finals

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

  Carbohydrates
• What is the chemical formula representation for carbohydrates?

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

  Polymers of sugar units
• How can carbohydrates be classified?

  • Monosaccharides
  • Disaccharides
  • Polysaccharides
• What is the chemical formula for glucose?

  C6(H2O)6
• Why is glucose considered the most biomedically important carbohydrate?

  It is the universal fuel of human cells
• What are some compounds synthesized from glucose?

  Glycogen, Ribose, Deoxyribose, Pyruvate
• What is glycolysis and its main function?

  • Converts glucose to 3C compounds
  • Provides energy
  • Known as Embden-Meyerhof-Parnas pathway
• Where does glycolysis occur?

  Cytosol of all cells
• What is the substrate for glycolysis?

  Glucose
• What are the products of glycolysis?

  Pyruvate, NADH, ATP
• What is the rate-limiting enzyme (RLE) of glycolysis?

  Phosphofructokinase
• What are the steps of glycolysis and their key reactions?

  1. Formation of Glucose-6-Phosphate (Phosphorylation)
  2. Formation of Fructose-6-Phosphate (Isomerization)
  3. Formation of Fructose-1,6-Bisphosphate (Phosphorylation)
  4. Formation of Triose Phosphates (Cleavage)
  5. Isomerization of Triose Phosphates (Isomerization)
  6. Formation of 1,3-Bisphosphoglycerate (Oxidation & Phosphorylation)
  7. Formation of 3-Phosphoglycerate (Substrate-level Phosphorylation)
  8. Formation of 2-Phosphoglycerate (Isomerization)
  9. Formation of Phosphoenolpyruvate (Dehydration)
  10. Formation of Pyruvate (Substrate-level Phosphorylation)
• What happens in Step 1 of glycolysis?

  Glucose is phosphorylated to form Glucose-6-Phosphate
• What enzyme catalyzes the formation of Glucose-6-Phosphate?

  Hexokinase
• What is the reaction in Step 2 of glycolysis?

  Isomerization of Glucose-6-Phosphate to Fructose-6-Phosphate
• What enzyme is responsible for the isomerization in Step 2?

  Phosphoglucoisomerase
• What occurs in Step 3 of glycolysis?

  Fructose-6-Phosphate is phosphorylated to Fructose-1,6-Bisphosphate
• What is the rate-limiting enzyme in Step 3 of glycolysis?

  Phosphofructokinase
• What is the reaction in Step 4 of glycolysis?

  Cleavage of Fructose-1,6-Bisphosphate into two 3C molecules
• What enzyme catalyzes the cleavage in Step 4?

  Aldolase
• What happens in Step 5 of glycolysis?

  DHA-P is rearranged to form Glyceraldehyde-3-P
• What enzyme is involved in Step 5 of glycolysis?

  Triosephosphate isomerase
• What occurs in Step 6 of glycolysis?

  Oxidation and phosphorylation of Glyceraldehyde-3-P to form 1,3-Bisphosphoglycerate
• What enzyme catalyzes the reaction in Step 6?

  Glyceraldehyde 3-phosphate dehydrogenase
• What is the reaction in Step 7 of glycolysis?

  Substrate-level phosphorylation to form 3-Phosphoglycerate
• What enzyme is responsible for the reaction in Step 7?

  Phosphoglycerokinase
• What happens in Step 8 of glycolysis?

  Isomerization of 3-Phosphoglycerate to 2-Phosphoglycerate
• What enzyme catalyzes the reaction in Step 8?

  Phosphoglyceromutase
• What occurs in Step 9 of glycolysis?

  Dehydration to form Phosphoenolpyruvate
• What enzyme is involved in Step 9 of glycolysis?

  Enolase
• What happens in Step 10 of glycolysis?

  Substrate-level phosphorylation to form Pyruvate
• What enzyme catalyzes the reaction in Step 10?

  Pyruvate Kinase
• What are the control points of glycolysis and their inhibitors?

  • 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, then glucose-6-phosphate
• How is fructose metabolized?

  Phosphorylated to fructose-1-phosphate, then split into trioses
• What is gluconeogenesis and its conditions?

  • Glucose from noncarbohydrate sources
  • Occurs in mitochondria & cytosol of liver & kidney
  • Conditions: replenishing liver glycogen, converting lactate to glucose, maintaining blood glucose
• What is the rate-limiting enzyme of gluconeogenesis?

  Fructose-1,6-bisphosphatase
• What substrates are used in gluconeogenesis?

  Glycolysis & Krebs Cycle intermediates, lactate, glycerol, glucogenic AAs
• What is required for gluconeogenesis?

  Hydrolysis of 4 ATP and 2 GTP molecules