Metabolic integration

• What is the focus of Chapter 7 in the study material?

  The breakdown of glucose and metabolic integration
• What happens to excess glucose in the cell?


  It is stored as glycogen in animals and starch in plants
• What are the two major forms in which glucose can be stored?

  Glycogen in animals and starch in plants
• What is glycogen composed of?


  A large, branched chain of glucose molecules attached to a central protein
• Where is starch found?


  In plants such as potatoes, wheat, and corn
• How are carbohydrates in the animal diet processed?


  They are broken down into glucose and other simple sugars
• What happens to blood glucose levels after a meal?


  They increase, leading to the formation of glycogen
• What is the role of glycogen stored in muscle cells?


  It provides ATP for muscle contraction
• How does the liver utilize glycogen?


  It serves as a glycogen storehouse for the whole body
• What happens to glucose molecules cleaved from glycogen?


  They are released as glucose 1-phosphate
• What is the conversion process of glucose 1-phosphate?


  It is converted into glucose 6-phosphate, an intermediate in glycolysis
• How many ATP molecules are produced from one glucose molecule cleaved off a glycogen chain?


  Three ATP molecules
• What are disaccharides?


  Carbohydrates with two sugar units
• What happens to disaccharides in the diet?


  They are hydrolyzed into monosaccharides
• How do sugars other than glucose enter glycolysis?


  They are converted into intermediates of glycolysis
• What is the process that converts fructose into glycolysis intermediates?


  Fructose is phosphorylated to form fructose 6-phosphate or fructose 1-phosphate
• What is the end product of fatty acid breakdown?

  Acetyl-CoA, which feeds the citric acid cycle
• What is β-oxidation?


  A process that shortens fatty acids by removing two carbon units
• What do fatty acids produce during β-oxidation?


  NADH and FADH₂ molecules
• How much ATP is produced from the complete oxidation of palmitic acid?


  About 106 molecules of ATP
• Why are fatty acids considered an efficient source of energy?


  They produce a large amount of ATP during oxidation
• Which tissues primarily depend on glucose for energy?


  The brain and red blood cells
• How are proteins utilized for energy?


  They are broken down into amino acids that enter metabolic pathways
• What does the intracellular level of ATP indicate?


  How much energy a cell has available
• What happens when ATP levels are high in a cell?


  Pathways that generate ATP are slowed down
• What is the effect of high NADH levels on cellular respiration?


  They inhibit cellular respiration
• How does the cell coordinate its metabolic responses?


  By regulating enzymes that control key steps of metabolic pathways
• What is the significance of the reaction catalyzed by phosphofructokinase-1 (PFK-1)?


  It is a key, irreversible step in glycolysis and is tightly controlled
• What role does PFK-1 play in glycolysis?


  It acts as a metabolic valve that regulates the rate of glycolysis
• What are the main metabolic pathways for breaking down fuel molecules?

  1. Glycolysis
  2. Pyruvate oxidation
  3. Citric acid cycle
  4. Oxidative phosphorylation
• What are the storage forms of glucose in animals and plants?

  • Glycogen in animals
  • Starch in plants
• What are the types of sugars produced from carbohydrates in the diet?

  • Monosaccharides (e.g., fructose, galactose)
  • Disaccharides (e.g., maltose, sucrose, lactose)
• What are the sources of energy for cellular respiration?


  • Glucose
  • Fatty acids
  • Proteins
• What are the key regulators of cellular respiration?


  • ATP levels
  • NADH levels
  • Enzyme regulation
• What effect do high NAD levels have on cellular respiration?


  They stimulate cellular respiration.
• What effect do high NADH levels have on cellular respiration?


  They inhibit cellular respiration.
• What is one mechanism that allows coordinated cellular responses?


  The regulation of enzymes that control key steps of the pathway.
• What is the third reaction of glycolysis?


  Fructose 6-phosphate is converted to fructose 1,6-bisphosphate.
• Why is the third reaction of glycolysis considered a "committed" step?


  It is highly endergonic and irreversible.
• What enzyme catalyzes the third reaction of glycolysis?


  Phosphofructokinase-1 (PFK-1).