It would be most likely that their children has blood type AB.
The oldest type of bacteria is over 3 million years old I think. It comes from the cyanobacteria family! The bacteria is a type of algae! Discovered by Gregorio V. in the Late 1900's.
Here is the correct flow chart: GENE > DNA > CHROMOSOMES > NUCLEUS.
The cell nucleus contain chromosomes which are made from long DNA molecules. A gene is a short section of a DNA which codes for a specific protein.