Every living thing is made of tiny units known as cells. Your dog, your teacher, the grass and trees outside, the bacteria that make you sick, and even you, are all made of tiny cells that are too small to see without a microscope. We don't think about it but these cells are always growing, dying, and dividing as they go about their job of being...us. Cells are extremely complicated but the simple representation below suffices for most diagrams. Note that many important pieces of the cell are left out, such as the Ribosome which makes proteins, and the Mitochondria which generates energy from food.
While cells have been around and understood for quite a while, it was not until the 1950s that we began to understand how cells managed their complicated roles. At that time, Francis Crick articulated something he referred to as the "Central Dogma of Biology." This dogma was that the genetic code (DNA) coded for a message carrier (mRNA) that was used to produce proteins, the final products of the genes. While the interaction between DNA, RNA, and Protein has since proven to be slightly more complicated, the fact that DNA creates RNA which create Proteins remains the backbone of life.
DNA functions as the basic code of the body. Everything contained within your body or the body of any other living organism is, in some way, encoded in the DNA. DNA acts as the blueprint for all the parts of the cell and is unique to each organism (except for clones or identical twins). It is composed of a twisted double helix, is found in the center of cells during normal cell processes, and creates structures known as chromosomes.
There are many types of RNA that serve a number of highly specialized purposes in the body. It is very similar to DNA in structure except it exists as a single, unstable strand. The primary use of RNA in the cell is as a messanger for DNA code. Because the DNA is contained in the central nucleus, it cannot move and requires mRNA (messenger RNA) to transfer the DNA code to the part of the cell where proteins are made.
Proteins are the functional blocks of the cell. If DNA is the information blueprint, and RNA is the paper used to transfer it from place to place, then Proteins are the copiers, readers, writers, builders, and the end product. Put simply, proteins do everything in the cell. They provide structure, perform all the tasks within the cell, and act as the products of the cell and the method for the cell to communicate. Proteins are the end product of every bit of DNA code, and the real reason why DNA is important. DNA that does not affect proteins in the cell does not have an effect on the cell, and disrupting the process of changing from DNA code to Protein product is equivalent to removing a chunk of the DNA in the first place. Dirsupting the process of moving from DNA to Protein is, in fact, the basis of a biotechnology that has revolutionized the study of cells, and of cancer, RNA Interference.