Life in the Beginning

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From the moment we are born we inch towards our demise, life is what happens in between

What is Life

Carbon

When Did Life First Appear on Earth

How did Life First Appear

The First Inhabitants

Building blocks of life are in space

Essential Elements of Life

Window of Opportunity has increased

Panspermia, Comets the Galactic Taxis

What is Life?
A long time ago an extraordinary event happened in the universe. A thing called life arose! It is made up of elementary particles just like everything else around us, and everything else we know of in the universe. But yet it's completely different. But the difference between 'life' and 'non-life' is not due to what they are made of. Because both are made from the same basic ingredients, the same building blocks - combinations of the 92 types of atoms that naturally appear in the universe. But rather the complexity of how these atoms are arranged. But should the origin of life be regarded as an extraordinary event? Is life beyond comprehension? Or is it just an normal anticipated outcome of a collection and interaction of complex molecules?

But what is it that turns these elementary particles into living matter? When did the chemical transition from lifeless substances to a complex system of interacting molecules, that displays behaviour we call 'life', occur? At what stage does matter reach a state we call 'living'? Its difficult to define 'living'. For this discussion we will consider it to be a form of chemistry that must;

  • be able to grow
  • be able to reproduce
  • be subject to Darwinian evolution
  • be able to metabolize - take in energy, use it and release waste products
  • respond to stimuli

Carbon
Life, as we know it, revolves around the chemical element carbon. In the early universe, as some stars reached the end of their life cycle, they exploded, and elements were ejected. One element in particular, carbon, proved to be a remarkable element and went on to play a dominant role in the origin and evolution of life. Its chemical properties allow it to bond with itself as well as a wide variety of other elements. This allowed it to build many different compounds of varing forms, shapes and complexities, and form nearly 10 million known compounds. Many thousands of these are vital to life processes.

Carbon Atom

Carbon has six electrons. And this is what makes it so special. The two innermost are tightly bound to the nucleus. And the remaining four are in the outer shell which 'nature' says should have eight electrons. So in its search for stability, it has a half full shell with four electrons, allowing it to share four electrons or make four separate links with other atoms including atoms of carbon. This is the maximum number of bonds any atom can make (there may be one or two exceptions). There are other atoms that can make four chemical bonds each, such as silicon. But carbon atoms are eigth times more numerous than silicon atoms, and also, the carbon bonds are stronger.

An entire branch of chemistry, organic chemistry, is devoted to the study of the structure, properties, composition and reactions of carbon compounds. Carbon compounds form the basis and are a vital component for all life on Earth. When united with oxygen it forms carbon dioxide which is vital to plant growth. When combined with both oxygen and hydrogen it can form many groups of compounds including fatty acids, which are essential to life.

Carbon is abundant in stars, comets, meteorites and in atmospheres in the solar system. It is the sixth most abundant element in the universe. And because it is so common along with its supreme bonding capability, it plays a dominant role in the chemistry of life.