MCAT Basics (from MedSchoolCoach) Metabolism: Gluconeogenesis, Pentose Phosphate Pathway, and More
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Nov 5, 2024 Explore the intricate world of metabolism, focusing on gluconeogenesis and the pentose phosphate pathway. Discover how your body maintains glucose levels through hormonal regulation by insulin and glucagon. Learn about the vital role of NADPH in anabolic reactions and how glycogen is synthesized and broken down. Delve into the formation of ketone bodies from ketogenic amino acids, crucial during fasting. Plus, get essential MCAT study tips to enhance analytical skills and understanding of these biochemical pathways.
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Pentose Phosphate Pathway Roles
- The pentose phosphate pathway converts glucose 6-phosphate into ribose 5-phosphate and produces NADPH.
- NADPH acts as an electron donor in biosynthesis and antioxidant maintenance, differing functionally from NADH.
Hormonal Control of Glucose
- Insulin is secreted by pancreatic beta cells to reduce blood glucose via GLUT4 transporter insertion.
- Glucagon from alpha cells raises blood glucose by promoting gluconeogenesis, glycogen breakdown, and ketogenesis.
Glycogen Synthesis and Breakdown
- Glycogen synthesis uses UDP-glucose formed by reacting glucose 1-phosphate with UTP.
- Glycogen breakdown by glycogen phosphorylase releases glucose 1-phosphate from non-reducing ends; branches require a debranching enzyme.