Energy Metabolism Flashcards
What are the 3 types of energy?
- Potential
- Kinetic
- Chemical
Where does energy come from?
Sun
How is energy derived from the sun?
- Plants photosynthesise sun’s energy (chlorophyll absorbs energy, synthesises H2O & CO2)
- Animals feed on these plants or other animals that have eaten the plant
Why do animals need energy?
- Maintenance
- Growth & synthesis
- Activity
What are the 3 main chemical molecules that break down to produce energy?
- Carbohydrates
- Fatty acids
- Proteins
What happens to the 3 main molecules to produce energy?
- They are oxidised (kreb’s cycle & electron transport chain)
- Produces H2O, CO2, heat & chemical energy in the form of high energy phosphate bonds in ATP
What is ATP? What is it made up of?
- Adenosine triphosphote
- Source of energy for use & storage at the cellular level
- Adenine base, ribose sugar & 3 bonded phosphate groups
What is energy metabolism?
The overall use of ATP by an animal
What is metabolic rate?
Amount of energy used per unit time
What is energy measured in?
Joules (J) or kilojoules (kJ)
What is power measured in?
Watts
What is the basal metabolic rate?
The lowest level of metabolic rate of an animal at rest in a post-absorptive state within its thermal neutral zone (can’t be using energy to generate heat)
What doesn’t rely on the sun for energy?
- Chemoautotrophic bacteria & algae
- Hydrothermal vent organisms
How do hydrothermal vents & chemoautotrophicbacteria/algae obtain energy?
- Oxidation of inorganic compounds
- Animals that eat these compounds
What are ectotherms?
Organisms that depend on external sources for temperature regulation
What are the 3 main ways of measuring energy metabolism?
- Direct calorimetry
- Indirect calorimetry
- Doubly labelled water
What is direct colorometry?
Measures heat production
What is indirect colorometry?
Measures gas exchange: oxygen consumption & carbon dioxide production
Why is it useful to use oxygen consumption to measure metabolic rate?
Litre of O2 consumed is the same irrespective of the substrate oxidised (i.e. carb/protein/fat etc)
What is the disadvantage of using Carbon dioxide as a measure of metabolic rate?
- Large amounts of CO2 stored in blood as bicarbonate
- During anaerobic metabolism, lactic acid in blood flushes CO2 into lungs, where it exhaled
- Not reliable if doing a single measurement as different breathing styles affect how much CO2 is exhaled
What can be used to measure field metabolic rates?
Doubly-labelled water (dlw)
Animals are injected, released & recaptured to analyse blood
What 3 main factors affect rate of energy metabolism?
- Climate (temperature)
- Body size
- Activity
Describe the relationship between energy expenditure & size of an animal
Total energy expenditure increases as size of animal increases
How are relative metabolic rates measured?
- Mass-specific oxygen consumption (oxygen consumed per unit body mass)
