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POM| Molecular Biology of The Cell > Cell Signalling > Flashcards

Cell Signalling Flashcards

1
Q

Why do cells need to communicate?

A
  • Process information - sensory
  • Self-preservation - reflexes
  • Voluntary movement
  • Homeostasis
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2
Q

Which cells secrete glucagon?

A

α cells of Islet of Langerhans in pancreas

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3
Q

In response to what is glucagon secreted and what does it do?

A

In response to hypoglycaemic features, stimulates glycogenolysis and gluconeogenesis

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4
Q

What is endocrine signalling?

A

Hormone travels within blood vessels to acts on a distant target cell

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5
Q

What is paracrine signalling?

A

Signalling molecules act on an adjacent cell

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6
Q

Insulin inhibiting glucagon secretion is an example of what type of signalling?

A

Paracrine signalling

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7
Q

Adrenalin acting on the trachea is an example of what type of signalling?

A

Endocrine signalling

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8
Q

Glucagon and insulin acting on the liver is an example of what type of signalling?

A

Endocrine signalling

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9
Q

Nitric oxide produced by endothelial cells causing vasodilation is an example of what type of signalling?

A

Paracrine signalling as they act on the nearby smooth muscle cells

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10
Q

What is signalling between membrane attached proteins?

A

Plasma membrane proteins on adjacent cells interacting

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11
Q

Hepatitis C detected are recognised by which cells in the bloodstream?

A

Antigen presenting cells (APC)

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12
Q

Osteoclast activating factors produced by adjacent osteoblasts is an example of what type of signalling?

A

Paracrine signalling

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13
Q

What happens after APC recognised the pathogen?

A

APC expressing major histo-compatibility (MHC) class II molecules on surface after digesting the pathogen

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14
Q

MHC II interacts with what to alert the lymphocytes?

A

T-cell receptor (TCR)

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15
Q

What type of signalling occurs between APC and T-lymphocyte?

A

Signalling between membrane attached proteins - Class II MHC and TCR

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16
Q

Interaction of HIV GP120 with CD4 receptors of T cells is an example of what type of signalling?

A

Signalling between membrane attached proteins

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17
Q

Bacterial cell wall components interact with toll-like receptors on haematopoietic cells in what type of signalling?

A

Signalling between membrane attached proteins

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18
Q

What is autocrine signalling?

A

Signalling molecule acts on same cell

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19
Q

What cascade of reactions occur after TCR activation?

A

Expression of IL-2 receptors → Secretion of IL-2

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20
Q

What types of signalling are involved in IL-2 secretion by T cells?

A

Autocrine and paracrine signalling - IL-2 binds to IL-2 receptors on same cell and adjacent cells

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21
Q

What type of signalling is involved in positive and negative self-feedback on neurones?

A

Autocrine signalling

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22
Q

ACh providing positive feedback for the presynaptic neurone is an example of what type of signalling?

A

Autocrine signalling - ACh binds to presynaptic M2-muscarinic receptors to promote NT secretion

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23
Q

Which type of signalling is used by the growth factor TGFβ?

A

Autocrine signalling as it promotes mitogenesis of the same cell

24
Q

What are the 4 main steps of neurotransmission?

A
  1. Propagation of AP
  2. NT release from vesicles
  3. Activation of postsynaptic receptors
  4. Disposal or recollection of NT
25
Q

What are the 4 main types of receptors?

A
  • Ionotropic
  • G-protein coupled
  • Enzyme-linked
  • Intracellular
26
Q

Identify the activation and function mechanisms of G-protein coupled receptors?

A

Ligand binding → activates intracellular G-protein

27
Q

Identify the activation and function mechanisms of ionotropic receptors?

A

Ligand binding → opens ion permeable pore traversing the membrane

28
Q

Identify the activation and function mechanisms of enzyme-linked receptors?

A

Ligand binding → receptor clustering → activates internal enzymes

29
Q

Identify the activation mechanism of intracellular receptors?

A

A membrane permeable ligand binds to receptor inside cell

30
Q

What type of receptor is Nicotinic ACh receptor?

A

Ionotropic

31
Q

What is the activator ligand, location and physiological effect of Nicotinic ACh receptor?

A

Ligand: ACh
Location: Skeletal muscle
Physiological effect: Muscle contraction

32
Q

What is the action mechanism of GPCR?

A

GPCR activated by ligand binding → changes conformation of receptor binding to G protein → GTP replaces GDP binding to G protein → G protein dissociates into α and βγ subunits → Gα:GTP complex acts on the target protein → GTP dephosphorylated forcing Gα to couple back with Gβγ

33
Q

What are the components of heterotrimeric G protein?

A

α, β and γ subunits

34
Q

Why is the protein Gs named that way?

A

(s)timulates adenylyl cyclase

35
Q

Why is the protein Gi named that way?

A

(i)nhibits adenylyl cyclase

36
Q

What happens when adenylyl cyclase is stimulated?

A

converts ATP to cAMP → cAMP activates protein kinase A (PKA)

37
Q

What happens when adenylyl cyclase is inhibited?

A

PKA level reduced

38
Q

What is an example of GPCR activating Gs?

A

β1-adrenergic receptor

39
Q

What is an example of GPCR activating Gi?

A

M2-muscarinic receptor

40
Q

Which protein does Gq act on?

A

stimulates phospholipase C (PLC)

41
Q

What happens when PLC is stimulated?

A

Converts PIP2 to IP3 and DAG → IP3 stimulates Ca2+ release and DAG activates PKC

42
Q

Which type of G protein couples with AT-1 (angiotensin) receptor?

A

Gq protein

43
Q

Which ligand binds and activates the CD220 receptor?

A

Insulin - resulting in glucose uptake by the cell

44
Q

What type of receptor is CD220?

A

Enzyme-linked receptor

45
Q

Which ligands bind to the ErbB receptor?

A

Epidermal growth factor and Transforming growth factor β

46
Q

What is the physiological effect of ErbB when ligand is present?

A

Cell growth, proliferation

47
Q

What are the 2 types of intracellular receptors?

A

Type 1 - Cytoplasmic
Type 2 - Nuclear

48
Q

Which type of intracellular receptors is associated with heat shock proteins (chaperone molecules, hsp)?

A

Type 1 - Cytoplasmic

49
Q

What is the action mechanism of cytoplasmic intracellular receptors?

A

hormone binds to receptor → hsp dissociates → 2 hormone bound receptors form a homodimer → The homodimer translocates to the nucleus binding to DNA

50
Q

What is the action mechanism of nuclear intracellular receptors?

A

hormone binds to receptor → transcriptional regulation

51
Q

What type of receptor is glucocorticoid receptor?

A

Type 1 intracellular receptor

52
Q

Which ligands bind to glucocorticoid receptor?

A

Cortisol and Corticosterone

53
Q

What are the physiological effects of active glucocorticoid receptors?

A

Reduced immune response and increased gluconeogenesis

54
Q

What type of receptor is thyroid hormone receptor?

A

Type 2 intracellular receptor

55
Q

Which ligands bind to thyroid hormone receptor?

A

T3 (thyroxine) and T4 (triiodothyronine)

56
Q

What are the physiological effects of active thyroid hormone receptors?

A

Growth and development

POM| Molecular Biology of The Cell (10 decks)

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