Rather than using old school 3" or 4" Petri dishes, most molecular biology is now done in miniature culture wll plates, with 96 little wells (each holding maybe 20 microliters of cells or reagents) in the form factor of about a 3x5 card. With 96 different tubes, you can run a whole experiment on a single plate, with controls and replicates. Lots of infrastructure for "reading" the plates (taking measurements of reaction, incubating at set temperture, etc.) But that raises the issue of keeping track of what went in which of the 96 wells...