Cell Signalling

Question 1

Define extracellular mediator

Answer 1

An extracellular stimulus to a cell

Question 2

What kind of general affects can an extracellular mediator have on a cell after interacting with the plasma membrane?

Answer 2

Modifications of cellular metabolism, function, movement

Question 3

What kind of general affects can an extracellular mediator have on a cell after interacting with the nuclear membrane?

Answer 3

Modifications to gene expression, development

Question 4

How do hydrophobic signals interact with the plasma membrane?

Answer 4

Can easily cross it / diffuse across it due to being hydrophobic

Question 5

List three hydrophobic cell signals

Answer 5

Steroids, retinoids, thyroxine

Question 6

Steroids, retinoids and thyroxine are all examples of what?

Answer 6

Hydrophobic cell signals

Question 7

Compare the terms ‘endocrine’ , ‘autocrine’ and ‘paracrine’ when describing cell signals

Answer 7

Endocrine: Long range signals (usually blood borne hormones

Autocrine: Same cell signals (usually growth factors or cytokines

Paracrine: Short range signal from nearby cells (usually growth factors or cytokines)

Question 8

What general type of effects do hormones have on target cells?

Answer 8

Short-term metabolic effects

Question 9

What general type of effects do growth factors have on target cells?

Answer 9

Long-term proliferation/developmental effects

Question 10

What general type of effects do steroid hormones have on target cells?

Answer 10

Long term

Question 11

What distance do steroid hormones usually act at for cell signalling?

Answer 11

Autocrine (same cell)

Question 12

What kinds of pathways are GCPR involved in?

Answer 12

Metabolism and movement
Can sometimes be involved in gene expression

Question 13

Give an example of a receptor with intrinsic serine kinase

Answer 13

TGF-beta receptors (phosphorylate transcription factors)

Question 14

Give three examples of a receptor with intrinsic tyrosine kinase

Answer 14

Platelet Derived Growth Factor receptor

Insulin receptor

Epidermal Growth Factor receptor

Question 15

Give an example of a cytokine receptor linked to tyrosine kinase

Answer 15

Cytokine receptor -> Interleukin-3 receptor

Question 16

Compare receptors with intrinsic kinase activity to receptors linked to tyrosine kinases

Answer 16

Intrinsic: Kinase is part of the monomer activated after dimerisation

Linked: Receptor does not have kinase activity itself but interacts with a seperate kinase associated with the receptor

All other structural domains are the same

Question 17

What do ion channel receptors such as transient receptor potential (TRP) channels perceive?

Answer 17

Important for temperature perception, thermoperception, chilli

Question 18

Give an example of an ion channel receptor involved in cell signalling?

Answer 18

Transient receptor potential (TRP) channels

Question 19

Define ‘second messenger’

Answer 19

Intracellular metabolite or ion, which couples an extracellular stimulus to a physiological response

Question 20

Why do second messengers need to be small?

Answer 20

So that concentration of them can be increased very quickly, by synthesis, release from a store, and decreased very quickly, by breaking down or sequestering them