Lactate dehydrogenase (LDH or LD) is an enzyme found in nearly all living cells. LDH catalyzes the conversion of lactate to pyruvate and back, as it converts NAD+ to NADH and back. This is how it allows glycolysis to continue.
The cells are identical because the DNA is copied during the S phase before cell division and then each resulting cell gets a matching copy of the chromosomes.
