Change one Letter

sit = pit....................

pit = Pot......

pot = pat................

pat = hat.....

hat = mat..................

Mat = Pat.......

Pat = cat,,,,,,,,,,,,,,,,,,,,,

cat = Tar......

tar ... bar

bar = are.......................

are ... tar

tar = Rap...........

rap ... ape

ape = pen..............

pen = Nap.......