See base pair. A cellular organelle in plants and animals that contains the chromosomes which in turn are composed of DNA plus protein. A gene gun is used to propel the metal particles. An amazingly sensitive technique that allows the specific amplification of extremely small amounts of particular DNA fragments using DNA polymerase and specific primers. A small circular piece of DNA in bacteria that resembles the bacterial circular chromosome, but is dispensable.
Some bacterial strains contain many plasmids and some contain none.
Plasmids are often used in genetic engineering as cloning vectors. Any enzyme that adds subunits to chains of macromolecules. Example is DNA polymerase. A segment of DNA near the beginning of a gene that controls if and when the gene is actually expressed. Promoters can be specific for certain tissues such as roots, seeds, etc.