Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biochem Winter 2012 > Biochem Hormone Action 2 > Flashcards

Biochem Hormone Action 2 Flashcards

(77 cards)

Start Studying
1
Q

How do you define potentcy

A

Graph with hormones with different potencies for a R or receptors with different potetcies for a hormone

within a class of hormones, different lignad molecules may have different POTENCIES, represented by EC50 values

The -log[hormone] at which 50% maximal response is elicited

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

If ther eis higher potentcy, is midpoint (EC50) increacing potency to left or righ?

A

Left!

Need lower concentration to elicit 50% maximal response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what happens if constant concentrtion of an ANTAGONIST is added?

A

the binding curve for the hormone (agonist) will shift to the RIGHT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you define EFFICACY on graph

Agonist vs PARTIAL AGONIST

A

Height of response (maximum is 100%)

Agonist will hve response with 100% efficacty (height of response)

PARTIAL AGONIST which only have 50% maximal response, or 50% efficacy (regardless of hormone concentration)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Efficacy vs Potency

A

Efficacy = height

Potency = midpoint EC50 (concentration of hormone required for half-occupancy of receptor)
depends on both affinity and efficacy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the differnt kinds of Regulations of Receptors (3)

A

Down Regulation

Covalent Modification

Up Regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Down regulation

A

Desnsitization- Ineternalization of R

loss of receptor number from pPM by sequestration. This change results in DESENSITIZATION of biological response to addition of more agonist.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

examples of hormones that down regulate receptors

A 
Insulin
Glucagon
TRH
GH
LH
FSH
catecholamines
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Covalent modification of the receptor . Example?

A

Desensitization- frequely Phosphorylation

No change in R number and no translocation occurs.

Hormone binding and effector activaiton systems are uncooupled by covalent modification

I.E. Beta Adrenergic system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Up Regulation

A

Angiotensin II and PROLACTIN

increase their R number as R on the cell surface become occupied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Types of Hormone/Receptor/Diseases

A

Abnormal Receptor Regulation

Inadequate production of hormone

Antibodies directed against a specific hormone

No hormone binding to the R can be detected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are examples of Antibodies directed against specific hormone

A

Graves Disease
Acanthosis Nigrans (insulin resistant)
Myasthenia Gravis
Asthma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Graves Disease

A

Ab stimulates TSH R

Hyperthyroidism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Acanthosis Nigrans

A

Ab blocks insulin binding

insulin resistant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Myasthenia Gravis

A

Ab enchances turnover of Ach R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Asthma

A

Ab blocks Beta-Adrenergic binding to R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Examples of diseases where there is abnormal Receptor Regulation (2)

A
  1. Obesity - insulin binding is decreased

2. Diabetes mellitus- some form of NIDDM, TYpe II. Insulin binding is decreased; receptor down regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Examples of Disease where THERE IS INADEQUATE PRODUCTION OF HORMONE (4)

A
  1. Diabetes Mellitus (insulin-dependent form)
  2. Dwarfism- Deficiency f GH or somatotropin
  3. Gigantism, acromegaly- Excess secretin of GH
  4. Familial Neurohypophyseal diabetes insipidus (FNDI)- mUtations in vasopressin prohormone decrease VP syntehsis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

FNDI

A

mutations in vasopressin prohormone decreases VP synthesis

-due to inadequate production of hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Diseases where NO HORMONE BINDING TO THE RECEPTOR CAN BE DETECTED (receptor deficiency) (2)

A
  1. congenital neprhogenic diabetes insipidus

Pseudohypoparthyroidism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Congenital Neprhogenic Diabetes Insipidus

A

ADH receptor deficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Pseudohypoparathyroidism

A

PTH receptor deficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Classification of hormones by mechanism of action (2)

A

Hormones that bind to intracellular receptors

Hormones that bind to cell surface receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What kind of hormones bind to intracellular receptors?

A 
Usually Steroids
estrogen
glucocorticoids
mineralcorticoids
progestins
calcitrol (vit D)
andorgens
thyroid hormones (T3 and T4)
Retinoids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
What kind of hormones bind to cell-surface receptors (4)
1. 2nd messenger is cAMP 2. 2nd messenger is Ca2+ and Phosphatidylinositase 3. Intracellular effect is a kinase or phosphatase 4. Messenger is NO
25
Types of intracellular hormones (general) 3
Steroids Iodothryonines REtinoids
26
Types of cell surface hormones (general) 4
Polypeptids porteins glycoporteins catecholamines
27
Solubility of nuclear vs PM hormone
Lipophilic vs hydrophilic
28
PM transport protein needed in nuclear or PM?
nuclear- yes PM- some
29
Mediator of nuclear vs PM
nuclear- receptor-hormone complex PM cAMP, P-inositides, kinases, Ca2+ , etc
30
Mechanism of action of Intracellular (nuclear R) Hormones
1. Hormone delivery to cell passes membrnaes 2. binds receptor in nucleus 3. Activates gene Transciption 4. Protein/enzyme levels increase
31
Do steroid hormones need to be bound to carrier when passing PM?
NO! b/c lipohphilic
32
What happens when steroid-type hormone binds to an intracellular R ?
intracellular R changes conformation- to homodimer or heterodimer Complex binds to HRE (hormone response element)
33
What happens when hormone-receptor complex binds to HRE
complex binds to specific sequence which results in the Tx of a limited set of genes containing the right upstream regulatory elemnts
34
Three features of Cell Surface Receptor Binding/Cascade
Amplification Reversibility Rapidity
35
How many subunits is the G protein made up of?
three! Alpah, beta, gamma (different combinations of different types)
36
In the "resting state", the trimeric Gs protein has what bound to it? GTP or GDP?
GDP
37
upon interaction wih occupied R, Gs protein does what
exchanges GDP for GTP, it dissociates and alpha,s-GTP subunits is then capable of activiating the cyclase
38
How is this system shut off?
By hydrolysis of GTP to GDP by slow, intrinsic GTPase actiity of alpha-s prtein
39
what has GTPase activity>
alpha-s, reforms Gs protein with GDP bound to alpha subunit
40
What protein speeds up process of GTP inactivation?
GAP GTPase activating protein, speeds up process by increasing rate of GTP hyrolysis noe that alpha-i alos has intrinsic GTPase activity
41
What is GNEP?
guaninie nucleotide exhchange protein protein that catalyses reactivation of alpha-i, wich requires an exchange of GTP for GDP
42
Summary of events for second messenger of cAMP
Events coupled to G-protein 1. hormone binds to 7-serpentine R 2. The R activates a G-protein by GTP exchange 3. Activated alpha-subunit activates adenylyl cyclase 4. Adenylyl cyclase produces cAMP form ATP 5. cAMP activates protein kinase A (and others)
43
What is the effect of Cholera Toxin?
it activates G-alpha-s (inhibits GTPase) irreversably activatves ADENYLATE CYCLASE by preventing GTAse activity of G-alpha-s subunit --> increase cAMP activity --> activates PROTEIN KINASE
44
What are clinical effects of Cholera Toxin
Diarrhea! stimulation of active transprot which leads to massive loss of Na ion and water by gut
45
What is the biochemical cause of cholera toxin
ADP-ribosylation on Arg residues of the G prtein whcih the NAD moleucle provides the ADP-ribose Cholera = CS = cas (alpha s)
46
What happns when ADP is ribosylated Gs
GTPase activity is inactivated Gs constantly activates Adenylate Cyclase
47
What is the cause of Pertussin Toxin
inhibits G-alpha-i (blocks GTP on
48
What is clinical effects of Pertussin Toxin
DIAHHREA! irreversibily activates adenylate cyclase by promoting ADP-ribosylation of alpha-i, which prevents alpha-i subunit form being activated pertussin = pi (for alpha i)
49
What are initiating signal (hormones) for G-alpha-S class? Downstream signal
Beta adrenergic amines glucagon parathyroid hormone (PTH) others Dwnstrm signal: Stiulate Adenylate cyclase
50
What hormones serve as initiating signal for G-alpha-i? Whas is the downstream signal
Acetycholine alpha-adrenergic amines NTs Downstream sgl: Inhibits adenylatec cyclase
51
What are initiating signals of G-alpha-q? Downstream signal?
Acetylcholine alpha-adrenergic amines many NTs Downstream: Increases IP3 and intracellular Ca
52
What are initiating factor of G-alpha-t
Photons Stimulates cGMP phosphodiesterase
53
G alpha 13
Thrombin Stimulates Na/ H exchange
54
Describe activatino of protein kinase A (PKA or camp-dependent protein kinase)
PKA is activated by any mechanism that activates cAMP | CaMP binds to regulatory subunit and causes dissociation of catalytic subunit of PKA
55
Function of PKA
phosphorylates a wide variety of proteins: (enzymes, membrane proteins, nuclear proteins) Residues that are phosphorylatd are Ser or Thr residues (NOT tyrosine)
56
How can PKA system be turnef OFF?
cyclica AMP PHOSPHODIESTERASE
57
what kind of agents inhibit phosphodiesterase?
METHYLXANTHINES like coffee or theophylline) amplifies response by preventing or slowing the destruction of cAMP treats asthamticsby raising intracellular cAMP which leads to relaxation of SM
58
How can the adrenergic receptor be "desensitized"
by phosphoyraltion by a specific kinase, BARK for beta adrenergic receptor kinase B-arrestin then binds to this phosphoyralted domain
59
Process if Epinephrine is stimulus
B-adrenergic R Gs Ad Cyclase Glycogen breakdown
60
Serotonin
Serotonin R Gs Ad cyclase Behavrioal sensitization and learnign in APLYSIA
61
Light
rhodopsin Transducin cGMP PDE Visual excitation
62
Odornats
olfactory R G olf Ad cyclase olfaction
63
fMET
chemoatactic R Gq PLC Chemotaxis
64
Ach
Muscarinic R Gi K+ channels Slowing of pacemaker activity
65
What does Ras do?
Regulates CELL GROWTH through serine-threonine protein kinases
66
What does Rho do?
REORGANIZES CYTOSKELETON through serin-theronine protein kinases
67
What does Arf do?
Activates ADP-ribosyltransferase of the cholera toxin A subunis; regulates VESICULAR TRAFFICKING pathways; activates phospholipase D
68
What does Rab do?
Plays a key role in SECRETORY and ENDOCYTOTIC pathways
69
What does Ran do
Functions in the TRANSPORT of RNA and protein into and out of nucleus
70
What is neurofibromatosis
variety of benign and malignant tumors of CNS and PNS dominantly inherited genetic disorder
71
cuause of Neurofibromatosis
deletion or loss of function mutation in the nfl gene
72
What are clinical signs
cafe au lait macules (spots)
73
What is Neurofibromin
GTPase activating protein (GAP) for Ras (and other smll G-proteins)
74
What happens with loss of neurogbromin?
loss of GTPase activity which inactivates Ras and tehrefore Ras stays on in its GTP-bound form
75
What is Nf2?
tumor suppressor gene associated with neurofibromatosis
76
Describe mechanism of hormones that use Ca or phosphatidylinostides (or both)
1. hormone binds to 7 TM serpentine 2. Receptor activates a G-protein by GTP exchange 3. activated alpha-subunit activates PLC 4. Two second messengers are produced 5/ Protein Kinase C is activated

Biochem Winter 2012 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions