Intro to Biological Signalling

Question 1

What are the 3 types of intracellular signalling?

Answer 1

Paracrine = in tissues, local mediators to target cells
Synaptic = in nerve cells, neurotransmitters
Endocrine = in bloodstream, hormones

Question 2

What molecules can pass through the membrane and so don’t require cell surface receptors?

Answer 2

Hydrophobic

Question 3

Receptor

Answer 3

A molecule that recognises specifically a 2nd molecule (ligand)/family of molecule, and which (in response to ligand binding) brings about regulation of a cellular process

Question 4

In the unbound state, the receptor is functionally ……

Answer 4

Silent

Question 5

Ligand

Answer 5

Any molecule that binds specifically to a receptor site

Question 6

Cardiac pacemaker cells

Answer 6

Noradrenaline = beta-1 adrenoceptors = increase HR
Acetylcholine = M2 muscarinic receptors = decrease HR

Question 7

What drug acts as a nicotinic acetylcholine receptor?

Answer 7

Suxamethonium = muscle relaxant, channels open, sodium in

Question 8

What drug acts as a muscarinic acetylcholine receptor?

Answer 8

Atropine, increases HR (because ACh decreases HR)

Question 9

Role of receptors

Answer 9

Neurotransmission
Control gene expression
Release intracellular Ca stores
Signalling by hormones

Question 10

What has a higher affinity of binding, enzymes to A.S. or ligands to ligand binding site?

Answer 10

Ligand

Question 11

Describe signalling via tyrosine kinase linked receptors?

Answer 11

E.g. insulin + growth factors
Agonist binds = auto phosphorylation = receptors activated
Conformational change = receptors become dimers, activated enzyme released
Transducer phosphorylated = sets of multiple signalling pathways