BBMB 405 1nd Edition Lecture 20 Outline of Last Lecture XVII. Chapter 25: Nucleotide BiosynthesisB. The pyrimidine ring is assembled de novo or recovered by salvage pathwaysC. Purine bases can be synthesized de novo or recycled by salvage pathwaysD. Deoxyribonucleotides are synthesized by reduction of ribonucleotides through a radical mechanismE. Key steps in nucleotide biosynthesis are regulated by feedback inhibitionF. Disruption in nucleotide metabolism can cause pathological conditionsOutline of Current Lecture XVIII. Chapter 26: The Biosynthesis of Membrane Lipids and SteriodsA. Phosphatidate is common intermediate in synthesis of phospholipids and triacylglycerolsCurrent LectureXVIII. Chapter 26: The Biosynthesis of Membrane Lipids and SteriodsA. Phosphatidate is common intermediate in synthesis of phospholipids and triacylglycerols1. Phosohatidate:a. First step is to make phosphatidateb.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 acyltransferasee.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 synthesis2. The synthesis of phospholipids requires activated intermediatea. Membrane lipid synthesis in endoplasmic recticulum and golgi apparatus, phospholipid synthesis requires combination of diacylglycerol with alcohol but one has to be activatedb. Synthesis from activated diacylglyceroli. Start: driven by hydrolysis of pyrophosphateii. Activated phosphatidyl unit reacts with hydroxyl group of alcohol to form phosphodiester linkageiii. Located exclusively in inner mitochondrial membranes, plays role in organization of protein components of oxidative phosphorylation, required for full activity of cytochrome oxidatasec. Synthesis from an activated alcoholi. Activated alcohol: CDP-ethanolamineii. Enzyme: Phosphatidylethanolamine methyltranseraseiii. Phosphatidylcholine + serine choline + phosphatidylserineiv. Phosphatidylethanolamine + serine ethanolamine + phosphatidylserine3. Sphingolipids are synthesized from ceramidea. Sphingolipids: found in plasma membranes of all eukaryotic cells, concentration ishighest in cells of central nervous system, backbone: sphingosineb.c.d. Sphingomyelin: component of myelin sheath covering many nerve fibers4. Gangliosides are carbohydrate-rich sphingolipids that contain acidic sugarsa. Ganglioside: oligosaccharide chain linked to terminal hydroxyl group of ceramindeby glucose residueb. Crucial for binding immune system cells to sites of injury in inflammatory
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