G Em Am D

This is the bass line through out the entire song:
     G           Em       Am     D
|------------------------------------|
|----2-5-2-5-2-5---------------7-----|
|----------------2------2-0------5---|
|---------------------3--------------|

On occasion the bass walks down over the D chord like so:
( listen to the song to hear it )
     G           Em       Am     D
|----------------------------------------|
|----2-5-2-5-2-5---------------7---------|
|----------------2------2-0------55-8-7-5|
|---------------------3------------------|