

A

B. tryptophan

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44
Q 
Which of the following hormones are derived from fatty acids?
A. Prostaglandins
B. Prostacyclins
C. Thromboxanes
D. Leukotrienes
E. AOTA
A

E. AOTA

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45
Q

What is the intracellular messenger of Group I hormones?

A

Hormone-receptor complex itself

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46
Q

Group (by solubility property) of Eicosanoids

A

Group II

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47
Q

Location of receptors for lipid soluble ligands
A. On the outer surface of the plasma membrane
B. On the inner surface of the plasma membrane
C. On Organelles

A

C. On Organelles

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48
Q

Location of Receptors for intracellular signaling
A. On the outer surface of the plasma membrane
B. On the inner surface of the plasma membrane
C. On Organelles

A

B. On the inner surface of the plasma membrane

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49
Q

Receptors for water soluble ligands
A. On the outer surface of the plasma membrane
B. On the inner surface of the plasma membrane
C. On Organelles

A

A. On the outer surface of the plasma membrane

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50
Q

For group II hormones can be further subdivided into four groups. What is the group for those with kinases of phosphate cascade as their 2nd messengers?

A

Group IID

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51
Q

For group II hormones can be further subdivided into four groups. What is the group for those with cGMP as their 2nd messengers through guanylyl cyclase?

A

Group IIB

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52
Q

For group II hormones can be further subdivided into four groups. What is the group for those with calcium ion and phosphatidylinositol as their 2nd messengers through Phospholipase C?

A

Group IIC

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53
Q 
Which of the following does not utilize cAMP as second messenger?
A. α1-adrenergic catecholamines
B. a2-adrenergic catecholamines
C. B-adrenergic catecholamines 
D. calcitonin
E. Chorionic gonadotropin, human (CG)
A

A. α1-adrenergic catecholamines (calcium or phosphatidylinositols (or both))

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54
Q 
Which of the following does not utilize calcium or phosphatidylinositols (or both) as second messenger?
A. Oxytocin
B. Platelet-derived growth factor (PDGF)
C. Substance P
D. Thyrotropin-releasing hormone (TRH)
E. Prolactin
A

E. Prolactin (kinase or phosphatase cascade)

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55
Q 
Which of the following does not utilize kinase or phosphatase cascade as second messenger?
A. Adiponectin
B. Leptin
C. CCK
D. Erythropoietin
E. Chorionic somatomammotropin
A

C. CCK (Ca++ or PI3)

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56
Q

Anterior pituitary hormones that do not belong to Group IIA:

A

GH and Prolactin (Group IID)

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57
Q

ADH belongs to which groups of hormone according to receptor location?

A

Groups IIA and IIC

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58
Q

Which growth factor belongs to Groups IIC and IID

A

Platelet-derived Growth Factor

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59
Q

Final organ to produce active form of Vitamin D

A

Kidneys

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60
Q

storage location of catecholamines

A

chromaffin granules

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61
Q

Conversion of testosterone to its active form (DHT) happens in which organs?

A

skin and prostate

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62
Q 
Which of the following do not have intracellular reservoir?
A. Steroid hormones
B. Thyroid hormones
C. Catecholamines
D. Insulin
A

A. Steroid hormones
Thyroid hormones – stored for weeks
Catecholamines and PTH – hours
Insulin – several days

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63
Q

Hormones bound to transport proteins are not recognized by which enzymes in the liver?

A

Cytochrome enzymes for degradation

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64
Q

This represents the

circulating reservoir for hormones

A

Transport proteins

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65
Q

True or False:

When hormones are bound to transport proteins – they are inactive

A

True

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66
Q

Which thyroid hormone has a higher affinity to transport

proteins?

A

T4

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67
Q

Which thyroid hormone is more potent?

A

T3

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68
Q

Main androgen in the zona reticularis

A

DHEA

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69
Q

A small percentage of steroid hormone is produced in situ from:

A

Acetyl-CoA via mevalonate and squalene

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70
Q

During storage, free cholesterol is esterified to cholesterol ester once inside cytoplasm by which enzyme?

A

Acetyl-CoA acyltransferase

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71
Q

Enzyme that converts cholesterol ester to free cholesterol

A

Cholesterol ester hydrolase (esterase)

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72
Q

The rate-limiting step for steroidogenesis

A

ACTH-dependent diffusion of free cholesterol into the mitochondria by uptake of StAR (steroidogenic acute
regulatory) protein

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73
Q 
Pregnenolone production is catalyzed by: 
A. CYP11A1 
B. P450scc
C. CYP17
D. Either A or B
E. NOTA
A

D.

74
Q

The action of P450scc on cholesterol is
A. sequential hydroxylation at C21 and C20
B. sequential hydroxylation at C22 and C20
C. sequential hydroxylation at C22 and C21
D. sequential hydroxylation at C21 and C23

A

B. sequential hydroxylation at C22 and C20

75
Q 
Which of the following is not an effect of estrogen?
A. Increases vasodilation
B. Increases HDL synthesis
C. Activates Lipoprotein lipase
D. Cell proliferation
A

C. should be Hormone-sensitive lipase

76
Q

2 hormones that increase the receptors for LH

A

FSH and estrogen

77
Q

These enzymes for mineralocorticoid synthesis are only found in the zona glomerulosa

A

18-hydroxylase

18-hydroxysteroid dehydrogenase

78
Q

These are the most potent regulators of aldosterone

A

K+ levels and Angiotensin II

79
Q

These are mitochondrial enzymes encountered by pregnenolone to convert it to progesterone

A

3β-hydroxysteroid dehydrogenase (converts to ketone)
and
Δ5,4-isomerase (transfers double bond from C5 to C4)

80
Q

This adrenal cortical enzyme has both glucocorticoid and mineralocorticoid activity

A

21-hydroxylase (converts progesterone/17-hydroxyprogesterone to 11-DOC

81
Q

A mitochondrial enzyme that converts 11-DOC to corticosterone

A

11β-hydroxylase

82
Q

What are the enzymes required for glucocorticoid synthesis?

A

17-, 21-, 11β-hydroxylases

83
Q

The action of this enzyme on pregnenolone will set the path of steroidogenesis to glucocorticoid synthesis

A

17α-hydroxylase (attaches a hydroxyl group at C17 to yield 17-hydroxypregnenolone)

84
Q

The main transport protein for glucocorticoids

A

Cortisol-binding globulin (Transcortin)

the other is albumin

85
Q

Hormone that increases the synthesis of CBG in the liver

A

Estrogen

86
Q

Steroid hormones that will bind with high affinity on CBG

A

DOC (deoxycorticosterone) and Progesterone

87
Q

Steroid that weakly binds with CBG

A

Gonadal steroids:

Estradiol, estrone, testosterone, DHT

88
Q

DHEA being acted on by 3β-HD and Δ5,4-Isomerase will yield the more potent:

A

Androstenedione

89
Q

This double-function enzyme converts the pregnenolone to the major androgen, DHEA

A

17-hydroxylase (with 17, 20-lyase function)

90
Q

Enzyme that converts Androstenedione into Testosterone in the testis

A

17β-hydroxysteroid dehydrogenase

91
Q

2 pathways for testicular steroidogenesis:

A

Progesterone (Delta-4 pathway) and

DHEA (Delta-5 pathway)

92
Q

Which enzyme will set the path of testicular steroidogenesis to delta-4 pathway?

A

3β-HD and Δ5,4-isomerase

93
Q

The predominant pathway of testicular steroidogenesis

A

Delta-5 or DHEA pathway

94
Q 
What reaction inactivates Testosterone?
A. Oxidation of C17
B. Reduction of C17
C. Oxidation of the A-ring double bond
D. Reduction of the A-ring double bone
A

A. Oxidation of C17

95
Q

Conversion of Testosterone to the more potent Dihydrotestosterone (DHT) is by the action of the enzyme:

A

5α-reductase (NADPH-dependent)

96
Q

Precursor for the most potent type of estrogen

A

Testosterone

precursor to 17β-estradiol

97
Q

Precursor to the post-menopausal type of estrogen

A

Androstenedione (precursor to estrone)

98
Q

This is the estrogen of adrenal origin

A

Estrone

99
Q

The estrogen of pregnancy is produced by the:

A

placenta

100
Q

What catalyzes the formation of estrogens via peripheral aromatization of androgens

A

Aromatase Enzyme Complex

101
Q 
The synthesis of estrogen from androgens requires the following, except:
A. 3 hydroxylation steps
B. Oxygen
C. NADPH
D.NADH
E. Aromatase Enzyme Complex
A

D. NADH

102
Q

Which cells of the ovary is the Aromatase Enzyme Complex found?

A

Granulosa cells

103
Q

What enzyme is produced by the placenta to convert estrone to estriol?

A

16α-hydroxylase

104
Q

Cell source of testosterone and androstenedione in Female

A

Theca cells

105
Q 
Which of the following organs is not a source of aromatase?
A. Liver
B. Skin
C. Adipose tissue
D. Uterus
E. Breast
A

D. Uterus

106
Q

In which structure is the progesterone the end product due to its lack of enzymes for the progression of steroidogenesis?

A

Corpus luteum

107
Q

Hormone that increases the production of Sex Hormone Binding Globulin

A

Estrogen

108
Q

True or False:

TEBG has higher affinity to estrogen than testosterone

A

False:

Testosterone-Estrogen Binding globulin has higher affinity with testosterone

109
Q

Which hormone helps the body absorb calcium from the GIT?

A

Calcitriol

110
Q

Between a light and dark-skinned individual, who has more Vitamin D?

A

Lighter skinned because melanin shields the skin from UV rays

111
Q

Precursor of Vitamin D3 produced with exposure to UV light

A

7-dehydrocholesterol

112
Q

Which liver enzyme converts cholecalciferol to 25-hydroxycholecalciferol?

A

NADPH-dependent cytochrome P450 reductase and CytP450

Vitamin D3-25-hydroxylase

113
Q

Which renal enzyme converts 25-hydroxycholcalciferol to the active form of Vitamin D?

A

1α-hydroxylase

114
Q

The predominant form of Vitamin D in the plasma

A

25-hydroxycholecalciferol or Vitamin D3

115
Q

The active form of vitamin D

A

1,25-dihydroxycholecalciferol or Calcitriol

116
Q

Calcitriol will increase absorption of which substances in the intestine? (2) answers

A

Calcium and Phosphate

117
Q

In which layer/s of the epidermis is the 7-dehydrocholesterol found?

A

Malpighian layer of the epidermis

118
Q

In which organelle does the conversion of Vit D3 to 25(OH)-D3 occur?

A

ER

119
Q 
The following is required in the conversion of D3 to 25(OH)-D3, except:
A. Fe++
B. Mg++
C. NADPH
D. O2
E. uncharacterized cytoplasmic factor
A

A. Fe++

120
Q

In which organelle does the conversion of 25(OH)-D3 to calcitriol occur?

A

mitochondria

hydroxylation of C1

121
Q

What are the enzymes involved in the final step of calcitriol synthesis?

A 
Renal Ferredoxin reductase (flavoprotein)
Renal Ferredoxin (Iron-sulfur protein)
Cytochrome P450
122
Q

The major adrenal medulla product

A

Epinephrine

123
Q

Catecholamines are derived from which amino acid?

A

Tyrosine

124
Q

Which of the following is the correct sequence of catecholamine synthesis?
A. Side chain hydroxylation > Ring hydroxylation > Side chain decarboxylation > Side chain N-methylation
B. Ring hydroxylation > Side chain decarboxylation > Side chain hydroxylation > Side chain N-methylation
C. Side chain N-methylation > Side chain hydroxylation > Ring hydroxylation > Side chain decarboxylation

A

B. Ring hydroxylation > Side chain decarboxylation > Side chain hydroxylation > Side chain N-methylation

125
Q

The rate-limiting enzyme of catecholamine synthesis

A

Tyrosine hydroxylase

126
Q

Cofactor needed in the first step of catecholamine synthesis

A

Tetrahydrobiopterin

127
Q

The first 2 steps of catecholamine synthesis occur in which part of the chromaffin cell?

A

cytoplasm

128
Q

The decarboxylation of side chain in catecholamine biosynthesis requires which coenzyme?

A

Pyridoxal phosphat

129
Q

The decarboxylation of side chain in catecholamine biosynthesis requires which coenzyme?

A

Pyridoxal phosphate

130
Q

The last 2 steps of catecholamine synthesis occur in which compartment of the chromaffin cells?

A

chromaffin granules

131
Q

the action of dopamine-β-hydroxylase requires which compounds?

A

Ascorbate
Copper
Fumarate

132
Q

Modulator compound in the synthesis of NE

A

Fumarate

133
Q

Compound found in the active site of the enzyme responsible for the formation of NE

A

Copper

134
Q

Electron donor in the production of NE

A

Ascorbate

135
Q

Which hormone promotes the conversion of NE to Epinephrine?

A

Cortisol

136
Q

Enzyme activated by the stimulation of cortisol to produce EPI

A

Phenylethanolamine-N-methyltransferase (PNMT)

137
Q

Which enzyme is inhibited by the presence of epinephrine?

A

tyrosine hydroxylase

138
Q

The degradation of catecholamines is catalyzed by which enzymes?

A

Monoamine oxidase and

Catechol-O-methyltransferase (COMT)

139
Q

The end product of catecholamine degradation

A

vanillylmandelic acid (VMA)

140
Q

Which product is expected to increase in the urine with pheochromocytoma?

A

VMA

141
Q

The glycosylated protein precursor of thyroid hormones

A

thyroglobulin

142
Q

The majority of iodine in thyroglobulin are found in its inactive precursors:

A

Monoiodotyrosine and Diiodotyrosine

143
Q

Stimulation by ___ increases all aspects of thyroid hormone biosynthesis

A

Thyroid Stimulating Hormone

144
Q

The prohormone released by the thyroid gland

A

Thyroxine

145
Q

Which of the 2 thyroid hormones has higher affinity to transport proteins?

A

Thyroxine (T4)

146
Q

This is considered as the active thyroid hormone

A

Triiodothyronine

147
Q 
The peripheral deiodinase is found in the following organs except:
A. Pituitary
B. Parathyroid gland
C. Liver
D. Kidneys
E. NOTA
A

B. Parathyroid gland

148
Q

The sequential steps to Thyroid Hormone Biosynthesis

A

Iodide trapping > Oxidation of Iodide to Iodine > Organification/Iodination of Tyr residues in thyroglobulin > Coupling/ Conjugation

149
Q 
Which of the following is not a peptide hormone?
A. Insulin
B. PTH
C. Angiotensin
D. LPH
E. NOTA
A

E. NOTA

150
Q

This is the 15 hydrophobic amino acids at the N-terminal of the insulin

A

Leader sequence/ signal sequence

151
Q

In the ER, removal of the signal sequence in insulin biosynthesis will result to the product:

A

preinsulin

152
Q

The 2 amino acids in the site-specific cleavage sites of proinsulin

A

Arginine and Lysine

153
Q 
How many amino acids form the A and B chain of insulin, respectively?
A. 20, 31
B. 21, 30
C. 22, 33
D. 23, 40
A

B. 21 - A chain; 30 - B chain

154
Q 
The intradisulfide chain of insulin is found at:
A. amino acid 5-15 of B chain
B. amino acid 7-14 of B chain
C. amino acid 19-20 of A chain
D. amino acid 6-11 of A chain
A

D. amino acid 6-11 of A chain

155
Q

Where are the interdisulfide chains of isulin found?

A
  • between amino acid 7 (B chain) and 7 (A chain)

- between amino acid 19 (B chain) and 20 (A chain)

156
Q

This conformation allows the formation of critical structures within insulin for it to reach maturity

A

INTRA and INTER chain disulfide links

157
Q

Primary gene product in PTH biosynthesis

A

Prepro-PTH

158
Q

Immediate precursor of PTH

A

Pro-PTH

159
Q

The synthesis and secretion of PTH are regulated by:

A

Plasma ionized calcium levels

160
Q

Calcium molecules attach to ________ in Parathyroid gland surface, which allows this protein to monitor and regulate the amount of calcium in the blood

A

Calcium-sensing receptor

161
Q

The full biologic activity site of PTH is numbered:

A

1-34 residue

162
Q

The region for receptor binding sites of PTH is numbered:

A

24-34

163
Q

The PTH site-specific cleavage sites are marked by which amino acids?

A

Arginine, Lysine and Valine

164
Q

Which cells of the kidney produce Renin?

A

Juxtaglomerular cells at the afferent arteriole

165
Q

Which of Angiotensin is a decapeptide or an octapeptide?

A 
Decapeptide = Ang I
Octapeptide = Ang II
166
Q

Which enzyme of the lungs cleaver Ang I to Ang II?

A

Angiotensin Converting Enzyme

167
Q

How does Angiotensin II stimulate aldosterone

synthesis

A

Activates cAMP to increase conversion of cholesterol to pregnenolone via Cyt 11A1 and conversion of corticosterone to 18-hydroxycorticosterone via 18-hydroxylase

168
Q

Which alpha-2-globulin produced by the liver is cleaved by a proteolytic enzyme from the kidneys in response to decreased blood pressure?

A

Angiotensinogen (alpha-2-globulin produced by the livers)

Renin (proteolytic enzymes produced by the kidneys)

169
Q

Class of anti-hypertensive drugs: Captopril, Lisinopril

A

ACE-inhibitors

170
Q

Class of anti-hypertensive drugs: Losartan

A

Angiotensin II receptor blockers

171
Q

The long polypeptide chain, located in the anterior and intermediate lobes of the pituitary, that consists of peptides that act as hormones and neurotransmitters

A

Proopiomelanocortin

172
Q

Hormones that come from POMC

A

ACTH, LPH, MSH

173
Q

Neurotransmitters that come from POMC

A

Enkephalins and Endorphins

174
Q

POMC has how many amino acids?

A

285

175
Q 
Which of the following does not have POMC? 
A. brain
B. placenta
C. reproductive tract
D. GIT
E. lungs
A

None of those

176
Q

The amino-terminal fragment of POMC produces which Hormone?

A

gamma-MSH

177
Q

What hormone and peptide is generated from cleavage of ACTH?

A

alpha-MSH: hormone

Corticotrophin-like Intermediate Peptide (CLIP): peptide

178
Q

Which POMC fragment is the source of β-MSH

A

β-Lipotropin cleaved to form the C-terminal of γ-Lipotropin

179
Q

Cleavage of β-Lipotropin fragments will produce

A

γ-Lipotropin and β-Endorphin

180
Q

β-Endorphin is the source of which neurotransmitter?

A

Met-enkephalin

181
Q 
Which facilitates the proximation of disulfide chains of
active insulin?
a. Leader sequence
b. C peptide
c. Disulfide bonds itself
d. Formation of pro-insulin
A

d. Formation of pro-insulin

BIOCHEMISTRY MED1 (6 decks)

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