Cell simply divides in half but before it does it must duplicate all its essential structures, primarily the chromosome. Can't just give half the genes to the new cell since it only has 1 copy of each. Duplication of DNA called replication or the bacterial replicon . Often called the theta replicon. Each daughter contains a parent strand and a newly synthesized strand.
Origin of replication is always a palindrome.
This process creates 2 replication forks that gradually open up the 2 strands using helicase to unzip the H bonds. New nucleotides that are floating in the cytoplasm after being made through anabolism, bind to the complementary base as it opens up, gradually building 4 strands from 2. Replication happens in both directions at once since 2 replication forks, but remember that new bases can ONLY be added in the 5' to 3' direction. Continuous replication happens on the leading strand very quickly but slower on the lagging strand . Bases are laid down 5' to 3' on both leading and lagging strands but on the lagging strand growth is discontinuous.