Cell Signaling

Question 1

The type of intrercellular communication where local mediators act on neighboring cells

Answer 1

Paracrine

Question 2

The type of intrercellular communication where cells are in membrane contact

Answer 2

Contact dependent

Question 3

The type of intrercellular communication where hormones are secreted into the bloodstream to a distant location

Answer 3

Endocrine

Question 4

The type of intrercellular communication where electrical signals are transmitted along axons

Answer 4

Synaptic

Question 5

Signaling molecules are typically

Answer 5

Hydrophillic and therefore unable to cross the cell membrane

Question 6

The three factors that affect the response to a signal are

Answer 6

• The receptors
• Intracellular signaling proteins
• Activated genes

Question 7

The Cell-Surface Receptor ion-channeled-coupled acts by

Answer 7

Rapid synaptic signalling, where neurotransmitters open or close to change the membrane permeability to ions

Question 8

The Cell-Surface Receptor G-Protein-coupled acts by

Answer 8

Indirectly regulates the activity of the target protein or ion channel and is mediated by a trimeric GTP binding protein.

Question 9

The Cell-Surface Receptor enzyme-coupled acts by

Answer 9

They are enzymes or associate directly with them

Question 10

Secondary messengers operate by

Answer 10

They are activated by the receptor activation, generate in large amounts, and find and alter behavior of receptor proteins

Question 11

Positive feedback is when

Answer 11

The activated enzyme complex increases the reaction rate of activating itself

Question 12

Negative feedback is when

Answer 12

The activated enzyme complex increases the reaction rate of dissociating itself

Question 13

Since GCPR’s stay active as long as the signal is bound, they typically

Answer 13

Activate multiple G-Proteins

Question 14

cAMP activates PKA after G-Proteins activate which enzyme

Answer 14

Adenylyl cyclase

Question 15

(T/F) All secondary messengers are water soluble and diffuse freely through the cell

Answer 15

F; While Ca2+ and cAMP can, not all of them can

Question 16

(T/F) In the regulation of molecular switches, GEFs and protein kinase always turn proteins on and GAPs protein phophatases always turn them off

Answer 16

F; The protein enzymes can do either, depending on the protein

Question 17

(T/F) Most intracellular signaling pathways provide numerous opportunities to amplify the responses to extracellular signals

Answer 17

T; Sort of the idea that an activated receptor protein can then activate a whole bunch of enzymes.

Question 18

(T/F) Binding of extracellular ligands to receptor tyrosine kinases activates the intracellular catalytic domains by propagating a conformational change across the lipid bilayer through a single transmembrane alpha helix

Answer 18

F; Activation is done via self phosphorylation

Question 19

Signaling via phosphorylation is deactivated by

Answer 19

Being dephosphorylated by phosphotase

Question 20

Signaling via GProteins is deactivated by

Answer 20

Inherent ability to hydrolyze and turn itself off over time

Question 21

(T/F) cAMP is a secondary messenger

Answer 21

True

Question 22

The RTK pathway is turned off by

Answer 22

Tyrosine phosphatase dephosphorylates the RTK

Question 23

The downstream activity of Gs is

Answer 23

Activates adenylyl cyclase, increases cAMP

Question 24

The downstream activity of Gq is

Answer 24

Activates phospholipase C, increasese IP3 and diacylglycerol and then eventually increases Ca2+ and PKC

Question 25

The downstream activity of Golf is

Answer 25

Increase adenylyl cyclase, increases cAMP

Question 26

The downstream activity of Gi is

Answer 26

Inhibit adenylyl cyclase activity, decreases cAMP