Biochemical signalling

Question 1

What are first messengers?

Answer 1

-produced in 1 cell + released by diffusion or exocytosis
-then detected by target cell by surface or intracellular receptors

Question 2

What are the properties of chemical signals?

Answer 2

-unique - only detected by correct receptors
-most have no biochemical function
-usually small enough to travel easily
-synthesised, altered or released quickly so signalling switched on rapidly
-degrade or re-sequestered quickly so signalling ends quickly

Question 3

What are the 2 signalling pathways?

Answer 3

-endocrine signalling - over a long distance e.g hormones
-paracrine signalling - over a short distance e.g local mediators

Question 4

What enables the specificity of receptors?

Answer 4

Complex 3D protein shapes

Question 5

What mediates the affinity a receptor has for the signal?

Answer 5

Binding strength mediated by noncovalent bonds

Question 6

What are the ideal properties for receptors?

Answer 6

-high specificity
-high affinity
-low affinity if have a high amount of signal

Question 7

What happens when a receptor and ligand bind?

Answer 7

-binding causes a conformational change in receptor
-receptor is activated + can ‘convert’ the extracellular change into an intracellular one
-induces a change in cytoplasm

Question 8

What are ligand gated ion channels?

Answer 8

-multi subunit transmembrane protein
-forms a pore through which specific ions can pass

Question 9

Where are ligand gated ion channels frequently found?

Answer 9

-at neuronal synapses
-rapidly respond to neurotransmitter ligands

Question 10

Describe nicotinic acetylcholine receptors

Answer 10

-ligand binding causes rotation of subunits
-opens constriction (gate) in channel
-allows sodium ions to enter cell