Chapter 13

Question 1

Identify the basic components of all signal-transduction pathways

Answer 1

Release of primary messenger
Reception of primary messenger
Relay of information by second messenger
Activation of effectors that directly alter physiological response
Termination of signal

Question 2

Primary messenger

Answer 2

Signal molecule; message received by the cell

Question 3

Secondary messenger

Answer 3

Intracellular chemical that relays message from ligand receptor complex

Question 4

Heterotrimeric g-protein

Answer 4

Activated by 7TM receptor

Question 5

Gαs

Answer 5

Activates adenylate cyclase

Question 6

Protein kinase A

Answer 6

Stimulated by cAMP

Question 7

Kinase

Answer 7

Enzymes that phosphorylates a substrate at expense of ATP

Phosphoralation (turns enzymes on and off by addition of phosphate)

Question 8

cAMP phosphodiesterase

Answer 8

Results in the activation of kinase A

Question 9

GTPase activity

Answer 9

Results in the reassociation of gα and gβψ

Question 10

Cholera

Answer 10

Due to persistant stimulation of Gαs

Question 11

Pertussis

Answer 11

Results from gαi inhibition

Question 12

Phospholipase C

Answer 12

Generates two second messengers

Question 13

Gαq

Answer 13

Activates phospholipase c

Question 14

Inisital triphosphate

Answer 14

Activates ca2+ channel

Question 15

Protein kinase c

Answer 15

Activated by diacylglycerol

Question 16

what are the three major classes of protein receptors?

Answer 16

7TM, receptors that dimerize and recruit, receptors that dimerize tyrosine kinases

Question 17

what are some of the structural features common to all membrane-bound receptors?

Answer 17

must have a site on the extracellular side of membrane where signal molecule can bind and have intracellular domain
binding of signal to receptor must induce structural changes intracellular

Question 18

why is GTPase activity of G proteins crucial to proper function of a cell?

Answer 18

GTPase terminates the signal…without activity after a pathway has been activated, it remains activated and unresponsive to changes in inital signal

Question 19

explain how small number of hormones binding to the extracellular surface of a cell can have a large biochemical effect inside of the cell

Answer 19

the initial signal (binding of the hormone by a receptor is amplified by channels and enzymes