Cell Communication

Question 1

what must a cell do in order to receive a signal?

Answer 1

communicate and amplify them

Question 2

what is the signal transduction pathway?

Answer 2

a cascade of reactions caused by a binding of the signal messenger

Question 3

what does the singal transduction do?

Answer 3

produces the physiologval effect of the signal

Question 4

what is local communication?

Answer 4

through direct contact or by secreting local acting GFs and cytokines

Question 5

what are cytokines?

Answer 5

a large family of small secreted proteins released by cells which effect the interactions between cells

Question 6

what is long distance communication?

Answer 6

uses hormones to communicate

Question 7

where are hormones made?

Answer 7

endorcrine glands

Question 8

what is a gland?

Answer 8

a group of cells in the body that synthesises substances such as hormones for release into the bloodstream

Question 9

what is cortisol?

Answer 9

glucocorticoid that is produced in the cortex of the adrenal gland that alters carbohydrate metabolism

Question 10

what is aldosterone?

Answer 10

mineralocorticoid produced in the cortex of the adrenal gland which regulates salt and water balance

Question 11

what is thyroxine?

Answer 11

produced by the thyroid gland and stimulates metabolism and heat generation

Question 12

what is the difference between the GFs and cytokines?

Answer 12

GFs are produced constituitively yet cytokines are carefully regulated

Question 13

in what ways do hormones act?

Answer 13

long range and endocrine fashion

Question 14

in what ways do cytokines act?

Answer 14

over a short distance and in autocrine or paracrine fashion

Question 15

what is neural signalling?

Answer 15

nerve cells or neurones elicit responses by the release of a neurotransmitter at synapses

Question 16

what is contact dependance?

Answer 16

singal molecules in the plasma membranes of the signal cellinteract with membrane receptors on the target cell

Question 17

what alters the cells sensitivity to signalling molecules?

Answer 17

the receptor density in the membrane

Question 18

how does the ligand messenger model work?

Answer 18

ligand is the first messenger and the ions produced as a result are the second messengers

Question 19

what 3 receptors are often a cause of disease?

Answer 19

ligand gated ion channels, G-protein coupled receptors and tyrosine kinases

Question 20

what are ligand gated ion channels?

Answer 20

transmembrane proteins open or close in response to ligand

Question 21

why are ligand gated ion channels important?

Answer 21

for neurotransmitters to carry a nervous impulse

Question 22

what do GPCR’s look like?

Answer 22

a polypeptide chain with 7 transmembrane alpha helices

Question 23

what is the structure of GPCR’s?

Answer 23

outer temrinal binds to ligand and inner terminal binds to G protein

Question 24

what is the heterotrimeric G protein?

Answer 24

made up of alpha, beta and gamma subunits that are activated by GPCR’s

Question 25

what is an unstimulated G protein?

Answer 25

interacts with GDP

Question 26

what happens when ligand binds to GPCR?

Answer 26

G alpha dissociates from dimer and GDP exchanged from GTP

Question 27

what are receptor tyrosine kinases?

Answer 27

high affinity cell receptors for GFs such as cytokines and hormones

Question 28

what is a kinase?

Answer 28

enzymes that add phosphate groups

Question 29

why are kinases important?

Answer 29

have a key role in regulating cell growth and survival

Question 30

what happens when ligand binds to the receptor in tyrosine kinases?

Answer 30

receptors join and dimerize

Question 31

what does dimerization of the terminals do?

Answer 31

causes the tyrosine kinase domains to become activated

Question 32

what happens when the domains are activated?

Answer 32

the opposite tyrosine molecule is phosphorylated

Question 33

what does the phosphorylated tyrosine now do?

Answer 33

activates the intracellular signal proteins

Question 34

how does the signal then occur in tyrosine kinases?

Answer 34

intracellular signal proteins trigger an intracellular signalling pathway