system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If your body is constantly replacing skin cells with new ones, why do scars last a long time?

From what I've learned new cells "know" what to be based on your DNA (though I could be wrong on this one). Since injury does not change your DNA, it should not affect the color or arrangement of new cells.
gpt
Your outermost region of the skin, the epidermis, is made of a number of sublayers, and _new_ skin cells are only made in the bottom sublayer. These new cells divide and move up the skin layers until it reaches the surface and sloughs off.

A shallow scratch damages the top layers of the cells, and the wound heals when new cells move up to replace them. A wound deep enough to damage the basal layer will hurt those dividing cells. Without a source of new cells, your body compensates with a make-shift network of proteins to connect the tissue - that's why a scar looks different from surrounding cells.