TAILIEUCHUNG - Biochemistry, 4th Edition P74

Biochemistry, 4th Edition P74. Continuing Garrett and Grisham's innovative conceptual and organizing framework, "Essential Questions," BIOCHEMISTRY guides students through course concepts in a way that reveals the beauty and usefulness of biochemistry in the everyday world. Streamlined for increased clarity and readability, this edition also includes new photos and illustrations that show the subject matter consistently throughout the text. New end-of-chapter problems, MCAT practice questions, and the unparalleled text/media integration with the power of CengageNOW round out this exceptional package, giving you the tools you need to both master course concepts and develop critical problem-solving skills you can draw upon. | Problems 693 stimulates protein phosphatase 2A PP2A which dephosphorylates the bifunctional enzyme PFK-2 F-2 6-BPase Figure and see Figure . Increases in fructose-2 6-bisphosphate stimulate glycolysis and inhibit gluconeogenesis. At the same time PP2A dephosphorylates carbohydrate-responsive element-binding protein ChREBP a transcription factor that activates expression of liver genes for lipid synthesis. These effects are a powerful combination. Increased glycolysis produces substantial amounts of acetyl-CoA the principal substrate for lipid synthesis. The pentose phosphate pathway produces NADPH the source of electrons for lipid biosynthesis. Elevated expression of the appropriate genes sets the stage for lipid biosynthesis in the liver an important consequence of ingestion of carbohydrates. SUMMARY What Is Gluconeogenesis and How Does It Operate Gluconeogenesis is the generation genesis of new neo glucose. In addition to pyruvate and lactate other noncarbohydrate precursors can be used as substrates for gluconeogenesis in animals including most of the amino acids as well as glycerol and all the TCA cycle intermediates. On the other hand fatty acids are not substrates for gluconeogenesis in animals. Lysine and leucine are the only amino acids that are not substrates for gluconeogenesis. These amino acids produce only acetyl-CoA upon degradation. Acetyl-CoA can be a substrate for gluconeogenesis in plants when the glyoxylate cycle is operating. The major sites of gluconeogenesis are the liver and kidneys which account for about 90 and 10 of the body s gluconeogenic activity respectively. How Is Gluconeogenesis Regulated Glycolysis and gluconeogenesis are under reciprocal control so glycolysis is inhibited when gluconeogenesis is active and vice versa. When the energy status of the cell is low glucose is rapidly degraded to produce needed energy. When the energy status is high pyruvate and other metabolites are utilized for synthesis and .

• Sinh học
• Nền tảng của hóa sinh học
• trao đổi chất protein
• RNA trao đổi chất
• nguyên tắc của hóa sinh
• Axit amin
• công nghệ DNA