Basics Flashcards

1
Q

Therapeutic Index =

A

Maximum non-toxic dose . minimum effective dose /

TD50/ ED50

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2
Q

Popper’s law

A

Statements can only be falsifiable

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3
Q

Carson’s consolation

A

No experiment is ever useless

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4
Q

4 types of receptors:

A

LGIC, GPCR, Kinase-linked + related & I.C./ nuclear related receptors

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5
Q

An example of a pentamer, tetramer and trimer LGIC

A

Cys-loop family, glutamate, P2X

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6
Q

3rd I.C. loop of GPCR’s is critical for

A

Interaction with I.C. G-proteins

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7
Q

Domains of Kinase-linked receptors

A

Extracellular ligand-binding and intracellular effector

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8
Q

Common mech of action for kinase-linked receptors

A

Dimerisation

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9
Q

Outline tyrosine kinase receptor activity

A

Auto-phosphorylation of tyrosine residues on each cytoplasmic domain -> act as binding sites -> leads to binding of intracellular proteins (SH2 domain proteins) -> become phosphorylated and activated

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10
Q

Intracellular/ nuclear receptors are different from other receptors, how?

A

Soluble monomeric proteins that regulate gene transcription through dimeric form from ligand binding

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11
Q

Example of LGIC and mech of action

A

nAChR - ACh binds leading to conformational change so Na+/K+ ions flow in or out - coupling between receptor activation and response

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12
Q

LGIC time frame

A

~ 1 ms

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13
Q

Difference between glutamate LGIC and GABA/ glycine?

A

Cation v anionic chloride channels

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14
Q

Outline GPCR activation using Gs

A

(1) At rest the  subunit of the Gs-protein binds GDP
(2) When the receptor is activated, its affinity for Gs increases and
(3) it interacts with the Gs-protein. The  subunit catalyzes the exchange of GDP for GTP.
(4). The GTP-bound G-protein acts as the first messenger and interacts with an effeczor molecule
(e.g., an enzyme, in this case adenylate cyclase, or an ion channel etc.).
(5) The enzyme becomes activated producing cAMP. The G-protein also has GTPase enzymatic
activity, hydrolyzing GTP to GDP. (6). The GDP stays bound to the G protein, so the G protein
reverts to the resting state, stage (1). This switches off the G protein’s action.

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15
Q

Functions of Gs

A

activates adenylyl cyclase and Ca2+ channels

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16
Q

Functions of Golf

A

activates adenylyl cyclase in olfactory sensory neurons

17
Q

Gi

A

inhibitis acdenylyl cyclase and activates K+ channels

18
Q

Go functions

A

Activates K+ cnhannels
inactivates Ca2+ channels
activates PLC-beta

19
Q

Gt functions

A

activates cGMP phosphodiesterase in vertebrate rod photoreceptors

20
Q

Gq functions

A

activates PLC-beta

21
Q

What does PLC do?

A

Splits membrane phospholipid phosphatidylinositol biphosphate to InsP3 and DAG

22
Q

Outline insulin receptor function

A

Binding of insulin -> autophosphorylation of catalytic domains -> phosphorylates insulin receptor substrate - 1 (IRS-1) -> high affinity binding site for docking and activation of other signalling molecules and proteins

23
Q

Two stages of nuclease receptor response

A
  1. direct induction of a few genes (30-60 mins)

2. late/ delayed response -> induction of secondary regulatory gene