Cell Signalling

Question 1

What is autocrine intercellular signalling?

Answer 1

Cell targets itself.
Synthesis of a soluble ligand that is subsequently released.

Question 2

What is paracrine intercellular signalling?

Answer 2

Cell targets a nearby cell.
Signalling cell generates and propagates a signal that results in a mediator being released.

Question 3

What is endocrine intercellular signalling?

Answer 3

A cell targets a distant cell through the bloodstream.
Hormone dependent mechanism

Question 4

What is exocrine intercellular signalling?

Answer 4

Exocrine glands secrete substances onto an epithelial surface via a duct.

Question 5

What is juxtacrine intercellular signalling? (AKA direct signalling)

Answer 5

Involves the communication between cells that are in direct contact with each other.

Question 6

What organ is both an exocrine and endocrine gland?

Answer 6

Liver

Question 7

What receptor causes a protein conformational change, causing the channel to open allowing ions to move in or out?

Answer 7

Ligand-gated ion channel receptor

Question 8

What receptor triggers a series of events which induce the binding of G-protein and the modulation of second messengers.

Answer 8

G-protein coupled receptors

Question 9

What receptor phosphorylate their protein substrates, and are they receptor for many polypeptide growth factors such as insulin?

Answer 9

Kinase-linked receptors

Question 10

What receptors are intracellular and respond to many hydrophobic ligands which cross the plasma membrane?

Answer 10

Nuclear receptors

Question 11

Which receptor has the shortest signalling pathway?

Answer 11

Ligand-gated ion channel receptors (milliseconds)

Question 12

What receptor has the longest time signalling pathway?

Answer 12

Nuclear receptors (hours/days)

Question 13

What are signalosomes?

Answer 13

Large supramolecular complexes

Question 14

What is S-Adenosylmethionine (SAM) required for?

Answer 14

SAM is required for DNA methylation

Question 15

In which biological cycle is SAM synthesized?

Answer 15

Methionine cycle

Question 16

What is the consequence of low SAM levels on DNA?

Answer 16

Low global DNA hypomethylation

Question 17

What is a way to measure cell signalling?

Answer 17

Immunoblotting (Western blotting)

Question 18

What is a key feature of kinase cascades in signal transduction?

Answer 18

Kinase cascades allow different signals to input a pathway at different places.

Question 19

How do kinase cascades allow signal amplification?

Answer 19

Amplify signals by sequentially activating multiple downstream kinases.

Question 20

Do signaling cascades involve both kinases and phosphatases?

Answer 20

Yes. Kinases and phosphatases work together.

Question 21

What role do phosphatases play in kinase cascades?

Answer 21

Phosphatases can turn off or down-regulate kinase cascades by removing phosphate groups.

Question 22

How can kinase cascades increase specificity in signaling?

Answer 22

Specificity can be increased when kinases are structurally organized within the cascade.

Question 23

What are the major types of cell signal receptors?

Answer 23

Ligand-gated ion channels
G-protein coupled receptors (GPCRs)
Kinase-linked receptors
Nuclear receptors

Question 24

Can GPCRs signal from endosomes after receptor internalisation?

Answer 24

Yes

Question 25

What is an example of a transmembrane receptor capable of activating signal transduction pathways

Answer 25

Integrins

Question 26

What factors can influence the cellular outcomes of signal transduction?

Answer 26

Cellular outcomes can rely on the signalling molecule lifetime, the type of target cell, and tissue dependency.

Question 27

True or false. Receptors cannot signal from lipid rafts.

Answer 27

False. Some receptors can signal from lipid rafts.

Question 28

What are GPCRs and what is their role in cell signalling?

Answer 28

GCPRs are G protein-coupled receptors that mediate signaling by activating G proteins upon ligand binding.