There are several ways to know that, but sometimes can be very difficult to know the answer to that question.

Firstly, to know the function of a given gene, scientists try to delete that gene and see what effects causes in the cell which possessed that gene. For example, if the depletion of the gene makes the cell unable to divide, that gene can be involved in the mitosis process. A huge amount of information about genes has been obtained from the studying mutants lacking genes./

Secondly, some genes can have a similar sequence to other genes with a known function. Using bioinformatics is easy to compare different genes and sometimes it is possible to predict the function of a gene thanks to its homologies to other gene.

That question is impossible to answer with certainty because the question is that maybe we have to wait several decades or centuries to see that. The closest scientific achievement to the creation of life was the synthesis of the whole genome of the little bacteria Mycoplasma genitalium by the American scientist Craig Venter in 2010. You can read more information about it clicking the next web address. Mycoplasma laboratorium

Synthetic biology is a tool that can be used to solve many problems. However, it is still a very young discipline which is given its first steps that has a long road to cover.

The climate change is caused mainly because of the CO2 emission to the atmosphere by the human being. If we want to preserve our planet we have to diminish these emissions that are responsible of the progressive warming which is affecting so many different animals and plants and changing the climate patterns. One way we could do that is using renewable energies and biofuels and avoiding the use of oils. Once time that Synthetic biology becomes a true engineering and passes its childhood, can be a useful tool to produce cells dedicated to the production of several types of biofuels, which could reduce highly the CO2 emissions and contribute that way to the war against climate warming.