LAD DNA and ANA: The Central Dogra ol Biology 99 DNA replicmige in considered semiconservative because half of the oreinal strand bs conserved and stays together.As yon can see in the image abore, one original blue stand remains intact in each of the final nolecules. and a dew yellow strand gets built and anached to it via basc pauring. Pracrice DNA replication below by usine the base painng nole- DNA tequence: ATCCGTAAGGTCA Makching strand: The image bekrw is nor in the comect order. Recond the nombers an the contet onder Mutations Sometimes, mistakes happea, even during D.AA replication. A mutation is when the genelic code changes. There are varioes ways this can happen isee image below, does not inclode all possibie mutarions). Most mutations are noither bad nor beneficial, cither becawse they happen in the junk DNA," do noc cause a change in armino acid, ar produce changes they can't really be valueal as good or bad. Several matations are harmful, and a small few are beneficial (such as oertain people being immuac io HIV because their cells lack the receptors for the virus). There are many haman genetic diseaves, sach as sickle oell anemia, hemophitha, and many mwore. About 3,000 genetic disorders have been identified so far..