carb metabolism

• What is the largest source of dietary calories for most of the world’s population?

  Carbohydrates
• What is the chemical formula for carbohydrates?

  Cn(H2O)n
• What are carbohydrates composed of?

  Polymers of sugar units
• How can carbohydrates be classified?

  • Monosaccharides
  • Disaccharides
  • Polysaccharides
• What is the most biomedically important carbohydrate?

  Glucose
• What is the universal fuel of human cells?

  Glucose
• What are some compounds synthesized from glucose?

  Glycogen, Ribose, Deoxyribose, Pyruvate
• What is glycolysis?

  • Converts glucose to 3C compounds
  • Provides energy
  • Site: Cytosol of all cells
  • Substrate: Glucose
  • Products: Pyruvate, NADH, ATP
  • RLE: Phosphofructokinase
• What is the first step of glycolysis?

  Formation of Glucose-6-Phosphate
• What enzyme is used in the formation of Glucose-6-Phosphate?

  Hexokinase
• What happens during the phosphorylation of glucose?

  ATP is invested to add phosphate
• What is the second step of glycolysis?

  Formation of Fructose-6-Phosphate
• What enzyme catalyzes the isomerization in glycolysis?

  Phosphoglucoisomerase
• What occurs during the formation of Fructose-6-Phosphate?

  G-6-P is rearranged from a 6-membered ring
• What is the third step of glycolysis?

  Formation of Fructose-1,6-Bisphosphate
• What is the role of Phosphofructokinase in glycolysis?

  It is the rate-limiting enzyme
• What happens during the formation of Triose Phosphates?

  Fructose-1,6-BisP is cleaved into two 3C molecules
• What is the enzyme used in the cleavage of Fructose-1,6-Bisphosphate?

  Aldolase
• What is the fifth step of glycolysis?

  Isomerization of Triose Phosphates
• What enzyme is involved in the isomerization of Triose Phosphates?

  Triosephosphate isomerase
• What is formed during the sixth step of glycolysis?

  1,3-Bisphosphoglycerate
• What occurs during the oxidation and phosphorylation in glycolysis?

  ℗i is added to C3 of Glyceraldehyde-3-P
• What is the enzyme used to form 3-Phosphoglycerate?

  Phosphoglycerokinase
• What happens during substrate-level phosphorylation in glycolysis?

  ℗ is transferred to ADP, forming ATP
• What is the eighth step of glycolysis?

  Formation of 2-Phosphoglycerate
• What enzyme catalyzes the formation of 2-Phosphoglycerate?

  Phosphoglyceromutase
• What is the ninth step of glycolysis?

  Formation of Phosphoenolpyruvate
• What reaction occurs during the formation of Phosphoenolpyruvate?

  Dehydration produces a –C=C– bond
• What is the final step of glycolysis?

  Formation of Pyruvate
• What enzyme is used in the formation of Pyruvate?

  Pyruvate Kinase
• What is the role of ATP in the final step of glycolysis?

  ℗ is transferred to ADP, forming ATP
• What are the control points of glycolysis?

  • Step 1: Hexokinase (inhibited by glucose-6-phosphate)
  • Step 3: Phosphofructokinase (inhibited by citrate, ATP)
  • Step 10: Pyruvate Kinase (inhibited by ATP)
• How is galactose metabolized?

  Converted into glucose-1-phosphate
• What is the metabolic pathway for fructose?

  Phosphorylated to fructose-1-phosphate
• What is gluconeogenesis?

  Glucose from noncarbohydrate sources
• Where does gluconeogenesis occur?

  • Mitochondria & Cytosol
  • Liver & Kidney
• What are the substrates for gluconeogenesis?

  Glycolysis & Krebs Cycle intermediates
• What is the product of gluconeogenesis?

  Glucose
• What is the rate-limiting enzyme of gluconeogenesis?

  Fructose-1,6-bisphosphatase
• What is required for gluconeogenesis?

  Hydrolysis of 4 ATP and 2 GTP