Different DNA

"Most eukaryotic chromosomes include packaging proteins which, aided by chaperone proteins, bind to and condense the DNA molecule to prevent it from becoming an unmanageable tangle."

However there is a phase in cellular mitosis (division) when, before replication, chromosomes need to be unpackaged.

How do they manage to remain a "manageable tangle" during that period?

BTW there is another thing i don't understand in this video that shows a strand already unpackaged being processed by the enzymes helicase/polymerase to create two strands. Where it comes from the "material" added by the polymerase to create the second strand?

Can a packed chromosome perform the same function like transmitting information to ribosomes on how to build protein as an unpacked one? How fragment copies of DNA pass that "scaffolding" (image below)?

According to current theories, human chromosomes' "double stranded helicoidal DNA" range in length from 51 million to 245 million base pairs of atoms. At actual size, an average human cell chromosome totals up to 3 meters long and a few angstroms (10 to minus 10 meters) wide, made of two very long strings (strands) of atoms linked together as pairs. The longest known molecule.

To replicate, each double helix has to unwind and separate in two strands and and each strand of course has to stay in one piece. Each strand then acts as a template for a new strand or its new pair that needs to be packed back together. But at least at a certain moment when it is unpacked, it should be indeed an "unimaginable tangle".

And who or what is doing the job of unpacking/packing, scaffolding, etc..?

If you take a look at the picture below you'll see the 5 levels of winding or packaging of the DNA. At least at three different levels the DNA is packed with different types of "fiber".

http://www.bio.miami.edu/dana/pix/eukchromosome.jpg

Chromosomes are visible under microscope. Here is a video showing the very moment of the separation of the chromosomes during the mitosis (dividing) of one cell.

However no unpacking, unwinding/rewinding etc. of the double helix strands is apparent. They appear to separate like they were in the final stage from the picture above. According to the current theory the video basically shows each chromosome as a clew separating into two without any unwinding.

This video (animation) catches and earlier phase, "condensation" but still no replication. Condensation appears to be the last level of packaging as in the image above.