Intracellular Signalling 3

Question 1

What is signal transduction process?

Answer 1

It is converting a signal into a response (or inhibiting, modifying or amplifying)

Question 2

Two principles of cell signalling/typical cellular communication

Answer 2

-Signalling cell produces a signal molecule
-Signal molecule detected by receptor protein on target cell (kinda like insulin and liver cell receptors)

Question 3

What are the three important classes of signalling molecules?

Answer 3

1.Hormones-SM of endocrine system

2.Neurotransmitters-SM of the nervous system (includes neuropeptides and neuromodulators)

3.Cytokines-signalling molecules of the immune system

Question 4

Signalling molecules can be pkg to several chemical classes such as?

Answer 4

Lipids/phospholipids
AAs
Monoamines
Proteins glycoproteins
Gases

Question 5

Some structural attributes of SM that bind to surface receptors?

Answer 5

They are usually large and hydrophilic (eg. Acetyl choline, insulin)

Question 6

Structural attributes of signalling molecules that enter the cell?

Answer 6

Usually small and hydrophobic (eg.glucocorticoids and cortisol)

Question 7

Based on distance between signalling cells and responders, what are the four main ways to send signals between cells?

Answer 7

1.Endocrine
2.Paracrine and autocrine
3.neuronal/synaptic
4.Contact-Dependent

Question 8

How do endocrine hormones get distributed?

Answer 8

Endocrine cell produces hormone and it enters the bloodstream travelling to receptor of target cell (INSULIN)

Question 9

How are paracrine and autocrine signals distributed?

Answer 9

Signals released by signal cell into extra cellular fluid for local receptors

Question 10

How are synaptic(neuronal) signals distributed?

Answer 10

Neuronal signals are transmitted along axons to remote target cell synaptic junctions where neurotransmitters released

Question 11

How does Contact dependant signalling work?

Answer 11

Cell surface bound SM binds to receptor protein on target cell

Question 12

Each cells responds to a limited set of signals depending on state

How many SMs is a single cell in a multicellular organism exposed to?

Answer 12

A single cell is exposed to 100s of different SMs at any one time

And must select which to respond to (depends on presence of receptor protein)

Question 13

Each receptor is usually activated by one type of signal…

Answer 13

-without the appropriate receptor - no response

-Limits the signals the cell will respond to

Question 14

What can the same signal do?

Answer 14

It can elicit a different response depending on cell type and activation state (eg acetylcholine)

Question 15

Every molecule has a set of receptor proteins which means…

Answer 15

Different sets of SMs working together can elicit different types of responses

Question 16

How does CSM receptors work?

Answer 16

They pass on signal to intracellular SMs altering the activity of an effector protein leading to altering in the cell

Question 17

What can intracellular signalling proteins do?

Answer 17

Intracellular signalling proteins can relay,amplify,integrate, and distribute incoming signal

Question 18

What do intracellular signalling proteins act as?

And what’s re the two classes?

Answer 18

Act as molecular switches to ensure proteins can be reset

1.Addition/removal of phosphate group - phosphorylation status

2.Whether bound to GTP or GDP - GTP binding proteins

Question 19

Two classes of molecular switches in intracellular signalling proteins

Answer 19

Amino acid phosphorylation

GTP binding proteins