Life’s purpose is to reproduce. This is most strongly supported by Darwin’s theory of evolution by means of natural selection, and survival of the fittest. Evolution is caused by the mutation of genes, genes being sections of DNA that contain the blueprints for proteins. All proteins are built from the same two-twenty proteinogenic amino acids. The fittest organisms survive and in-turn reproduce more and for a longer lifetime. Passing on the genes of the survivors.
How was life on earth created? To understand this, we need to go back to the first single celled organisms.
Amino Acids & Nucleic Acids - The Building Blocks of Life
If we were to travel back in time around 3.5 billion years we would discover that life on earth stemmed from a pool of twenty-two proteinogenic amino acids and nucleic acids (DNA & RNA). Amino acids are individual organic molecules that structure every protein in living organisms, and nucleic acids are biomolecules made of nucleotides that store and record information, most notably protein sequences.
The Central Dogma of Biology - DNA to RNA to Protein
The absolute simplest way of explaining the flow of genetic information is the Central Dogma, termed by Francis Crick in 1958. The dogma states that DNA is transcribed into a strand of RNA, the RNA is then transported from the nucleus of the cell into a ribosome in the cytoplasm of the cell. In the ribosome the RNA strand is translated, building the specified protein from individual amino acids. DNA makes RNA, and RNA builds protein this system is ubiquitous throughout all living organisms.
Proteins - The Tools for Survival
There are thousands of proteins inside us, and without them we simply could not function! Proteins are chains of amino acids linked together in peptide or polypeptide bonds, responsible for supporting our blood, bone, hair, skin, neural pathways, internal organs, cellular life, nervous system, and numerous other biological functions. Proteins are complex macromolecules that carry out the information maintained in our DNA, keeping us alive, developing, and reproducing. Proteins also regulate and repair our genes, transcription factor proteins go as far as turning genes off and on, like a switch.
Evolution - Gene Mutation
Mutations are permanent alterations to the nucleotide sequence of Genes. Changing the sequences that define proteins, meaning that the result of mutations are different protein makeups. Genetic mutations are either hereditary or somatic, hereditary mutations are passed to the offspring of the organism, diversifying life. And somatic mutations are confined to the organism in which they occur. Mutations can be caused by external, internal, or chance occurrences.
Defining Our Physical Existence
The human body is made up of around 37.5 trillion cells all of which rely on the entire network of cells and messages to function, an entire network either controlled or supported by proteins. And this is not a singular phenomenon, all life we know of requires and relies on amino acids and nucleic acids to make proteins. Animals - from ants to blue whales, utilize the same process. As do plants, from the Wolffia Globose - the smallest flowering plant in the world, to the Rafflesia Arnoldii, a huge and rare plant found in Indonesia.
How Life Progressed to Modern Day
Amino acids and nucleic acids chemical reactions created the first folded proteins which would have the capabilities to create cell-like structures and aid nucleic acid replication.
The intricacies of early cellular life are still being researched and debated. Questions arise about the location of the first chemical reactions that would create life and support replication and proliferation, and if life was RNA-first or Protein-first. But, nevertheless we do have a general understand of the reactions that sparked life.