Just as we chart the world around us, we can map human chromosomes. The features of chromosomes can include protein-coding genes, ancient molecular parasites known as transposons, or stretches of repeat sequences. In this section, take a guided tour of less than 1% of your genetic material to see new and unusual views of your chromosomal landscape. (DNAi location: Genome > Tour > Flyover > Chromosome introduction and globin cluster)

We will now take a tour of about 650,000 nucleotides from the tip of the short arm of human Chromosome 11. This is equal to about half of one percent of the entire chromosome and about 1/5,000th of the human genome. From a distance we can discern 28 genes, denoted by red and yellow blocks. The red "exons" carry the DNA code for protein, while the yellow "introns" are noncoding. Also prominent are more than 500 transposons, or jumping genes, denoted by blue and purple blocks. If we zoom in, we can take a closer look at the structure of this chromosome region. We first encounter a cluster of five small genes, averaging about 1,500 nucleotides in length. These encode components of hemoglobin, the oxygen carrying molecule of the blood. Beta globin is a common component of adult blood, and a mutation to a single nucleotide in this gene is responsible for sickle cell anemia. Delta globin, a minor component of adult blood, is followed by a nonfunctional copy of beta globin, termed a pseudogene. Gamma and epsilon globins are expressed in the embryo and fetus.

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