system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When you drop an apple and it bruises, what's happening?
gpt
The once rigid cells are ruptured by the force of impact, resulting in a mushy soft spot. As for the discoloration, the impact compromises the integrity of the skin and allows oxygen into the apple. The oxygen also causes more cellular degradation and eventually rot.