Earth’s carbon can be viewed from an even more fundamental perspective: All life’s structures are based on atomic carbon, and the carbon cycle of photosynthesis & cell perspiration creates all of its energy.

Carbon’s unique atomic characteristics underlie the highly versatile building blocks that allow complex life-forms:

1. Tetravalency: Carbon has four valence electrons, allowing it to form up to four covalent bonds with other atoms. This makes it highly versatile in forming complex and stable molecules.
2. Catenation and bonding with other essential elements: Carbon bonds easily with itself (catenation) forming long chains and rings. This ability to form stable chains and cyclic structures is fundamental to the complexity of organic molecules, from simple hydrocarbons to complex proteins and DNA. Carbon also bonds easily with other essential elements such as hydrogen, oxygen, nitrogen, sulfur, and phosphorus. These combinations in turn create key biological molecules like carbohydrates, proteins, lipids, and nucleic acids.
3. Versatility: Indeed, with this ease of bonding carbon forms truly a vast array of compounds, more than any other element. This diversity is crucial and organic molecules can greatly vary in size, shape, and function.
4. Allotropic Forms: Carbon also exists in different allotropic forms, such as graphite, diamond, and fullerenes, each with unique properties. This versatility extends to organic chemistry, where slight changes in molecular structure can lead to vastly different properties and functions.
5. Stability and Reactivity Balance: Carbon compounds are generally stable under a wide range of temperatures and conditions, making them suitable for the diverse environments on Earth. However, at the same time they can undergo wide range of chemical reactions. This balance is essential for metabolic processes, allowing living organisms to build and break down molecules efficiently.
6. Abundance: Carbon is also plentiful on earth and indeed the fourth most abundant element in the solar photosphere (and indeed in known universe, originally created in the centre of aging stars).

In addition to the static building blocks of life, it is the very basic carbon cycle that creates the base energy used by every living organism.

1. Photosynthesis: Plants, algae, and certain bacteria use photosynthesis to convert carbon dioxide, water, and light energy into glucose and oxygen.

• 6 CO₂ + 6 H₂O + light energy → C₆H₁₂O₆ + 6 O₂

2. Respiration: Animals and other organisms release CO₂ back into the atmosphere through respiration where the opposite occurs. In living cells ATP (C₁₀H₁₆N₅O₁₃P₃) is a high-energy molecule that with water can be broken down into ADP (C₁₀H₁₅N₅O₁₀P₂) and inorganic phosphate (HPO₄^2-) to release energy. Cellular respiration regenerates ATP from ADP, producing carbon dioxide and water as by-products.

• C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + ATP

This most basic carbon cycled maintains the ecosystem balance of carbon and thus basic stability of planet’s life.