9. Cell Signalling Overview

Question 1

name 3 hydrophobic signals

Answer 1

steroids
retinoids
thyroxine

Question 2

what is the most common method of signalling

Answer 2

extracellular mediator signals

Question 3

what is autocrine signalling

Answer 3

signalling and reception by the same cell

Question 4

when does autocrine signalling frequently occur

Answer 4

cell division

- growth regulation

Question 5

what is paracrine signalling?

Answer 5

signalling between nearby cells

Question 6

what is endocrine signalling

Answer 6

signalling via distant cells via hormones

Question 7

describe the effects of paracrine signalling

Answer 7

local and short lived

Question 8

when may paracrine signalling be used

Answer 8

in embryonic development

Question 9

what type of signalling is synaptic signalling

Answer 9

paracrine signalling - between two nerve cells or at a neuromuscular junction

Question 10

what does endo mean?

Answer 10

within

Question 11

what type of glands are involved in endocrine signalling

Answer 11

ductless glands that secrete hormones

Question 12

give an example of an endocrine gland

Answer 12

pituitary
adrenal
thyroid

Question 13

name 3 types of extracellular mediators

Answer 13

hormones
growth factors
steroid hormone

Question 14

name 3 types of receptors

Answer 14

G-protein coupled receptors
receptor tyrosine kinases
ion channel receptors

Question 15

how many TMS Alpha helices in GPCRs

Answer 15

7

Question 16

how many extracellular and intracellular domains in GPCRs

Answer 16

4 extracellular & 4 cytosolic

Question 17

name 3 processes GPCRs are involved in

Answer 17

metabolism
movement
modulating gene expression

Question 18

GPCRs work with the help of a G-protein- what can this bind

what does this act as

Answer 18

can bind guanine nucleotides:
GTP & GDP

acts as a molecular switch

Question 19

what happens when GDP is bound?

Answer 19

G-protein is inactive

SWITCHED OFF

Question 20

What happens when GTP is bound

Answer 20

G-protein is activated

SWITCHED ON

Question 21

what side of the membrane is the G-protein attached to loosely

Answer 21

cytoplasmic side of the cell membrane

Question 22

how do receptor tyrosine kinases (RTKs) differ to GPCRs

Answer 22

RTKs have intrinsic enzyme activity

Question 23

what happens when a ligand binds to a RTK

Answer 23

previously exist as monomers

when activated- dimerisation occurs = activating a kinase

Question 24

define second messengers

Answer 24

intracellular metabolite or ion which couples an extracellular stimulus to a physiological response

Question 25

name 4 criteria a molecule must fulfil to be classed a second messenger:

Answer 25

• be small
• can be rapidly produced & hydrolysed
• controlled by extracellular stimuli
• able to be amplified

Question 26

give 2 examples of cyclic nucleotide second messengers

Answer 26

cAMP

cGMP

Question 27

give 2 examples of lipid-derived second messengers

Answer 27

1,2 diacylglycerol

Inositol 1,4,5 triphosphate

Question 28

what does cAMP activate

Answer 28

protein kinase A

Question 29

what does cGMP activate

Answer 29

protein kinase G

Question 30

what does IP3 activate

Answer 30

calcium dependent protein kinases

Question 31

what is cAMP used for

Answer 31

increase lipid hydrolysis

decrease glycogen synthesis

Question 32

what is cGMP used for

Answer 32

opens cation channels in rod cells

Question 33

what does IP3 do

Answer 33

opens calcium channels in the ER

Question 34

what does DAG activate

Answer 34

protein kinase C

Question 35

is phosphorylation reversible or irreversible?

Answer 35

reversible

Question 36

what molecule is involved in dephosphorylation

Answer 36

protein phosphatase