Signal transduction W4

Question 1

three common elements of signal transduction pathways

Answer 1

receptor
intermediate
target

Question 2

signal transduction is the process by which a cell…..

Answer 2

converts one kind of signal into another sequence of rapid biochemical reactions

Question 3

components of signalling pathways (5)

Answer 3

first messengers/signals/ligand

receptor

second messengers/intermediates

target

response

Question 4

what is a lignad

Answer 4

something that binds to another molecule

Question 5

what are first messengers/ signal / lignd

Answer 5

extracellular factors eg hormones neurotransmitters

Question 6

what do receptors do

Answer 6

receive initial signal from messenger/signal/ligand

Question 7

what does the second messenger/intermediate do?

Answer 7

amplifies the signal from receptor to target

Question 8

what does the target do

Answer 8

interacts with intermediate to initiate response

Question 9

a cell receives a signal what are the four common outcomes of this

Answer 9

can lead to activation or inhibition of

• protein synthesis/gene expression
• enzyme activity
• membrane channels
• cellular processes (eg cell division, metabolism, transport)

Question 10

where can receptors be found

Answer 10

they can be membrane bound or internal

Question 11

how does the ligand enter the cell

Answer 11

via diffusion

Question 12

explain how signalling is specific

Answer 12

only cells with specific receptor will respond to a corresponding signal

Question 13

describe the differnece between outocrine and paracrine signalling

Answer 13

autocrine signaling means that the initial signal/messenger/lignad is produced by the same cell that receives it

paracrine signalling occurs when the initial messenger/signal/ligand is received by a different cell from which it was produced (you have a signalling cell and a target cell)

Question 14

explain long distance signalling (endocrine)

Answer 14

occurs when for eg hormones travels through body via bloodstream to target celss

Question 15

what is the primary requirement for all signalling

Answer 15

that it is easily reversible

Question 16

Three major classes of extracellular receptors

Answer 16

ligand gated ion channels

enzyme-coupled receptors

G-protein-coupled receptors

Question 17

cascading chain of reactions - how is kinase and phosphatase involved

Answer 17

kinase - activates proteins by adding a Pi

phosphotase inactivated proteins by removing a Pi

Question 18

explain phosphorylation cascade

Answer 18

phosphate attaches to protein = activates

releases phosphate= deactivates, phosphate travels to next protein and chain continues

Question 19

G- protein coupled receptors (GPCRs) have …..transmembrane domains

Answer 19

7

Question 20

what are G proteins associated with

Answer 20

GPCRs

Question 21

what is the structure of a G protein

Answer 21

it is heterotrimeric with three subunits (alpha beta gamma)

Question 22

what does the alpha subunit of a g protein do

Answer 22

exchanges GDP for GTP

Question 23

what does the alpha subunit containing GTP do

Answer 23

it goes to adenylate cyclase (AC) which generates a second messenger from ATP—cylcic AMP (cAMP)

Question 24

dysregulation in signal transduction contributes to diseases such as …(4)

Answer 24

cancer, endocrine, autoimmune and neurological disorders