Introduction to Cell Signalling (Week 1)

Question 1

What is autocrine signalling?

Answer 1

Signalling molecules bind to receptors on the same cell that secreted them

Question 2

Example autocrine hormone name, cell that secretes it and pathway

Answer 2

Somatostatin
Secreted by D cells in gastric glands
Binds SST2 receptor which inhibits adenylyl cyclase decreasing cAMP and then HCl secretion

Question 3

Paracrine signalling

Answer 3

Signalling molecules excreted to extracellular space and bind adjacent cell without passing through the circulatory system

Question 4

Example paracrine molecule name, secretory cell and pathway

Answer 4

Histamine
Secreted by enterochromaffin-like cell in response to acetylcholine
Bind H2 receptors on parietal cells activating adenylyl cyclase which increases the number of proton pumps

Question 5

Endocrine signalling

Answer 5

signalling molecules are secreted from secretory glands into the bloodstream and activate a distant receptor

Question 6

Endocrine example molecule name, secreted from, and target

Answer 6

ACTH
Released from pituatary gland hypophyseal portal system
Kidneys

Question 7

Synaptic transmission

Answer 7

electrical signals being transmitted between electrically excitable cells (neurons/muscle cells)

Question 8

Why are neurons and muscle cells electrically excitable

Answer 8

They have many ion channels

Question 9

What do action potentials cause at the bouton

Answer 9

Opening of voltage gated ion channels and depolarisation of the membrane

Question 10

What does neuron membrane depolarisation cause

Answer 10

Opening of calcium channels

Question 11

What happens when calcium enters the synaptic bouton

Answer 11

It binds microtubules causing vesicles to be pushed to the synaptic cleft and exocytosis - release of neurotransmitters

Question 12

What do neurotransmitters bind on the post synaptic neuron

Answer 12

GPCRs leading to a ion channels opening and a new action poteintial

Question 13

Ligand-gated ion channel structure and function

Answer 13

Multiple protein subunits around a central channel. Change the polarisation of a cell

Question 14

G-protein coupled receptors structure and function

Answer 14

7-transmembrane polypeptide chain with extracellular N terminus and intracellular C terminus associated with a G protein system. Act through second-messenger activity

Question 15

Ligand-gated ion channel response time

Answer 15

Milliseconds

Question 16

Nicotinic acetylcholine receptor structure and function

Answer 16

5 subunit non-specific cation (positive) ion channel. Cholinergic neurotransmission

Question 17

GPCR response time

Answer 17

Seconds and effects last longer than ion channels

Question 18

Adrenaline binding beta2-adrenoreceptors

Answer 18

Conformational change
GDP attached to alpha G-protein replaced with GTP
GTP-G alpha cyclase moves to activate adenylyl cyclase
cAMP activates PKA leading to the inhibition of MLCK
Bronchodilation

Question 19

Adrenaline binding alpha2- adrenoreceptors

Answer 19

Conformational change
GDP attached to alpha G-protein replaced with GTP
GTP-G alpha cyclase moves to inhibit adenylyl cyclase
Less cAMP leads to relaxation of GI tract

Question 20

Adrenaline binding alpha1-adreoreceptors

Answer 20

Conformational change
GDP attached to alpha G-protein replaced with GTP
GTP-G alpha cyclase moves to activate phospholipase C which converts PIP2 to DAG and IP3
Less Ca2+ leads to vasoconstriction

Question 21

Kinase-linked receptor response time

Answer 21

Hours

Question 22

Nuclear receptor response time

Answer 22

Hours

Question 23

Nuclear receptor structure and function

Answer 23

Protein monomers that contain a DNA-binding domain. Control gene transcription

Question 24

What type of receptors are nicotinic

Answer 24

Cholinergic ligand-gated ion channels

Question 25

What type of receptors are muscarinic

Answer 25

Cholinergic GPCRs

Question 26

What physiological processes are enzyme-coupled receptors key in and why

Answer 26

Metabolism and growth
They are multi-faceted

Question 27

What type of receptors do steroids generally bind

Answer 27

Nuclear

Question 28

Steroids: lipophilic or hydrophilic

Answer 28

lipophilic/hydrophobic

Question 29

What type of receptors are linked with signal amplification by second messengers

Answer 29

GPCRs

Question 30

What protein transports steroids through the blood

Answer 30

Albumin

Question 31

Explain signal amplification

Answer 31

Adenylyl cyclase: ATP -> cAMP
Each cAMP activates a kinase
Each kinase phosphorylates many enzymes
Each enzyme produces many products

Question 32

How many transmembrane domains do GPCRs have

Answer 32

7

Question 33

Define a second messenger

Answer 33

A signal molecule which acts as a result of another pathway but does not change another molecule

Question 34

Define affinity

Answer 34

The tendency of a (signalling) molecule to bind its receptor