How is a DNA molecule split as it is copied?

Answer 1

The process of copying DNA (called replication) begins at what is called the origin of replication. This is simply a point on the chromosome where DNA polymerase knows to start replication. In most prokaryotes, there is only one origin of replication. In eukaryotes, there are usually multiple origins on each chromosome.

Answer 2

By splitting DNA down the middle, you have two complimentary strands. Adenine (A) always pairs with Thymine (T), and Guanine (G), with Cytosine (C). For example, A-T, G-C, would split between the bases. Then complimentary bases are added to the new strands, followed by phosphate-sugar backbone.

Answer 3

It locally unzips (much like a zipper) and each strand is duplicated, forming 2 identical molecules.

Each of these could potentially locally unzip and be duplicated again while the original molecule is still being copied the first time (however this only happens in a few DNA based viruses that replicate using their own enzyme systems instead of depending on the host's, never in cellular organisms).

Answer 4

the DNA is composed of two strands. in order to replicate the strand separate. once separated the other halves get filled in by nitrogenous bases that are floating around in the environment.