General Principles of Cell Communication & Intracellular Signalling Flashcards Preview

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Flashcards in General Principles of Cell Communication & Intracellular Signalling Deck (21)
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1
Q

What is endocrine signalling?

A

The process by which hormones are released and reach their targets by being released into the bloodstream, reaching targets that can be far from the gland.

2
Q

What is paracrine signalling?

A

The process by which cells communicate with other nearby cells (without the use of gap junctions) by releasing hormones that travel by diffusion to their targets.

3
Q

What is autocrine signalling?

A

The process by which a cell releases a hormone that binds to autocrine receptors on the same cell, inducing a response.

4
Q

What are the 4 main receptor types?

A

1 - Ligand-gated ion channels (ionotropic receptors)

2 - G-protein-coupled receptors (metabotropic receptors)

3 - Kinase-linked receptors

4 - Nuclear receptors

5
Q

What is an example of an antagonist to nicotinic AChRs?

A

Curare

6
Q

What is an example of an antagonist to muscarinic AChRs?

A

Atropa Belladonna alkaloids

7
Q

Give 3 examples of where nicotinic AChRs can be found in the nervous system.

A
  • At all autonomic ganglia between pre- and post-ganglionics.
  • At parasympathetic postganglionic ganglia.
  • At the NMJ.
8
Q

Give 4 examples of effects of stimulation of muscarinic AChRs.

A
  • Bradycardia
  • Salivation
  • Bronchospasm (narrowing of bronchi)
  • Mydriasis
9
Q

Which type of intermolecular interactions must break to open nicotinic AChRs?

A

Hydrophobic interactions.

10
Q

Which ions move across open nicotinic AChRs? In which direction do they move?

A

Na+ in

K+ out

11
Q

Which is the largest family of membrane receptors?

A

G-protein-coupled receptors (~40% drugs on market target these).

12
Q

Name one function that can be carried out by beta gamma subunits of an activated g protein.

A

Modulation of Ca2+ channels.

13
Q

Name two functions that can be carried out by an alpha subunit of an activated g protein.

A

Activation of adenylyl cyclase to convert ATP into cAMP.

Activation of phospholipase C.

14
Q

Describe the hormonal regulation pathway of glycogen metabolism.

A

In the liver:

  • cAMP activates protein kinase A
  • Protein Kinase A deactivates P-Glycogen synthase
  • Protein kinase A converts inactive phosphorylase kinase into inactive glycogen phosphorylase b
  • Phosphorylase kinase-P converts inactive glycogen phosphorylase b into active glycogen phosphorylase a
  • Active glycogen phosphorylase a converts Glycogen(n) + Pi -> Glycogen(n-1) + Glucose-1-Phosphate
15
Q

What is a Gq subunit?

A

A type of alpha subunit of a G protein that activates phospholipase C.

16
Q

What is a Gs subunit?

A

A type of alpha subunit of a G protein subunit that activates the cAMP-dependent pathway by activating adenylyl cyclase.

17
Q

Describe the pathway taken by phospholipase C.

A
  • PLC is converted into DAG and InsP3.
  • InsP3 causes Ca2+ release, causing a biological response
  • Ca2+ activates protein kinase C, causing a biological response.
18
Q

What is the difference between a kinase and a phosphatase?

A

A kinase adds phosphate whereas a phosphatase removes phosphate.

19
Q

Define Kd.

A

Dissociation constant:

The concentration of agonist when the receptors are half-maximally occupied.

Kd = [R][L]/[RL]

20
Q

Define EC50

A

The concentration of agonist that causes a half-maximal response.

21
Q

Describe the shape of a graph that shows log agonist against fraction of occupancy.

A

Sigmoid