The amino acids in a protein determine how it folds into a three-dimensional shape; this structure is, in turn, responsible for the proteins function. Proteins carry out almost all the functions needed for cells to live. A change to the DNA in a gene can change a proteins amino acids, changing its shape and function: this can have a dramatic effect in the cell and on the organism as a whole. Major metabolic reactions by which the cell obtains and stores energy is in the form of ATP. This metabolic energy is then used to accomplish various tasks, including the synthesis of macromolecules and other cell constituents like carbohydrates, lipids, proteins, and nucleic acids.
Researchers believe that RNA is a unique molecule and the earth is home to RNA-based organisms, which could find food, grow and reproduce and gradually switch to double-stranded DNA. Proteins cannot be made by RNA-based organisms, so they could live where main ingredients like sulphur, required for protein synthesis is absent. By extraction of DNA, the genome pattern of various species can be established. Scientists are rewriting the genetic code and using engineered bacteria making new proteins with new amino acids. Designing new proteins, looking for signs in metabolic activity in varnishes, scientists are now looking for alternate forms of life. The fact that Deinococcus radiodurans withstood 1000 times the amount of radiation to kill humans, suggests that there might be a life which we do not