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.
Animal belonging to urochordata show notochord only in posterior part of body i.e. tail region hence named. In urochordata notochord is seen only in larval stage and lost in adult stage. Body is segmented. Body is unsegmented covered with tunic or test. Body is fish like, free swimming animal.