Week 6 Signals

Question 1

Signals, cofactors & pigments

Answer 1

Family of lipids that have active roles – metabolites and messengers
— Hormones
— Enzyme cofactors
— Pigment molecules – absorb visible light

Question 2

Phosphatidylinositol’s – in signalling

Answer 2

Phosphatidylinositol 4,5-bisphosphate (PIP2)
—Located in cytoplasmic face of plasma membranes
— Reservoir of messenger molecules
—Formation of inositol 1,4,5-triphosphate (IP3)
— Important in muscle contraction

Phosphatidylinositol 3,4,5-triphosphate
Pip2 can be broken down into ip3
Phosoporalated into pip 3 = useful for glucose transporters

Question 3

Eicosanoids

Answer 3

Eicosanoids – paracrine hormones
— All derived from arachidonic acid
— Roles in reproduction, inflammation, fever, pain, formation of blot clots, blood pressure regulation, gastric acid secretion ……
— Three classes
— Prostaglandins (PG) - causes inflammatory response,swelling, regulation of temperature, production of acid in the stomach
— Thromboxanes
— Leukotrienes

Enzymatic oxidation of arachidonic acid yields
—Prostaglandins
— Elevate temperature (fever)
— Affects blood flow
— Contraction of smooth muscle in menstruation & labour

— Thromboxanes
— Produced by platelets
— Role in formation of blood clots
— Reduce local blood flow

— Leukotrienes
— Contraction of smooth muscle in lung
— Contraindicated in asthmatics & anaphylactic shock

Question 4

Steroid hormones

Answer 4

Oxidised derivatives of sterols
Move through the bloodstream bound to plasma proteins
4 carbon ring
Oxidised derríbate d of cholesterol
Can pass through plasma membrane
Lipifilic profile

Corto sol

Question 5

Vitamins

Answer 5

Water soluble - vitamin B group, vitamin C

Fat soluble- Vitamin A, D,E,K

Can be considered as a hormone
Vitamin d can be stored up to 3 months in liver then metabolised to circulate into more active form

Question 6

Vitamin D

Question 7

Vitamin A

Answer 7

Lipid vitamin
Oxidation of carbon 15 retinol > retinal
Retinoic acid > signal to epthilal cell