Forms of DNA

1. Forms of DNA

2. What does DNA stand for? • Deoxyribonucleic acid

3. 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

4. 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.

6. 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.

8. 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)

10. 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.

11. Cell under electron microscope: http://synapses.clm.utexas.edu/atlas/1_3_5.gif Sister Chromosomes Exchange: http://chromosometesting.com/images/samples/sister.jpg Humany chromosome and karyotype: http://library.thinkquest.org/C0123260/basic%20knowledge/images/basic%20knowledge/cell%20division/human%20chromosomes.gif