Forms of DNA

What does DNA stand for? Deoxyribonucleic acid

Why is DNA important? DNA contains the genetic instructions used in the development and functioning of all known living organisms. The main role of DNA molecule is the long-term storage of information. –DNA is often compared to a set of blueprints, like a recipe or a code, since it contains the instructions needed

Chromatin A tangled mass of genetic material made up of a combination of DNA and proteins. It has no organization. Looks like a messy ball of yarn. When DNA is in this form, all you can see is a black mass in the nucleus when looking through a microscope.

Chromatid DNA in a very organized coiled form. When DNA is in the form of chromatids (sometimes called chromosomes) they can be seen under a microscope and rod like structures.

Chromosomes Sometimes scientists use the term “chromosomes” to describe chromatids. Other times the word is used to describe DNA after replication (copying) when each chromatid had a copy of itself (and has attached itself to that copy by a centromere)

Why these different forms are important: DNA cannot perform all of its functions with just one form. Chromatin is important because this is the form in which it carries out its job as instructions. Instructions cannot be read when it is in chromatid form. Chromatid form, however, is organized enough to make dividing it up evenly easy, and allows for less mistakes.

Cell under electron microscope: Sister Chromosomes Exchange: Humany chromosome and karyotype: knowledge/cell%20division/human%20chromosomes.gif