L11-Cell Signaling

Question 1

release of chemical compound where the same cell is the target cell

Answer 1

Auto-crine

Question 2

stages of cell signaling.

Answer 2

reception, transduction and response.

Question 3

reception definition?

Answer 3

the binding of the chemical compound/ligand to the receptor protein.

Question 4

Transduction?

Answer 4

the cascade of events initiated by the occupancy of the receptor protein where relay molecules are activated and cause activation of other relay molecules.

Question 5

types of relay molecules?

Answer 5

mostly enzymes and proteins but can be non proteins and ions as well.

Question 6

what molecules are secondary messengers?

Answer 6

relay molecules are secondary messages transmitting signal downstream.

Question 7

transduction cascade causes……….?

Answer 7

it causes the activation of proteins through the process of phosphorylation by kinases enzymes and deactivation of proteins through the process of dephosphorylation by phosphates enzyme.

Question 8

Response definition?

Answer 8

the last step where the signal causes cellular response like secretion, contraction cell division and differentiation.

Question 9

what are the 2 different types of receptors

Answer 9

A) cell surface receptors

B) intracellular receptors

Question 10

types of cell surface receptors?

Answer 10

A) ligand gated ion channels
B) G-coupled protein receptor
C) Enzyme linked receptor.

Question 11

explain the mechanism of ligand gated ion channels.

Answer 11

they are closed channels that have a receptor that binds with a specific ligand when the ligand binds with receptor it causes the channel to open and allow ions to pass through and when the ligand detaches the channel will close again. some channels are open and closes when ligand binds.

Question 12

where can you find ligand gated ion channel?

Answer 12

Neurones and muscle cells.

Question 13

Explain cystic fibrosis?

Answer 13

Gene mutation in chloride ion channels that are present on the surface of the epithelial cells. this defect doesn’t allow chloride ions out of the cell and reduce viscosity of mucus therefore, patients experience difficulty breathing.

Question 14

Explain the G protein coupled receptor.

Answer 14

upon binding of ligand the protein detaches form the receptor protein and the alpha subunit seperates from the rest of the protein and the GDP molecule is replaced by GTP and goes on to activate other relay molecules usually activates kinases that initiates phosphorylation.

Question 15

what are the subunits of the G-protein?

Answer 15

gamme beta and alpha subunits.

Question 16

what happens if the protein is active for too long?

Answer 16

initiates gene expression.

Question 17

state all the types of G proteins and their function

Answer 17

A) Gs –> stimulates adenylate cyclase (cyclic AMP pathway)
B) Gi –> inhibits adenylate cyclase ( cyclic AMP pathway)
C) Gq –> stimulates phospholipase (phosphinositide pathway)
D) G0 –> inhibits calcium ion channels.

Question 18

the cholera toxins effects on the body

Answer 18

the toxins released from the bacterium called Vibrio Cholerae causes ADP ribosylation of the Gs protein making the adenylate cyclase to become more active leading to an extended response cause secretion of water and chloride in the gut and constant contraction of intestine muscles causing severe and potentially fatal diarrhea

Question 19

the pertussis toxins effect on the body?

Answer 19

The toxins released also causes ADP ribosylation of Gi protein therefore the adenylate cyclase will not be inhibited and will be active longer causing an extended response. therefore, contractions of the airway occur causing difficulty breathing and severe coughing.

Question 20

explain the mechanism of the enzyme linked receptor

Answer 20

the ligand binds with receptor and the receptor is made of 2 subunits.

Question 21

what is special about enzyme linked receptors?

Answer 21

they have intrinsic enzyme activity or have enzyme closely attached to it.

Question 22

what are the 4 main types of enzymes linked receptor?

Answer 22

A) Receptor tyrosine kinases
B) Receptor Serine/threonine kinase
C) Tyrosine kinase associated receptors
D) receptor gunnel cyclase.

Question 23

receptor tyrosine kinase?

Answer 23

when the ligand binds with receptor, 2 receptors dimerizes activate their intrinsic tyrosine kinase inducing phosphorylation. its also the receptor for insulin hormone.

Question 24

receptor serine/threonine kinases?

Answer 24

upon ligand binding it activates their intrinsic kinase activity.

Question 25

tyrosine kinase associate receptor

Answer 25

upon binding of ligand it activates attached protein that phosphorylates tyrosine and initiates kinase

Question 26

receptor guanyl cyclase?

Answer 26

when ligand binds with receptor guanyl cyclase is activated and cGMP is produced as a secondary messenger

Question 27

what is RAS?

Answer 27

they are small proteins that are down stream from the receptor tyrosine kinase that can easily turn oncogenic, it becomes constitutively active causing uncontrollable division and cancerous transformation.