Lipids as biosignaling

Question 1

glycerophospholipids are precursors of what

Answer 1

inositol- phosphates

Question 2

what does Phospholipase C (activates by an extracellular enzyme) to the phosphotylinositol 4,5-biphosphate

Answer 2

it will hydrolyze it and IP3 (inositol 1,4,5-triphosphate) and DAG (diacylglycerol) are create

Question 3

what does PI3Kinase to the phosphotylinositol 4,5-biphosphate

Answer 3

it phosphorylates it and PIP3 is create

Question 4

what do ceramide and sphingomyelin

Answer 4

ceramide acts as a lipids rafts

sphingomyelin insulate nerve axons

Question 5

eicosanoids are paracrine factors, what is it

Answer 5

paracrine hormones: substances that act only on cells near the point of hormone synthesis instead of being transported in the bloodto act on cells in other tissues or organs

Question 6

basic precursor of eicosanoids

Answer 6

arachidonate, which is released from glycerophospholipids (phospholipase A2)

Question 7

3 eicosanoids

Answer 7

prostaglandins, thormboxanes, leukotrienne

Question 8

role of prostaglandins (3)

Answer 8

smooth muscle contraction
regulate blood flow
regulate body temperature

Question 9

role of thromboxanes (2) + where they come from

Answer 9

they come from platelets

form blood clot and reducing blood flow

Question 10

what are NSAIDs + 2 examples

Answer 10

they inhibit cycloxigenase enzyme (COX1 and 2), it is the enzyme in the beginning of the arachidonate (the enzyme prostaglandin H2 synthase) which catalyze an early step in the patway from arachidonate to prostaglandins or thromboxanes
- ex: aspirin and ibuprofen/

Question 11

what is the role of leukotrienes

Answer 11

airway smooth muscle contraction

Question 12

consequence of a too high concentration of leukotrienes

Answer 12

ot blocks the muscle contraction (that’s why we have difficulty to breath, cause ashtma and anaphylactic shock)

Question 13

what do prednisone

Answer 13

it inhibits phospholipase 2, thus used in Ashtma, Arthrisis, Organ Transplantation…

Question 14

eicosanoids are whcich type of receptor

Answer 14

GPCR proteins

Question 15

5 signaling molecules

Answer 15

1. Hormone: any biomolecule or chemical that elicits a cellular response by sending out a signal, acts far away from the site of its release
   
   2. Paracrine: any signaling molecule or hormone that signals any to nearby cells, no to far away cells
   3. Autocrine: any signaling molecule that acts on the cell that produced it
   4. Juxtacrine: any signaling molecule, the ligand that is produced by a cell and acts only on the immediately adjacent cell that has the receptor for this ligand
      ** both the ligand and the receptor must be cell membrane proteins
      Pheromene: any volatile substance produced in the individual that signals to another individual

Question 16

types of signaling molecules (3)

Answer 16

Amino acids (ex: neurotransmetteurs)
Proteins (ex: insulin)
Lipids (ex: testosterone)

Question 17

4 sterol lipids + type of receptor

Answer 17

** all derived from cholesterol
testosterone, estradiol, cortisol, aldosterole
** nuclear receptors

Question 18

precursor of Vitamin D

Answer 18

7-dehydrocholesterol

Question 19

what happens from 7-dehydrocholesterol to 1a,25-dihydrovitamin D3 (calcitrol)

Answer 19

1. there is a phytochemical reaction between the UV component of sunlight and the 7-dehydrocholesterol and it will create vitamin D3 (or cholecalciferol) which is inactive
2. it will be convert by enzymes in the liver and kidney into 1a,25-dihydroxyvitamin D3 (calcitriol)

Question 20

what do calcitriol (1a,25-dihydroxyvitamin D3)

Answer 20

regulates calcium uptake in the intestine and calcium levels in kidney and bone
so Ca absorption (intestine), Ca exctretion (kidney), Ca storage (bone)

Question 21

the precursor of Vit A and its 2 derivative

Answer 21

precursor: B-carotene
derivatice:
1. retinoic acid: hormonal signal (change in gene expression)
2. retinal: neuronal signal (vision)

Question 22

nuclear receptor of vitamin A

Answer 22

retonoic acid receptor (RAR) ; retinoid X receptor (RXR)

Question 23

7 tocopherols (any several forms of Vitamin E)

Answer 23

vitamin E
Vitamin K1
warfarin
ubiquinone
plastoquinone

Question 24

what is Vitamin E + reacts with what

Answer 24

• an antioxidant
• the aromatic rings reacts with and destroys the most reactive form of oxygen radicals and other free radicals, protecting unsaturated fatty acids from oxidation and preventing oxidative damage to membrane lipids

Question 25

what is Vitamin K1

Answer 25

a blood-clotting cofactor (cofactor to prothrombin)

Question 26

what is warfarin

Answer 26

• a blood anticoagulant- it is a synthetic compund that inhibits prothrombin)

Question 27

role of ubiquinone and plastoquinone

Answer 27

ubiquinone: a mitochondrial electron carrier (coenzyme Q)
plastoquinone: a chloroplast electron carrier