How DNA is Packaged (Advanced)

In this animation we'll see the remarkable way our DNA is tightly packed up to fit into the nucleus of every cell. The process starts with assembly of a nucleosome which is formed when eight separate histone proteins sub units attach to the DNA molecule. The combined tight loop of DNA and protein is the nucleosome. Multiple nucleosomes are coiled together and these then stack on top of each other. The end result is a fiber of packed nucleosomes known as a chromatin. This fiber, which at this point is condensed to a thickness of thirty nanometers, is then looped and further packaged using other proteins which are not shown here. This remarkable multiple folding allows six feet of DNA to fit into the nucleus of each cell in our body. An object so small that ten thousand nuclei could fit on the tip of a needle. The end result is that the DNA is tightly packed into the familiar structures we can see through a microscope, chromosomes. It is important to realize that chromosomes are not always present. They form only when cells are dividing. At other times as we can see here at the end of cell division, our DNA becomes less highly organized.

Channel: DNA Learning Center

Views: 1,440,512

Keywords: cell division mitosis, chromosome, building blocks, nucleus, molecule, dna, proteins, labels, animation

Id: gbSIBhFwQ4s

Length: 1min 43sec (103 seconds)

Published: Mon Mar 22 2010