Does MMR lump ranked and normals together?

In ranked I am JG main. However, im going to start playing normals to learn ADC and Mid (more carry potential). Am I better off making a new account to do this so I dont get dumpstered on, or does the MMR adjust rather quickly. I just dont want my teammates to flame me as I am going to lose really bad more games than usual. And will this MMR affect my ranked placement? I have only one account right now which I have had since season 5. I have all the champs so was avoiding having to restart a new one to do this. Just wondering what is best, thank you.