In laboratories around the world there is an intense desire to sequence more genomes.

  • those of a wide variety of organisms to aid in establishing evolutionary relationships;
  • those of pooled populations of microorganisms in, for examples, sea water, soil, the large intestine;
  • other humans to look for
    • genes that predispose to disease;
    • genetic patterns in various ethnic groups.

All of the sequenced genomes listed in Genome Sizes were determined using the

Harlequin Chromosomes

Incredible though it may seem, each single human chromosome that you observe under 440x magnification of your laboratory microscope contains a single molecule of DNA. For some of our chromosomes, this molecule — if stretched out — would extend 5 cm (2 inches)!

This image demonstrates that

  • each chromosome contains but a single molecule of DNA and that
  • the replication of a chromosome is semi-conservative (just as is the replication of a single DNA