I want to say individuals more so than entire populations. That being said it's because the entire populations of living things are able to evolve and move forward through slow evolution.
You have transcription in which DNA is transcribed into mRNA , then there is Translation in which mRNA is translated into proteins, in other words mRNA translated into amino acids that are going to be bonded together to become a protein
You could say variation in offspring (so cloning things they basically just multiple the exact same thing but with reproduction, whatever is made differs a little bit or a lot from its "parents"
Protease is used to digest proteins
