Lipids III

Question 1

Rate limiting step in PC synthesis

Answer 1

Phsophocholine transffered to CTP by phosphocholine cytidltrnsferase

Question 2

PE synthesis

Answer 2

ethaolamine activated by phosphorylation, transferred to CTP. Ethanolamin phosphotransferase transfers ethanoamin to DAG to make PE

Question 3

PS synthesis

Answer 3

phosphatidylserine synthase exchanged head froup of PE to serine

Question 4

What is dicyldlyerol activated by

Answer 4

CTP, not the head group

Question 5

Role of CTP in synthesis of phospholipids

Answer 5

Source of energy and coenzyme for synthesis.

Question 6

Importance of asymmetric distrubtion of lipids between bilayers

Answer 6

during stress in RBCs, an enzyme transfers PS from inner to outer leaflet and this causes recognition by macrophages for cell destruction

Question 7

Phospholipase A1 and A2

Answer 7

remove FAs on C1 and C2 respectively

Question 8

Phospholipase C

Answer 8

removes phosphate head group on C3

Question 9

Why are lipoxygenase inhibitors effective in treatment of asthma

Answer 9

promote smooth muscle contraction in blood vessels, aires and intestine. Slow production of leukotriences which would decrease contraction of aireway

Question 10

role of phospholipiids in prevention of respiraatory distress syndrome in premature infants

Answer 10

Lung surfactant is rich in phospholipids and production of surfactant begins at 31 weeks gestation. Premmeis ahve low lecithin/sphingomyelin ratios, at risk for respiratory distress syndrome which is treated with artificial lung surfactant