Metabolism & thermoregulation

• The 3 major uses of ATP in animal cells are: Biosynthesis, Mechanical Work and Transport work
• 2 kind of energy-yielding metabolic pathways:

  1. aerobic metabolism - presence of oxygen (38 mol of ATP per mol glucose)
  2. anaerobic metabolism - absence of oxygen (2 mol of ATP per mol of glucose)
• Animals use chemical energy from food to produce:

  1. electrical, ionic and osmotic gradients
  2. synthesise metabolites
  3. carry out work via muscle contraction
• ATP is the main source of energy used by animals.
• Conditions of BMR measurements:

  • quiet, resting and fasting condition
• BMR = basal metabolic rate
• Metabolic rate can be measured using:

  • indirect calorimetry
  • direct calorimetry
  • Radioisotopes
  • Respirometry
• Direct Calorimetry measures heat loss
• Indirect Calorimetry measures O2 consumption and CO2 production
• Briefly explain how the doubly-labelled water method can be used to measure metabolic rate:

  • tracking atom movements
  • animals fed with D2 18O for a few days
  • D2 excreted from body by urea
  • 18O excreted by water and CO2
  • determine isotopic ratio, amount of CO2 produced measured
• What do Respirometry method measured?

  gas exchange (o2 / co2)
• RQ of carbohydrates, fats and protein?

  Carbohydrates - 1, fats - 0.70, proteins - 0.80
• what is temperature always associated with?

  enzymes
• For every 10-degree celsius change in temperature, there is a 2-3 fold increase in metabolic activity.
• Ectothermic animals that show temperature independence have enzyme systems with broad temperature range/optima
• Natural selection leads to adaptation, whereas physiological adjustment to the environment within the lifetime of an individual is called acclimation
• Regulation of enzyme activity included:

  • regulate temperature sensitivity
  • change the concentration of relevant substrates
  • modify the energy supply for the reaction
  • alter the pH
• what is role of molecular chaperones?


  acts as protein folding chaperones, involved in stress related response and bring about cross tolerance
• what is ectotherms?


  rely on the environment for control of body temperature
• what are heterotherms?


  Animals that can regulate their body temperature internally but may allow it to fluctuate based on external conditions.
• 3 mechanisms allow insects to warm up thorax prior flight

  • metabolic futile cycle in carbohydrate metabolism
  • muscle contraction (of 2 antagonistic flight muscles)
  • wing movement
• Explain how the countercurrent heat exchange mechanism allows penguins to withstand walking on snow and ice.

  arteries and veins in close contact and blood flows in opposite directions. Artery transfers heat to vein and hence it cools down. Venous blood warmed and returned to the core. Less heat is lost to the environment.