Results of experiment to grow bacteria in the presence of Penicillin 

The colonies of bacteria appear different colours and textures

In the photo below the cream coloured bacteria in the petri dish with a penicillin disc seem to have been killed around the disk, although they grow well in the rest of the petri dish.

The cream bacteria on the left are killed by the penicillin but the yellow colonies grow right next to the penicillin disc.

The black and white colony is not arrected by the penicillin.

The last two photos show examples of antibiotic resistance.  Remember that penicillin only affects one type of bacteria, by stopping the production of it's peptidoglycan cell wall.