Lec 2.10 Cell communication

Question 1

What is Signal Transduction?

Answer 1

Cell to Cell communication. Extracellular signaling molecules bind to specific receptors in target cells to initiate a chain of events.

Question 2

What 2 major types of responses do external signals induce?

Answer 2

Fast and slow response

Question 3

What happens in the fast response?

Answer 3

Change in activity or function of enzymes or proteins in cell

Question 4

What happens in the slow response?

Answer 4

change in amounts of proteins by change in expression of genes.

Question 5

What happens if you interrupt the signal transduction pathway for Leptin?

Answer 5

Over eating. Dont know youre full.

Question 6

What are the 5 types of signaling?

Answer 6

Endocrine, Paracrine, synpatic, Autocrine, direct cell

Question 7

What is endocrine signaling?

Answer 7

Long distance signaling. Long lasting.

Question 8

What is paracrine signaling?

Answer 8

Acts locally at cells nearby. Short lived.

Question 9

What is synaptic signaling?

Answer 9

Acts locally at cells nearby. Short lived.

Question 10

What is an ex of synaptic signaling?

Answer 10

Neurotransmitters

Question 11

What autocrine signaling?

Answer 11

Cells response to signals that they themselves released or cells that are the same type as them have released.

Question 12

What is an ex of autocrine signaling?

Answer 12

Growth factors in cancer cells

Question 13

What is direct cell signaling?

Answer 13

Another way of signaling.

Question 14

What are two ex of direct cell signaling?

Answer 14

Immune cells. Presenting cells to T cells.

Question 15

What are the two types of receptors?

Answer 15

Cells surface receptors, Intracellular receptors

Question 16

Why cant most ligands or hormones get into a cell?

Answer 16

They are hydrophilic or large

Question 17

What are the 3 parts of the G-protein-coupled receptors?

Answer 17

1. Extracellular domain. 2. Transmembrane domain. 3. Cytoplasmic domain.

Question 18

What does the extraceullular domain do in the G-protein-coupled receptors?

Answer 18

binds to ligand

Question 19

What does the transmembrane domain do in the G-protein-coupled receptors?

Answer 19

anchors receptor

Question 20

What does the cytoplasmic domain do in the G-protein-coupled receptors?

Answer 20

associates with G-protein

Question 21

What are the G-proteins composed up of?

Answer 21

3 subunits. Alpha, Beta, gamma.

Question 22

What do heterotrimeric G proteins do?

Answer 22

Regulate target enzymes

Question 23

What are the 6 steps to signaling by Trimeric G-proteins?

Answer 23

1. Inactive. 2. Activation of receptor by ligand binding. 3.Activated receptor binds to G-protein (acts as GEF). 4. G alpha releases GDP and binds GTP, and dissociates from G beta gamma. 5. G alpha binds and activated adenylyl cyclase. 6. G alpha hydrolyses GTP to GDP, dissociates from adenylyl cyclase and binds G beta gamma (inactive).

Question 24

What is Adenylyl cyclase? What does it generate?

Answer 24

Effector protein. Generates cAMP.

Question 25

What does cAMP do?

Answer 25

Goes on to interact with its target proteins to cause a biological response.

Question 26

What disease deals with G proteins?

Answer 26

Cholera.

Question 27

What does Cholera do to G proteins?

Answer 27

Modifies G protein by keeping the G alpha in the GTP active form forever. Thus making pathway always active. Causing diarrhea.

Question 28

What does cAMP activate?

Answer 28

PKA

Question 29

What results in an Active PKA?

Answer 29

Binding of 2 cAMP molecules.

Question 30

What can PKA do?

Answer 30

Regulate proteins by adding phosphate group.

Question 31

What does adding a phosphate group to a protein do (PKA)?

Answer 31

Adds two negative charges that change conformation of protein

Question 32

What are 4 things that PKA can also do?

Answer 32

1. Phosphate group can form part of structure that other proteins recognize. 2. Activation/inactivation of enzymatic target proteins. 3 Alteration of intracellular localization of target proteins. 4. Change abundance of target proteins

Question 33

What can induce activation of PKA?

Answer 33

Epinephrine

Question 34

Name and describe the 4 types of cell signaling.

Answer 34

1. endocrine signaling: Long distance signaling. Long lasting. 2. Paracrine signaling: Acts locally at cells nearby. Short lived. 3. Synaptic signaling: Acts locally at cells nearby. Short lived. 4. Direct cell signaling: Immune cells. Presenting cells to T cells.

Question 35

Describe the steps from binding of a ligand to a G protein coupled receptor to production of a 2nd messenger to induce an effector response.

Answer 35

1. Inactive. 2. Activation of receptor by ligand binding. 3.Activated receptor binds to G-protein (acts as GEF). 4. G alpha releases GDP and binds GTP, and dissociates from G beta gamma. 5. G alpha binds and activated adenylyl cyclase. 6. G alpha hydrolyses GTP to GDP, dissociates from adenylyl cyclase and binds G beta gamma (inactive).

Question 36

How do cyclic AMP and PKA work to bring about a response?

Answer 36

0. Regulate proteins by adding phosphate group. 1. Phosphate group can form part of structure that other proteins recognize. 2. Activation/inactivation of enzymatic target proteins. 3 Alteration of intracellular localization of target proteins. 4. Change abundance of target proteins

Question 37

Name and describe 3 ways to stop a signal in a signal transduction pathway

Answer 37

1. Receptor sequestration: endosome invagination of memebrane. 2. Receptor destruction: endosomes + lysosomes. 3. Removal of signaling molecule: phospohodiesterases will remove cAMP.