Glucose Metabolism & Glycolysis Notes - Memm PDF

5/30/23, 1:10 AM Study | Memm Cards Glucose metabolism General metabolism Glucose transporters Transported by active transport in the gut and facilitated diffusion elsewhere. The GLUT transporter proteins help with transport. GLUT-2 Located in pancreas and liver tissues. Has a high Km (low aff...

5/30/23, 1:10 AM Study | Memm Cards Glucose metabolism General metabolism Glucose transporters Transported by active transport in the gut and facilitated diffusion elsewhere. The GLUT transporter proteins help with transport. GLUT-2 Located in pancreas and liver tissues. Has a high Km (low affinity). Only transporter that is bidirectional (glucose going both into and out of cells). GLUT-4 Found in adipose and muscle tissues. Has a low Km (high affinity). The only transporter that requires stimulation by insulin. Key enzymes of gluconeogenesis Glucose 6-phosphatase Converts glucose 6-phosphate to glucose through a hydrolysis reaction. Bypasses the glucokinase/hexokinase step from glycolysis. Found only in the liver. Fructose-1,6-bisphosphatase Converts fructose 1,6bisphosphate to fructose 6phosphate, bypassing PFK-1. Activated by ATP, glucagon and inhibited by AMP, insulin. https://memm.io/study/?schedule=cldyyf2ad122421gl3ehjrotix 1/7 5/30/23, 1:10 AM Study | Memm This is the rate-limiting step of gluconeogenesis. Join the Memm Newsletter! Converts pyruvate to Pyruvate carboxylase oxaloacetate which leaves the Subscribe to get our latest MCAT content by by email. mitochondria. Activated acetyl-CoA. Your email address Pyruvate carboxylase and Subscribe fructose-1,6-bisphosphatase are the main regulatory enzymes. We'll never spam you. Unsubscribe any time. Phosphoenolpyruvate Converts oxaloacetate to PEP. carboxykinase (PEPCK) Works with pyruvate carboxylase to bypass pyruvate kinase from glycolysis. Key enzymes of glycolysis Glucokinase Catalyzes conversion of glucose to G6P in the pancreas and liver. The initial step of glycolysis. Prevents glucose from escaping through its conversion. Hexokinase Catalyzes conversion of glucose to G6P in the peripheral tissues. Inhibited by feedback from G6P (its product). Phosphofructokinase-1 Catalyzes conversion of F6P → F-1,6BP with ATP → ADP. Inhibited by signals of high https://memm.io/study/?schedule=cldyyf2ad122421gl3ehjrotix 2/7 5/30/23, 1:10 AM Study | Memm energy: ATP and citrate. Activated by low energy signal AMP orNewsletter! F-2,6BP. Join the Memm The rate-limiting step of glycolysis. Subscribe to get our latest MCAT content by email. Phosphofructokinase-2 Your email address Catalyzes production of F-2,6BP which allows continued activation of PFK-1 in the liver even with abundance of ATP. We'll never spam you. Unsubscribe any time. Activated by insulin and inhibited by glucagon. Pyruvate kinase Performs substrate-level phosphorylation, specifically conversion of phosphoenolpyruvate (PEP) to pyruvate with ADP to ATP. This enzyme is a transferase that transfers an inorganic phosphate onto ADP. Activated by F-1,6BP whose production is catalyzed by PFK1. Inhibited by its product ATP. Glyceraldehyde-3-phosphate Produces NADH which is the (G3P) dehydrogenase substrate for the electron transport chain under aerobic conditions. Principles of gluconeogenesis The production of glucose from carbon substrates (like pyruvate). Think of this as the inverse of glycolysis. Bypassing glycolysis The reversible reactions of glycolysis use the same enzymes in gluconeogenesis while the irreversible reactions of glycolysis are bypassed by https://memm.io/study/?schedule=cldyyf2ad122421gl3ehjrotix 3/7 5/30/23, 1:10 AM Study | Memm different enzymes. • Pyruvate kinase is bypassed by PEPCK Newsletter! and pyruvate Join the Memm carboxylase. • PFK-1 is bypassed by fructose Subscribe to get our latest MCAT content by email. 1,6-bisphosphatase. • Hexokinase is bypassed by Your email address Hormone regulation glucose-6-phosphatase. Activated by glucagon and We'll never spam you. Unsubscribe any time. cortisol. Inhibited by insulin. Rate-limiting step Catalyzed by fructose 1,6bisphosphatase. Location Within the cell, occurs in the cytoplasm and mitochondria. In terms of organ location, primarily in the liver with some occurring in kidneys. Steps of glycolysis Step Conversion Coupled rxn Key enzyme Enzyme type 1 Glucose → ATP → ADP Hexokinase Kinase G6P 2 G6P → F6P 3 F6P → F-1,6BP 4 F-1,6BP → Isomerase ATP → ADP PFK-1 Kinase Lyase GADP + DHAP 5 DHAP → Isomerase GADP 6 GADP → 1,3 NAD → NADH Oxidoreductase ADP → ATP Kinase BPG 7 1,3 BPG → 3PG https://memm.io/study/?schedule=cldyyf2ad122421gl3ehjrotix 4/7 5/30/23, 1:10 AM Study | Memm 8 3-PG → 2-PG Mutase 9 2-PG → PEP Produces H2O Enolase Lyase 10 PEP → ADP → ATP Pyruvate kinase Kinase Join the Memm Newsletter! Pyruvate Subscribe to get our latest MCAT content by email. Principles of glycolysis Your email address Overall reaction Glucose + 2NAD+ + 2ADP + 2P → 2 Pyruvate + 2 ATP (net) + 2 We'll never spam you. Unsubscribe NADH + 2 H+ any time. Enzymes of irreversible steps The kinases glucokinase, hexokinase, PFK-1, and pyruvate kinase catalyze irreversible reactions. Mnemonic: Go Help one Persistent Person Link to other pathways Glucose-6-phosphate from the glycolysis pathway is the primary substrate for glycogenesis. DHAP is used for fatty acid synthesis. Key step Fructose-6-phosphate → fructose-1,6-bisphosphate, catalyzed by PFK-1. This is the rate-limiting step as well as the committed step (can no longer be redirected to glycogenesis pathway). Anaerobic conditions In absence of oxygen, pyruvate must be converted to lactic acid to regenerate NAD+. Overall pathway Glucose → G6P → F6P → F1,6BP → GADP + DHAP → https://memm.io/study/?schedule=cldyyf2ad122421gl3ehjrotix 5/7 5/30/23, 1:10 AM Study | Memm 1,3BPG → 3PG → 2PG → PEP → Pyruvate Join the Memm Newsletter! Subscribe to get our latest MCAT content by email. Your email address We'll never spam you. Unsubscribe any time. Cards © 2023 Memm Inc. Help About Terms Privacy Contact Memm Product Testimonials Comparison with Anki Features FAQ Community Discord Blog https://memm.io/study/?schedule=cldyyf2ad122421gl3ehjrotix 6/7 5/30/23, 1:10 AM Study | Memm Newsletter Join the Memm Newsletter! Subscribe to get our latest MCAT content by email. Your email address We'll never spam you. Unsubscribe any time. https://memm.io/study/?schedule=cldyyf2ad122421gl3ehjrotix 7/7