Signal Transduction Introduction

Question 1

What do signals need to be functional

Answer 1

Need to bind to a receptor

Question 2

What do signals that can’t pass the membrane do

Answer 2

They transmit their signal by changing the receptors confirmation

Then Get amplified

Question 3

What is signal transduction

Answer 3

When info from extra cellular molecules gets translated to a internal cellular signal

Question 4

What are the two types of communications

Answer 4

Electrical

Chemical

Question 5

What is electrical communication

Answer 5

It involves a gap junction

Question 6

What is chemical communicatuon

Answer 6

Protiens such as hormones, neurotransmitters, growth factors

Act as a stimulus to a receptor on the plasma membrane to go from outside the cell to the inside

Question 7

What is the order to transduction in chemical communication

Answer 7

Stimuli

Receptors

Signalling pathway:

Transducers

Amplifiers

Messengers

Sensor and effectors

Cellular responses

Question 8

What is receptor based signalling

Answer 8

When the target cell to get the signal has a receptor that binds specific signals

The receptors are transmembrane and could also be cytosolic

Question 9

What does it mean I receptors are cytosilic

Answer 9

The signal (ligand) has to cross the membrane on its own

Question 10

What are the 4 mechanism of cell stimulus

Answer 10

Juxtacrine

Autocrine

paracrine

Endocrine

Question 11

What is juxtacrine

Answer 11

Both the receiving and donating cells are membrane bound (on their recpective cells) and also very close together

Question 12

What is autocrine/paracrine

Answer 12

The signalling and the target cell are the same cell or a neighbouring cell

Autocrine signals happen to stimulate their own receptor signal transduction

Question 13

What is endocrine signalling

What are they type of signals in this type of transduction

Answer 13

A singal is carried throughout the body first though the blood then sent to target cells throughout the body

Ex. Estrogen, testosterone, prolactin

Question 14

What are the 6 classes of receptors

Answer 14

G protien coupled receptor (GPCR)

Cell surface receptors

Receptor tyrosine kinases (RTK)

Steroid hormone receptors

Cytokine receptors

Ion channel receptors

Question 15

What are RTK

Answer 15

have phosphorylated things

Question 16

What are steroid hormone receptor

Answer 16

Receptors that are inside the cell

This is where the signal needs to travel across the plasma membrane (ex. Estrogen/testosterone)

Question 17

Whit is Cytokine receptor

Answer 17

Immune signalling molecules bind

Dimer receptor

Question 18

What are the 5 types of extracellular messengers (signals)

Answer 18

Amino acids and their derivatives (ex epinephrine)

Gases, NO and CO

Steroids derived from cholesterol (hydrophobic, can cross the membrane, ex. Testosterone and estrogen)

Eicosanoids that are derived from arachadonic acid

Protien ligands (most of the messengers)

Question 19

What are the basic elements of cell signalling systems

Answer 19

Receptors on or in the target cell that recive the extracellular message

Ligands the bind to the receptor

A second messanger system the help in giving a response to the ligands or Cytoplasmic protien recruitments

Question 20

What is a second messenger system

Answer 20

An enzyme called the effector makes the second messanger

The second messanger amplifies the signal

Question 21

How does a second messenger system work

Answer 21

When there is no singal the second messenger is not abundant in the cell

When signal is in receptors, effectors make more and more second messengers which amplify the signal

Question 22

Slide 13 blank

Answer 22

Okay

Question 23

What are signalling pathways in signal transduction via a phosphorylation cascade

Answer 23

A series of protiens where each protien in the pathway changes the conformation of the next protien

The change in conformation (to be active) happens after its phosphorylated by a kinase
Can be dephisphotlsted by phosphatase

Then the target protein down the pathway eventually also gets the message and alters the activity of the cell

Question 24

Why does signal transduction happen

Answer 24

When there is no second messenger

Question 25

What is reversible phosphorylation

What things can get phosphorylated

Answer 25

When protien kinases transfer a phosphoryl group from atp to a substrate protein

But the protien phosphatase removes it

Ser, thr, tyr, his, arg

Question 26

Start of ones I didn’t do

Answer 26

Slide 16

Question 27

How is signal transduction controlled

Answer 27

expression of a ligand specific receptor (only takes in specific signals)

Timing of docking protien activation

presence/absense of docking sites

Inhibitory protien that prevent certain signals

Question 28

Slide 17

Answer 28

Okay

Question 29

What is the prolactin JAK STAT pathway

Answer 29

Is used a phosphorylation cascade

Prolactin binds to the cytokine prolactin receptor

When prolactin binds, the two receptor chains close in and dimerize, do a conformational change

After the conformational change, a tyrosine kinase next to the receptor jak2 gets activated

A phosphorylation cascade of STAT molecular happen where the STAT molecules dimerize at sh2 domains

The dimer stat molecules act as “signal transducer and transcription” factors when active

Question 30

What turns off prolactin JAT STAT pathway

Answer 30

Phosphatase

Question 31

Alide 16 to check liaba

Answer 31

Okay

Question 32

What is a second messenger

Answer 32

A non protien molecule that amplifies the signal inside the cell