What life is


No life without energy

All life depends on the continuous input of energy. Many chemical reactions in our bodies are tuned to extract energy from food and use this energy to make new cells and keep cells already made alive. In this process food molecules play two roles; first, they contain energy that can be converted to forms generally useful for biological reaction; second, they contain molecular structures that can be used to make macromolecules.

The energy for all life originates from the sun. Light energy is converted into chemical energy (organic molecules) in the presence of water and minerals. Some of the captured energy is used to make more biomass (plants) to sustain animal life, provide energy to grow and do work (animals walk around), while some energy is lost as heat and waste molecules. The most effective way of converting chemical energy into useful energy to sustain life is respiration. Warm blooded animals have found ways to use the heat to maintain a relatively high body temperature which gives them an advantage in colder environments.

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 Copyright © 1999-2011 Lukas K. Buehler