Those special segments of DNA are known as genes. So a gene is a special segment of the DNA, the sequence of nucleotides that codes for a protein that is used to help us express those traits and those characteristics that are found on that individual, on that organism. Now, along the chromosome, so this is a single chromosome. Along the chromosome, we can have thousands of different types of genes. And in this particular diagram, we have only six genes. So we have a red gene, we have a green gene, we have our blue gene, the light green gene, the dark purple and the light purple gene.