biochem

• What is gluconeogenesis?

  Production of glucose from non-carbohydrate sources
• Why is gluconeogenesis not a complete reversal of glycolysis?

  It bypasses three high-energy steps with different enzymes
• Where does gluconeogenesis predominantly occur in the human body?

  Liver
• Does gluconeogenesis produce ATP?

  No, it requires an input of energy
• What is the primary function of gluconeogenesis?

  Maintaining blood glucose concentration
• How many ATP, GTP, and NADH are required to form one glucose molecule from pyruvate?

  4 ATP, 2 GTP, and 2 NADH
• Which enzyme catalyzes the conversion of pyruvate to oxaloacetate?

  Pyruvate carboxylase
• What are the key roles of Acetyl CoA in metabolism?

  • Starting metabolite for fatty acid synthesis
  • Enters TCA cycle via condensation with oxaloacetate
• Where does most fat synthesis occur in eukaryotes?

  Cytosol
• Where does fat degradation take place?

  Mitochondria
• From where is acetate for fat synthesis mainly derived?

  Pyruvate
• Can mammals synthesize all-cis-Δ 7,10,13,16,19-docosapentaenoic acid from linoleic acid?

  No, they can't place all double bonds correctly
• Is biotin required for fatty acid synthesis?

  Yes, for conversion of acetyl CoA to malonyl CoA
• Where do oxidative phosphorylation, fatty acid oxidation, and the TCA cycle take place?

  Inner membrane of mitochondria
• What is coenzyme A?

  Nucleotide coenzyme
• How does β-oxidation provide energy for the cell?

  Through oxidative phosphorylation via NADH and FADH2
• What enzyme is required for β-oxidation?

  Δ 2 trans enoyl hydratase
• What do enzymes of the β-oxidation pathway have broad specificities for?

  Chain length of fatty acids
• Is the total energy yield from the oxidation of a C6 fatty acid less than that of a C6 sugar?

  No, it is greater due to more reduced state
• What is the normal duration of a marathon?

  2 hours
• What is one fuel consumed while running a marathon?

  CHO in muscle
• What is the other fuel utilized during a marathon?

  Fat in muscle and adipose tissue
• What happens to the use of carbohydrate and fat in response to exercise and fitness?

  It increases
• What are the key statements regarding ATP production in the TCA cycle and glycolysis?

  • TCA cycle produces more ATP than glycolysis
  • Glycolysis and TCA cycle contribute equally to ATP production in the presence of oxygen
• What is VO2Max?

  Maximal oxygen use
• How does VO2max change in trained versus untrained individuals?

  Goes up in trained runners
• What are the two fates of glucose after conversion to pyruvate?

  Lactate and acetyl CoA
• What process converts fatty acids to acetyl CoA?

  Beta oxidation
• Which mitochondrial membrane-bound complex would you block to stop beta oxidation?

  CPT-1/CAT/CPT-II
• On which ion gradient is ATP production reliant?

  Proton (H+) gradient
• Which cyclical catabolic pathway occurs in the mitochondria of muscle cells?

  TCA cycle
• What are the common metabolic intermediates that amino acid pathways converge to give?

  Pyruvate, oxaloacetate, α-oxoglutarate, acetyl CoA, succinyl CoA
• How does degradation begin for most amino acids?

  By removal of the α-amino nitrogen
• What are the two major routes of deamination?

  Transamination and oxidative deamination
• What is the problem of nitrogen catabolism in terrestrial animals?

  Ammonia is toxic and must be converted to urea
• Summarize the Urea cycle in terms of input, output, and energy expenditure.

  • Input: nitrogen from aspartate and ammonia
  • Output: urea and fumarate
  • Energy expenditure: 4 high-energy phosphate bonds for 1 urea
• What is the sequence of events in the Ubiquitin pathway?

  Involves tagging proteins for degradation
• What is the initially synthesized purine derivative in de novo synthesis?

  IMP
• Which amino acid is required to convert xanthosine monophosphate to guanosine monophosphate?

  Glutamine
• What is the effect of Ribavirin on XMP synthesis?

  Inhibits IMPDH, reducing GMP production