NS 3310 1st Edition Lecture 1Outline of Current LectureI. Exams and GradingII. Introduction: CellsIII. Insulin SecretionIV. Biological EnergyCurrent LectureI. Exams and Grading- Quizzes (3 online) 50 pts each, drop one- Prelims (2) 100 pts each- Final (1) 200 pt- Brain buster 20 pts- Attendance 30 pt- Oral presentation 50 ptII. Introduction: Cells- Cell membrane: cells are surrounded by a phospholipid bilayer that contains proteins, carbs, lipids- Golgi: series of membrane sacks that process and package proteins after leaving ER- Lysosome: contains digestive enzymes that break up proteins, lipids and nucleic acids- Smooth ER: lipid synthesis with no ribosome for protein synthesis- Rough ER: series of membrane sacks that contain ribosomes that build and process proteins- Cytoplasm: contains organelles, proteins- Nucleus: contains DNA and genome- Mitochondria: produce most of ATP - Cells receive signals in three waysThese 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.-Signal comes in through a cell surface receptor. Ligand activates receptor and receptor can either directly signal downstream through a mechanism often involving phosphorylation or it can go through a G-protein that activates adenylate cyclase. Adenylate cyclase is responsible for the production of cAMP.-Signal comes in through a channel. Ions enter cell this way because they are chargedso they cannot freely enter the cell. -Extracellular signal can directly come into the cell and bind to receptors inside the cell. Nonpolar molecules can enter the cell this way. III. Insulin Secretion- Insulin secretion after a meal is initiated by a rise in extracellular glucose, which is detected by a metabolic signaling pathway.- Aerobic glycolysis and mitochondrial oxidation produce metabolic signals, such as a rise in the ATP to ADP concentration ratio-This closes potassium-ATP channels, depolarizes the plasma membrane and causes calcium influx that stimulates exocytosis- Additionally, incretin hormones (GLP-1 and GIP) bind to their receptors, which are highly expressed on pancreatic beta cells-Causes activation of G proteins- Glucose and GLP-1 signaling pathways converge on AC8 (an isoform of adenylate cyclase)that is abundant in pancreatic beta cells -Fully activated when both Gαs–GTP and calcium–calmodulin are bound- The rise in cellular cAMP triggers exocytosis by protein kinase A and EPAC2IV. Biological Energy- High energy phosphate in energy storage found in phosphocreatine, phosphoenolpyruvate and 1,3-biphosphoglycerate- Coupled reactions -Favorable reactions can drive unfavorable reactions- ATP is the major storage form of molecular energy in the cell- Energy cannot be created or destroyed; can only be transformed- ATP is derived from nutrients which is then used for muscle contraction, biosynthesis, and active
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