BBMB 405 1nd Edition Lecture 20 Outline of Last Lecture XVII Chapter 25 Nucleotide Biosynthesis B The pyrimidine ring is assembled de novo or recovered by salvage pathways C Purine bases can be synthesized de novo or recycled by salvage pathways D Deoxyribonucleotides are synthesized by reduction of ribonucleotides through a radical mechanism E Key steps in nucleotide biosynthesis are regulated by feedback inhibition F Disruption in nucleotide metabolism can cause pathological conditions Outline of Current Lecture XVIII Chapter 26 The Biosynthesis of Membrane Lipids and Steriods A Phosphatidate is common intermediate in synthesis of phospholipids and triacylglycerols Current Lecture XVIII Chapter 26 The Biosynthesis of Membrane Lipids and Steriods A Phosphatidate is common intermediate in synthesis of phospholipids and triacylglycerols 1 Phosohatidate a First step is to make phosphatidate b These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute c Synthesized in endoplasmic recticulum and outer mitochondrial membrane can be synthesized from diacylglycerol salvage pathway via enzyme diacylglycerol kinase d Acylatins adding acyl catalyzed by glycerol phosphate acyltransferase e f Key enzyme in regulation of lipid synthesis phosphatidic acid phosphatase then use diglyceride acyltransferase reaction below g h Liver is primary site of triacylglycerol synthesis 2 The synthesis of phospholipids requires activated intermediate a Membrane lipid synthesis in endoplasmic recticulum and golgi apparatus phospholipid synthesis requires combination of diacylglycerol with alcohol but one has to be activated b Synthesis from activated diacylglycerol i Start driven by hydrolysis of pyrophosphate ii Activated phosphatidyl unit reacts with hydroxyl group of alcohol to form phosphodiester linkage iii Located exclusively in inner mitochondrial membranes plays role in organization of protein components of oxidative phosphorylation required for full activity of cytochrome oxidatase c Synthesis from an activated alcohol i Activated alcohol CDP ethanolamine ii Enzyme Phosphatidylethanolamine methyltranserase iii Phosphatidylcholine serine choline phosphatidylserine iv Phosphatidylethanolamine serine ethanolamine phosphatidylserine 3 Sphingolipids are synthesized from ceramide a Sphingolipids found in plasma membranes of all eukaryotic cells concentration is highest in cells of central nervous system backbone sphingosine b c d Sphingomyelin component of myelin sheath covering many nerve fibers 4 Gangliosides are carbohydrate rich sphingolipids that contain acidic sugars a Ganglioside oligosaccharide chain linked to terminal hydroxyl group of ceraminde by glucose residue b Crucial for binding immune system cells to sites of injury in inflammatory response
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