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BMS03 > Chemical Signalling 1 > Flashcards

Chemical Signalling 1 Flashcards

1
Q

Describe the general steps of cell communication by extracellular signals

A
  1. Synthesis and release of signalling molecule by signalling cell
  2. Transport of signal to target cell
  3. Detection of incoming signal by a receptor on target cell/organelle
  4. Binding of signal to receptor = biological response
  5. Removal of signal = termination of response
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2
Q

Give three examples of hormones and growth factors

A

Any from:

Oestradiol
Progesterone
Growth hormone
Nerve growth factor
Epidermal growth factor
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3
Q

Give three examples of metabolic regulators

A

Any from:

Insulin
Glucagon
Adrenaline
Cortisol

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4
Q

Give three examples of neurotransmitter

A

Any from:

Glutamate
Acetylcholine
Dopamine
GABA
Opioids
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5
Q

Give three examples of inflammatory mediators

A

Prostaglandins
Thromboxanes
Cytokines

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6
Q

What are the four types of signalling molecules?

A

Hormones/growth factors

Metabolic regulators

Neurotransmitters

Inflammatory mediators

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7
Q

What are the three main types of signalling and what is this classification based on?

A

Endocrine

Paracrine

Autocrine

Based on distance over which the signals act

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8
Q

What is endocrine signalling?

A

Secretion of hormones into bloodstream

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9
Q

What type of organs/glands are involved in endocrine signalling?

A

Endocrine organs/glands

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10
Q

How far are the target cells from site of signalling molecule synthesis in endocrine signalling?

A

Up to a few metres

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11
Q

What are the steps of endocrine signalling?

A
  1. Stimulation of endocrine gland to synthesise and secrete hormone
  2. Hormone carried in bloodstream to target cells
  3. Hormone binds to and activates receptor to stimulate a biological response
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12
Q

What is paracrine signalling?

A

Signalling to adjacent cells

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13
Q

What is an example of paracrine signalling?

A

Transmission at neuromuscular junctions

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14
Q

How far apart are the cells involved in paracrine signalling?

A

A few microns/micrometres

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15
Q

What is autocrine signalling?

A

Signalling back onto the same cell

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16
Q

What is an example of autocrine signalling?

A

Any from:

Tumour cells

Certain growth factors

Autoreceptors (neurotransmitter release)

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17
Q

What are cell surface receptors?

A

Integral proteins which bind signalling molecules with high selectivity and high affinity

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18
Q

What are the three major classes of receptors?

A

Ionotropic

Metabotropic

Catalytic

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19
Q

Give an example of an ionotropic receptor

A

Nicotinic cholinergic receptor

Ionotropic glutamate receptor

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20
Q

What is another name for ionotropic receptors

A

Ligand-gated ion channels

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21
Q

What is another term for metabotropic receptors?

A

7 transmembrane spanning G-protein coupled receptors

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22
Q

Give an example of a metabotropic receptor

A

Glucagon receptor

Adrenaline receptor

(Beta adrenergic receptors)

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23
Q

What does RTK stand for?

A

Receptor tyrosine kinase

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24
Q

What kind of receptor is RTK?

A

Catalytic

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25
Q

Give an example of a catalytic receptor

A

Insulin receptor

Nerve growth receptor

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26
Q

What are the two types of intracellular signalling pathways?

A

Signalling cascades/adaptor protein scaffolds

Secondary messengers

27
Q

Which receptor uses signalling cascades/adaptor protein scaffolds?

A

RTK

28
Q

What type of receptor uses secondary messengers?

A

GPCR

29
Q

Give an example of an effector enzyme

A

Adenylyl cyclase

Phospholipase C

30
Q

Give an example of a second messenger molecule

A 
cAMP
cGMP
Arachidonic acid
Nitric oxide
IP3
DAG
31
Q

What second messenger does adenylyl cyclase produce?

A

cAMP

32
Q

What second messenger does phospholipase C produce?

A

IP3 (inositol 1,4,5-triphosphate)

OR

DAG (1,2-diacylglycerol)

33
Q

Where is the G-protein interaction domain on a 7TMGPCR?

A

Between the 5th and 6th transmembrane protein

34
Q

What is the main type of secondary protein structure present in a 7TMGPCR?

A

Alpha helix

35
Q

Where is the N-terminal of a 7TMGPCR?

A

Outside the cell

36
Q

Where is the C-terminal of a 7TMGPCR?

A

Inside the cell

37
Q

When is a G-protein active?

A

When bound to GTP

38
Q

What is a G-protein?

A

Molecular “switch” that carries information from receptors to effector enzymes

39
Q

How many subunits is the G-protein (involved in GPCR signalling) made up of?

A

3 (heterotrimeric)

40
Q

What are the steps in GPCR signalling?

A
  1. Hormone binds to receptor
  2. Inactive G-protein associates with receptor
  3. GTP is exchanged for the GDP (activation of G-protein)
  4. G-protein dissociates into alpha-GTP and beta-gamma subunits
  5. Alpha-GTP activates effector enzyme
  6. Effector enzyme produces second messenger
  7. GTP hydrolysed to GDP and G-protein complex reassociates; signalling ends
41
Q

What G-protein is associated with beta-adrenergic receptors?

A

Gs

42
Q

What G-protein is associated with cannabinoid (CB1) receptors?

A

Gi

43
Q

What G-protein is associated with M1 muscarinic (ACh/alpha-1 adrenergic) receptors?

A

Gq

44
Q

What effector enzyme is associated with beta-adrenergic receptors? What is the effect?

A

Adenylyl cyclase

Increase cAMP production

45
Q

What effector enzyme is associated with cannabinoid (CB1) receptors? What is the effect?

A

Adenylyl cyclase

Decrease cAMP production

46
Q

What effector enzyme is associated with M1 muscarinic (ACh/alpha-1 adrenergic) receptors? What is the effect?

A

Phospholipase C

Produce IP3 (release calcium from stores)

Produce DAG (activates PKC)

47
Q

What does IP3 trigger?

A

Release of calcium from stores

48
Q

What is the function of DAG?

A

Activate PKC

49
Q

What is the structure of PKA?

A

4 sub-units: 2 catalytic, 2 regulatory

50
Q

What does PKA stand for?

A

cAMP dependent protein kinase A

51
Q

What happens when cAMP and PKA bind?

A

PKA falls apart releasing catalytic subunits

52
Q

What occurs after the PKA catalytic subunits are released?

A

Serine/threonine phosphorylation

53
Q

What is the result of serine/threonine phosphorylation? (2)

A

Short term signalling actions (metabolic)

Phosphorylation of CREB

54
Q

What is CREB?

A

cAMP response element binding protein (transcription factor)

55
Q

What does CREB phosphorylation affect?

A

Affects glucose/glutamate transporters (regulating gene expression)

56
Q

What enzyme converts cAMP to 5’AMP?

A

Phosphodiesterase

57
Q

What is the function of phosphodiesterase?

A

Convert cAMP to 5’AMP

No binding to PKA therefore terminates response

58
Q

What type of receptor is stimulated in the “fight or flight” response?

A

Beta adrenergic

59
Q

What is the point in the “fight or flight” response?

A

Liberates glucose for respiration (more energy released)

More cAMP to stimulate more PKA

60
Q

What enzymes are stimulated in the “fight or flight” response?

A

(Adenylyl cyclase and PKA)

Glycogen phosphorylase kinase

Glycogen phosphorylase

61
Q

What enzyme is inhibited in the “fight or flight” response?

A

Glycogen synthase

62
Q

What does the stimulation of glycogen phosphorylase cause?

A

Increased glycogen degradation

63
Q

What does the inhibition of glycogen synthase cause?

A

Decreased glycogen synthesis

BMS03 (12 decks)

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