The secret of life: What enables its perpetuation

[Bernard NebelKeymaster]

This concept of chemical reactions going in both directions — yielding energy as they spontaneously go in one direction but requiring energy input to go the other — underlies the existence of all life on earth. Only the molecules involved are more complex

Bodies of all plants, animals, fungi, and microbes are constructed form organic molecules (molecules in which covalently bonded carbon atoms form the basic structure of the molecule); proteins, fats/lipids, carbohydrates, and nucleic acids are the basic categories of organic molecules. Many reactions are involved in both the synthesis and breakdown of these molecules. In every case, however, it requires energy to synthesize these molecules and energy is released by their breakdown. The key molecule at the crossroads of all these molecules (both their synthesis and their breakdown) is the 6-carbon sugar, glucose, C₆H₁₂O₆. 

Its breakdown with oxygen releases energy. (Google/find the molecular structure of glucose and model this reaction with your kits.)

        C₆H₁₂O₆   +  6O₂       —>    6CO₂   +    6H₂O     +     energy.              (This reaction has the name, respiration, since the  O₂ is supplied by our breathing.)

Consider glucose as the food you eat; oxygen is in the air you breath. It is this reaction that provides your body with all the energy it constantly needs to maintain the living state, pumping blood, breathing, etc. Additionally, it provides the energy for any and all physical movements and all sorts of brain activity. 

Could life exist on this reaction alone? (Think time) It will be self-evident that life would come to a halt as it ran out of fuel (glucose) for energy. But, life on earth developed a solution — plants and photosynthesis. The cells of green plants have small bodies called chloroplasts, which are microscopic solar cells (type into your browser: chloroplast images) They absorb light energy and use it, through a complex series of chemical reactions, to synthesize glucose from carbon dioxide and water; oxygen is given off as byproduct. Yes, it is the exact reverse of the above reaction, respiration 

     6CO₂   +    6H₂O     +     energy     —>    C₆H₁₂O₆   +  6O₂                 

               (Overall reaction for photosynthesis)

These two reactions, photosynthesis and respiration, are at the heart of all life on earth. Together they provide for a continual recycling of carbon, hence the continuance of life on earth. This is all portrayed in the following video.

 

 

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