In nature. All living organisms, beginning with the very, very small ones, such as individual bacterial cells and ending with a very large complex ones such as human bodies that consist of trillions and trillions of individual cells. All living cells contain DNA as the carrier of genetic information. And what that means is we have the DNA molecule that that is used to store the genetic information that is basically transcribed into the RNA molecule and then it's the RNA molecule that is ultimately used to synthesize the many different types of proteins that are used by that cell and needed by that cell to survive. Now, in human cells, we have linear molecules of DNA and what that means is we have a beginning and we have an end. But in other organisms, for example, bacterial cells, they have circular DNA molecules.