7: Cell Communication 1 Flashcards

1
Q

What allows communication between cells?

A

Gap junctions

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2
Q

What are gap junctions made up of?

A

Connexin proteins

  • Gated by Ca2+, voltage and membrane potential, also phosphorylation
  • Referred to as ‘electrical synapses’
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3
Q

What are the two main classes of receptor and messenger/ligand?

A
  • Water soluble chemical messengers

- Lipid-soluble chemical messengers

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4
Q

How does water-soluble chemical messengers work?

A

signals can’t diffuse through the plasma membrane, so they bind to plasma membrane receptors. Activate specific cellular signalling

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5
Q

How do lipid-soluble chemical messengers work?

A

Diffuse through the plasma membrane and bind intracellular receptors located in the cytoplasm or nucleus. Alters transcription

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6
Q

What are the 4 types of plasma membrane receptors

A
  1. Ion channel linked receptors aka ionotropic receptors
  2. G protein coupled receptors (GPCR) aka metabotropic
  3. Enzyme linked receptors
  4. Regulated intramembrane proteolysis
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7
Q

Draw/label an ion channel linked/ionotropic receptor

A

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8
Q

Draw/label a G protein coupled receptor/metabotropic receptor

A

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9
Q

Draw/label an enzyme linked receptor

A

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10
Q

What are some chemical messengers/signals for ion channel linked receptors

A

Neurotransmitters (acetylcholine, glycine, GABA, glutamate), purines, serotonin

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11
Q

What are some signals for enzyme linked receptors

A

Nerve growth factor, growth hormone, insulin

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12
Q

What are some signals for regulated membrane proteolysis

A

Amyloid precursor protien, Notch

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13
Q

Describe the G protein signalling pathway (diagrams will help as well)

A
  1. Ligands binds to receptor, which activates it
  2. Receptor interacts with the G protein to promote a conformational change and the exchange of GDP for GTP
    GEFs facilitate the dissociation of GDP and the binding of GTP
  3. G protein dissociates from the receptor
  4. alpha GTP and beta-gamma subunits dissociate

(look though slides)

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14
Q

What are the two ways that ion channels are able to be activated

A

Indirectly via GPCRs or

Directly by neurotransmitters

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15
Q

Describe how ion channels can be activated indirectly via GPCR

A
  1. Neurotransmitter binds
  2. G protein is activated
  3. G protein subunits or intracelular messengers modulate ion channels
  4. Ion channel opens
  5. Ions flow across membranes

(look through slides for full detail)

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16
Q

Describe how ion channels are activated by neurotransmitters

A
  1. Neurotransmitter binds
  2. Channel opens
  3. Ions flow across membrane
17
Q

Signalling through GPCRs -example 1: GPCRs coupled to Gαs, the effector adenylyl cyclase and cAMP

A

G protein complex
-Gαs

Effector
-Adenylyl cyclase

Second messenger
-cAMP

Cellular effect
-PKA phosphorylates target proteins

18
Q

Signalling through GPCRs: activation of kinase A (PKA)

A

G protein complex

19
Q

Switching off GPCR signal transduction pathways

A

slides