Cell Signaling

Question 1

What is cell signalling?

Answer 1

The process by which cells communicate with eash other and the environment, cell signaling changes cell behavior

Question 2

What discoveries have come from an improved understanding of cell signalling?

Answer 2

Improved understanding of communication with our environment (smell, touch, etc), therapies for cardiac failure, hypertension, tissue engineering

Question 3

What internal signals change cell behavior?

Answer 3

Hormones, Nutrients, Neurotransmitters, metabolities

Question 4

What external signals change cell behaviour?

Answer 4

Nutrients, toxins, sensory cues

Question 5

What is an autocrine signal?

Answer 5

when a cell signals itself

Question 6

What is a paracrine signal?

Answer 6

When a cell signals its neighbour

Question 7

What is an endocrine signal?

Answer 7

When a cell signals a cell far away (signal travels through circulatory signal)

Question 8

What are the basic steps of cell signalling?

Answer 8

1. Initiation
2. Propagation
3. Amplification
4. Cellular Response
5. Termination

Question 9

What happens during initiation? (Cell signalling)

Answer 9

A signal binds to a receptor on a cell

Question 10

What happens during propagation? (Cell signalling)

Answer 10

Signalling protein is triggered inside cell

Question 11

What happens during amplification? (Cell signalling)

Answer 11

signalling protein triggers other signalling proteins

Question 12

What happens during cellular response? (Cell signalling)

Answer 12

Effector proteins cause a change in behaviour

Question 13

What happens during termination? (Cell signalling)

Answer 13

Cell stops response

Question 14

Is the speed of cell response uniform?

Answer 14

No, it can be fast or slow

Question 15

What are the two main classes of cell signals?

Answer 15

Long Range (Endocrine), Short Range (Paracrine and Endocrine)

Question 16

What are characteristics of Long Range signals?

Answer 16

Signals are typically produced far from the target tissue, endocrine signals circulate through the animal

Question 17

What are characteristics of Short range signals?

Answer 17

Act on short distances, use paracrine / autocrine singaling

Question 18

What is Synaptic signalling?

Answer 18

Pre synaptic cell releases transmitters which trigger post - synaptic cell

Question 19

What is contact cell signaling?

Answer 19

Protein from inside of signalling cell hangs outside cell and triggers proteins on outside of target cell

Question 20

What is an example of an endocrine signal?

Answer 20

Adrenaline, released from the adrenal gland, travels through the blood and signals the whole body

Question 21

Do all cells respond to all signals?

Answer 21

No - a cell can only respond to a signal if the cell expresses a receptor for that signal

Question 22

Can there be multiple receptors for a single signal?

Answer 22

Yes, Acetylcholine can cause salivation, skeletal muscle contraction, and decreasing heart rate

Question 23

What are the two classes of signal receptors?

Answer 23

Cell surface, intracellular

Question 24

How do cell surface receptor work?

Answer 24

They interact with a receptor protein which initiates a intracellular signalling cascade which creates change in cell

Question 25

How to intracellular cell receptors work?

Answer 25

They diffuse through plasma membrane, interact with a receptor protein and directly change the function of a cell (ie. cortisol)

Question 26

How do cells make decisions when integrating multiple signals?

Answer 26

???

Question 27

What are the three types of cell - surface receptors?

Answer 27

Ion-channel coupled, g-protein coupled, enzyme linked

Question 28

How do pre - synaptic cells interact with post - synaptic cells in ion channel coupled receptors?

Answer 28

???

Question 29

Discuss the changes to membrane potential, opening voltage gated channels, propagating signal down the neuron and stimulating exocytosis of new neurotransmitters to the next neuron

Answer 29

???

Question 30

What are the 4 features of GPCRs?

Answer 30

1. Transverse the membrane as 7 alpha helices 2. 7000 Members in the family 3. Signals that bind to GPCRs include hormones, neurotransmitters, fatty acids, proteins, odourants, etc 4. Amenable to pharmacological manipulation

Question 31

What do the GPCR and G protein subunits sub-units (α, β, γ) look like at rest?

Answer 31

α subunit binds to GDP, α and γ are tethered to cell membrane

Question 32

What happens at initiation in GPCRs signal through G proteins?

Answer 32

signal / ligand binds to CPCR on outside of cell which causes α to associate with GDP, α dissociates from β and γ

Question 33

What happens at propagation in GPCRs signal through G proteins?

Answer 33

α and βγ subunits of G proteins associate with many | targets

Question 34

What happens at amplification in GPCRs signal through G proteins?

Answer 34

Activated G proteins associate with enzymes which trigger second messenger

Question 35

What are examples of second messengers in GCPR cell signalling?

Answer 35

cyclic AMP, inositol triphosphate, diacylglycerol, Ca2+, cyclic GMP

Question 36

Describe how cAMP is involved in signal amplification

Answer 36

adenylyl cyclase produces cAMP and phospholipase C,

Question 37

Identify two features of an enzyme-linked receptor

Answer 37

Often have only a single transmembrane pass, and alpha helix , Signals that activate enzyme-linked receptors include hormones and growth factors

Question 38

Describe the sequence of events that occurs | after a signal binds to an enzyme-linked receptor

Answer 38

1. Receptor tyrosine kinases dimerize upon ligand binding, Dimerization induces receptor tyrosine kinase activity 2. Activated receptor recruits many proteins 3. Receptor-associated proteins amplify the signal, Several enzyme-linked receptors activate GTPase Ras 4. Activation of Ras has diverse effects on cellular proteins and transcription to change cell behaviour 5. Protein tyrosine phosphatases terminate the signal

Question 39

Compare and contrast cell signaling mediated by GPCRs and enzyme-linked receptors

Answer 39

???

Question 40

Name two diseases linked with GPCRs

Answer 40

Hypertension, congestive | heart failure

Question 41

Name two diseases linked with enzyme-linked receptors

Answer 41

Congenital growth disorders § Craniosynostosis