deoxyribonucleic acid, desoxyribonucleic acid, DNA(noun) (biochemistry) a long linear polymer found in the nucleus of a cell and formed from nucleotides and shaped like a double helix; associated with the transmission of genetic information.
But even adults don't often know what a notochord is. A notochord is a primitive beginning to the backbone. It appears in embryos as a small flexible rod made from cells from the mesoderm, which is one of the three layers of cells of embryos. Notochords are only found in the phylum chordata, a group of animals that includes humans.
Chordata-Vertebrates, Tunicates, Lancelets. At some point, all of the organisms in this phylum have a structure called a notochord. A notochord is a flexible rod-like cord of cells that provides the main support for the organism's body during its embryonic stage.n some primitive species, the slits are used to filter food out of the water. In other species, like fish, the pharyngeal slits have gills. In other species, like mammals, the pharyngeal slits are only present during the embryonic stage. Chordates also have a dorsal nerve cord that runs down the length of the organism.