chapter 9

Question 1

paracrine signalling is characterized by ligands that are

Answer 1

secreted by neighboring cells

Question 2

endocrine signalling- define

Answer 2

horomones enter circulation and carried to target cells distance away

Question 3

direct contact refers to :

Answer 3

molecules on plasma membrane of one cell contact receptor molecules on an adjacent cell

Question 4

define synaptic signalling

Answer 4

neurotransmitters released by neurons into synapse

Question 5

signal transduction pathways :

a) are nessecary for signals to cross the membrane
b) include intracellular events stimulated by EC signal
c) ec events stim’d by IC signal
d) only found where signal can cross membrane

Answer 5

b) include IC events stimd by EC signal

Question 6

the function of a ________ is to add phosphates to proteins and the function of a ________ is to remove phosphates from proteins

Answer 6

protein kinase, protein phosphotase

Question 7

which of the following is NOT a membrane receptor
channel linked
enzymatic
gpcr
steroid

Answer 7

steroid horomone receptors are intracellular bc nonpolar hydrophobic steroid horomones cross membrane

Question 8

how does ic receptor differ from membrane receptor

Answer 8

intracellular receptor binds to DNA

Question 9

signaling through receptor protein kinases often?

Answer 9

leads to activation of a cascade of kinase enzymes

Question 10

what is the function of Ras during tyrosine kinase cell signalling

Answer 10

links receptor protein to MAP kinase pathway

Question 11

what is the immediate effect of a ligand binding to a GPCR

Answer 11

G protein trimer releases gdp and binds to gtp

Question 12

the action of steroid horomones is often longer lived because

Answer 12

they turn on gene expression to produce proteins that persist in the cell

Question 13

calcium ions can act as second messengers because

Answer 13

it is normally at a low level in the cytoplasm,

Question 14

different receptors can have the same effect on a cell because

Answer 14

signal transduction pathways intersect- same pathway can be stimulated by different receptors

Question 15

in comparing small g proteins such as ras and GPCR proteins we can say that:

Answer 15

both proteins have intrinsic gtp ase activity that stops signalling
both proteins are bound to an active GTP

Question 16

the same signal can have different effects in different cells because

Answer 16

there are different receptor subtypes that initiate different signal trans pathways
may be different co activators
may be different target proteins in different cells signal pathways
all are true

Question 17

receptors of steroid horomones and peptide horomones are different because

Answer 17

peptides are hydrophillic and steroids are hydrophobic

Question 18

ligands_____________

Answer 18

a wide variety of moldecules that bind to internal(hydrophobic) or external(hydrophillic) cell receptors

Question 19

true or false a signalling network is always linear

Answer 19

false

Question 20

steroid horomone estrogen binds to which cell surface receptor?

Answer 20

none- hydrophobic steroid horomones bind internally

Question 21

cell commmunication begins with a ____ that binds to a ____ initiating a ____ that leads to a ____

Answer 21

ligand, receptor. signal transduction pathway, cell response

Question 22

Calcium as a second messenger can

Answer 22

bind to calmodulin to activate cell response proteins

Question 23

phosphorlyation cascades can be organized by

Answer 23

scaffold proteins which sequester enzymes from other signalling pathways

Question 24

upon GPCR activation phospholipase C can cleave inositol phospholipids to create

Answer 24

IP3 and DAG which have different signalling consequences

Question 25

when enough calcium is released into cyto plasm , in can saturate calcium binding sites of calmodulin which causes calmod to change shape and allows it to bind to new proteins (T/F)

Answer 25

truuuuuuuuu

Question 26

epinepherine and glucagon are different ligands which can initiate the same series of events in a single celll, and epinepherine can initiate different responses in different cell types t/f

Answer 26

true

Question 27

if a ligand binds with a __ it will __ and if the ____ is gtp bound it could initiate a ____

Answer 27

receptor tyrosine kinase, dimerize and autophosphorylate, activator, phosphorlyation cascade