Prostaglandins and leukotrienes -Eicosanoids. -Potent paracrine effects -Cannot travel long distances FATTY ACIDS -Long hydrocarbon chains with a terminal carboxylate (COO-) group. -Highly reduced – energy dense. -MUFA: mono-unsaturated fatty acids -PUFA: poly-unsaturated fatty acids -Naturally occurring Fatty Acids are cis not trans -Industrial production of MUFA + PUFA fats/oils – yield trans isomer fats. omega (last) = w The position of the C=C double bond can be denoted: -In relation to the C number (1st C is the C atom of the COO-) -In relation to the omega C atom e.g. w3 would be 3 carbons back from the omega carbon. Saturated fat – no C=C double bonds Palmitic Acid = C16 Stearic Acid = C18 -solid at room temperature. Unsaturated fat – contains C=C double bonds Oleic acid = monounsaturated fatty acid ---> trans isomer = Elaidic acid Linoleic acid = polyunsaturated fatty acid (more than 1 C=C double bond – 2 double bonds) -Unsaturated fats allow membrane to be more fluid. -They bend and pack in a less ordered way. -liquid at room temperature. EPA: Eicosapentaenoic acid – 5 double bonds DHA: Docosahexenoic acid – 6 double bonds Essential fatty acids PU fatty acids that have more than 2 C=C bonds at least 1 of which is beyond C9. -Linolenic acid (C18:3) – omega 3 fatty acid -Converted to arachidonic acid – ARA (C20:4) -Linoleic acid (C18:2) – omega 6 fatty acid -Converted to eicosapentaenoic acid (C20:5) – EPA -ARA and EPA are used to synthesise eicosanoids. Eicosanoids (prostaglandins and leukotrienes) -Derived from C20 PUFAs – ARA, ESA and EPA. -Synthesis pathways -cyclooxygenase (COX) pathway – prostaglandins and thromboxane. -lipoxygenase (LOX) pathway – leukotriene. -Bind specific plasma membrane receptors. -Functions as local signalling molecules. -Play important roles in: *Inflammation – COX2 inhibtors are widely prescribed NSAIDs e.g. aspirin *Regulation of vascular tone, Triacylglycerides -3C alcohol = Glycerol. -Stored in adipose tissue -1g of triglycerides yields 38kJ of energy. -No solvation – takes up less space than CHO. Lipases: cleave ester bonds of triglycerides to release fatty acids. GlyceroPhospholipids (GPLs) -Simplest GPL is phosphatidate. -It is glycerol 3 phosphate esterified with 2 FA (diacylglycerol) with phosphate group attached to the 3rd OH group. Polar alcohol compounds can be esterified to the PO4 group -Choline – Phosphatidylcholine – major component of biological membranes. -Serine -Ethanolamine -Inositol ---> sugar alcohol – makes neurotransmitters and steroid hormones bind to their receptors in the brain, important in cell signal transduction. -Glycerol: C3 alcohol. GPLs are composed of fatty acid, glycerol, phosphate and alcohol. -Phospholipases breakdown GPLs. Phospholipase A2 (snake venom) - cleaves the SN-2 acyl chain, releasing arachidonic acid. -Lysolecithin:- breakdown product of this reaction, biological detergent, dissolves the membranes of red blood cells causing them of rupture. GPL Properties -Amphipathic molecules. -Polar PO4 and alcohol groups: polar head -Non-polar hydrophobic FA chains: non-polar tail -Integral to the role of GPL in biological membranes. Cholesterol increases membrane fluidity deep in membrane. Cholesterol decreases membrane fluidity near surface. Glycolipids -Main class is Glycosphingolipids – simplest glycosphingolipid is a ceramide. -They’re abundant in nerve cell membranes. -Nerve impulse transmission. -Cell-cell recognition. -Molecular recognition – binds glycoprotein hormones & bacterial toxins. -Sphingolipidoses: defects glycosphingolipid metabolism – fatal neurological disorders. -Membrane lipids based on an 18C amino alcohol rather than glycerol. -Parent compound is ceramide.