Week 5- cell signaling Drews

Question 1

universal features of chemical messaging

Answer 1

Secreted by specific cells
Diffused or transported to target cells
Bind to receptor
Elicits response
Signal is terminated

Question 2

prostaglandins

Answer 2

from arachidonic acid

for inhibiting platelet aggregation

Question 3

thromboxanes

Answer 3

arachidonic acid ⇒ prostaglandins ⇒ thromboxanes which stimulates platelet aggregation

Question 4

4 types of cell signaling

Answer 4

1) endocrine- releases message ⇒ goes through circulation to get to target site (x: pancreas releasing insulin)
2) paracrine- compound releases chemical signal which affects something right next to it
3) autocrine- compound releases signal that binds to a target site which is on the same compound that released it
4) juxtacrine –signal is never really released: compound must be in contact with the target cell

Question 5

Trace the biosynthesis of NO (nitric oxide).

Answer 5

ACh activates nitric oxide synthase → nitric oxide is produced and released into blood → NO binds to guanylyl cyclase in smooth muscle to produce cGMP from GTP → increase in cGMP causes smooth muscle relaxation and vasodilation

Question 6

Identify the three main classes of cell-surface receptors

Answer 6

Ion channels
Kinase receptors
GPCR (heptahelical receptor)

Question 7

nitroglycerin

Answer 7

can be broken down into NO

given to patients with chest pain to vasodilator ==> increase blood flow to hypoxic areas (low O2)

Question 8

Types of Intracellular receptors

Answer 8

1) cytoplasmic receptors
2) nuclear receptors
3) plasma membrane receptors

Question 9

3 types of plasma membrane receptors

Answer 9

1) ion channel receptors
2) kinase receptors
3) heptahelical receptors (GPCR)

Question 10

cytoplasmic receptors

Answer 10

receptor for steroid/thyroid hormore superfamily of receptors

Question 11

nuclear receptors

Answer 11

receptor for signals that affect lipid metabolism ==> target for lipid lowering drugs

Question 12

ion channel receptors and example

Answer 12

can be either voltage gated or ligand gates

-example of nicotinic ACh receptor

Question 13

3 types of kinase receptors

Answer 13

tyrosine kinase
JAK-STAT
serine-threonine kinase

Question 14

function of G proteins in membrane events

Answer 14

Function → when GTP binds to alpha and signal molecule binds to extracellular receptor, then beta and gamma subunit dissociate from alpha subunit → alpha subunit exchanges GDP for GTP and becomes active → the active alpha subunit can further transduce the signal

Question 15

3 types of heterotrimeric G proteins

Answer 15

• ion channels that can be activated by GPCR
• Phosphatidylinositol that can be activated by GPCR
• Tyrosine Kinase receptors that act on GPCR

Question 16

active Ras =

problem with Ras being constantly activated

Answer 16

onward transmission of signal (can be signal for proliferation)

-constantly activated Ras can lead to continuous transmission of signals ==> proliferation ==> uncontrollable cell replication ==> cancer