Combining shape paths?

Im absolutely baffled by what should be the simplest task. I've made this simple shape via a line + an ellipse in the same shape layer. I need to be able to treat the shape as one object so that I can animate the rounded tip of the shape (the position of the ellipse) and the line will stay attached to it. The opposite end of the line needs to stay put as the ellipse moves around. I also need the line to contract/expand as the ellipse moves. Thanks!