cell signals and responses

Question 1

cell commicaiton methods

Answer 1

secretion
contact signalling via membrane bound molecules
contact signalling through gap junctions

Question 2

contact signalling via gap junctons

Answer 2

small ions rapidly transferred between cells

Question 3

chemical signalling secreted examples

Answer 3

endocrine
paracrine
autocrine
synaptic

Question 4

endocrine

Answer 4

hormone produced and enter blood stream

carried to target cell

Question 5

paracrine

Answer 5

local chemical mediator released

acts on cells in immediate evironment

Question 6

autocrine

Answer 6

on itself

Question 7

synaptic

Answer 7

neutrotransmittors released at synapses

diffuse to post synaptic cel

Question 8

signal flow chart

Answer 8

signal
reception
transducer and transferred
responce

Question 9

signals to cells

Answer 9

1) Growth factors
2) hormones
3) extracellular matrix (receptors can interact with the ECM)
4) chemicals
5) proteins
6) sugars
7) synaptic

Question 10

cell responses

Answer 10

1) Growth (Cell division)
2) differentiation
3) metabolism
4) contract/relax
- eg muscle cells
5) apoptosis
6) gene transcription
7) secretion
8) migration
9) membrane charge
- eg excitable cell

Question 11

what can a signal focus on

Answer 11

cell surface receptor

internal cell receptor

Question 12

what happens on binding to cell surface receptor

Answer 12

translate extraceullar to intracellular signal

Question 13

what can pass through the cell membrane

Answer 13

hydrophobic signal for intracellular receptors

transported to the nucleus

Question 14

types of membrane receptors

Answer 14

G protein coupled (heptahelical)
enzyme linked (receptor tyrosine kinases
ion channels

Question 15

characterisitcs of signal transduction

Answer 15

• specificity and high affinity
• amplification
• desensitisation when signal is present (may desensitise when fall below a threshold)
• integration of multiple signals to produce a unified responce

Question 16

how many times does a G coupled receptor go through the membrane

Answer 16

7 times

Question 17

what do G coupled protein receptors respond to

Answer 17

light
taste
smell
hormones

Question 18

G protein coupled receptor

Answer 18

integral transmembrane protein (outside binds to signal, inside interacts with signalling molecules)
Initiates signalling through secondary messengers e.g. CAMP via G protines

Question 19

G protein coupled receptor steps

Answer 19

1) Hormone binds to the G protein coupled receptor
2) Pink G protein is associated with the receptor, when inactive it is bound to GDP
3) When the hormone has bound, GDP is exchanged for GTP
4) This alters the structure of the G protein which is associated with the receptor
5) affinity is lost between the different subunits
6) The alpha unit with GTP is lost and can interact with other parts of the cell

Question 20

what happens if the alpha subunit is bound to GDP (G coupled protein receptor)

Answer 20

G protein will reform

inactive state of complex returns

Question 21

what type of receptor is Beta adrenergic receptor

Answer 21

G protein coupled receptor

Question 22

what does Beta adrenergic receptor bind to

Answer 22

adrenaline

noradrealine

Question 23

What is the beta adrenergic receptor targeted fro

Answer 23

beta blokers
B2 antagonists
(prevents signal by competing reducing blood pressure)

Question 24

What can be added to 3 different amino acids

Answer 24

phosphate

Question 25

phosphoryaltion and enzyme

Answer 25

kinase catalyses reaction of phosphate sticking to another moelcile

Question 26

what removes phosphate

Answer 26

phosphatases

Question 27

what are receptor tyrosine kinases

Answer 27

receptors on cell surface which are kinase
stick a phosphate on tyrosine
they are also enzymes themselves

Question 28

what do receptor tyrosine kinases do

Answer 28

stick phosphate onto themselves
molecule binds, 2 diff subunits of protein comes together
forms dimer on cell surface
activate themselves by phsophroyaltion

Question 29

reactions of cell surface receptors for growth factors cytokines and hormones

Answer 29

have intrinsic enzyme activity - unlike enzyme linked receptors
leads to change in charge once ligand binds
conformational change allows signalling molecules to bind and cascade

Question 30

enzyme linked receptos

Answer 30

2 subunits come together
change in conformation allows associated enzyme to join
then has activity
- receptor itself does not have activity until the enzyme joints

Question 31

ligand gated ion channel and types

Answer 31

receptor is an ion channel
- ligand binds and opens io channel 
- voltage or mechanical gates
Responce to ligan
- change in membrane potential
action potential

Question 32

example of ligand gated receptor

Answer 32

GABAa receptor
neurotransmittor
- opens Cl- sensitive pore
hyperpolarises neurone (inside cell is -)
firing of AP

Question 33

what can therapeutic targets do and effects of signalling

Answer 33

inhabit pathways by using targets to prevent signalling events occuring
- can be used in diseases, mutations in proteins ect, as these are dysregualted

Question 34

examples of therapeutic targeters

Answer 34

small molecule inhibitors

monoclonal antibodies