Answer: DNA is a double stranded molecule. When DNA is copied the two strand of DNA (old strands) separate and new nucleotides match up with the two separated strands.
This process creates two identical double stranded DNA molecules are formed. Each DNA molecule contains one strand of the original DNA molecule and one newly synthesized (made) strand.
Explanation: https://youtu.be/Gxoyr8JKc4w
Hope this helps :D
