gene theory
The gene theory is the idea that the characteristics of living organisms are controlled by genes, which are passed from parents to their offspring. A gene is a segment of DNA that has the instructions to encode a protein. Genes are located on larger structures, called chromosomes , that are found inside every cell. Chromosomes, in turn, contain large molecules known as DNA deoxyribonucleic acid . Molecules of DNA are encoded with instructions that tell cells what to do. To see how this happens, click on the animation titled Journey into DNA at the following link: http://www. pbs. org/wgbh/nova/genome/dna. html .