Mageth

If bacteria or any actual life was found on another planet I'm assuming we would expect this life to be completely different than anything found on earth.

Well, if bacteria were found on another planet, you should already see that it would share many similarities to bacteria on earth (single-cell, organized with a cell wall and contents, cell wall porous to allow intake and output, reproductive capability, energy processing capability, etc.). From there, to achieve more complexity, the easiest route is to multicellular systems. Similar needs to multicellular forms here on earth would drive the evolution of those organisms, resulting in more similarities.

All one has to do is look at convergent evolution here on earth to see examples of what ps418 and AdamWho refer to - life seems to tend towards optimal solutions to some problems. For example, there are only so many ways to move about in water, on land and in the air. Most of those ways have been tried by life at one time or another here on earth. The same is true for other functions - reproduction, food consumption and waste disposal, circulation, etc. To efficiently circulate fluid such as blood requires some kind of pump, so any complex organism with a circulatory system would no doubt have a functional equivalent to a heart. Likewise, any sentient organisms we encounter will no doubt have the functional equivalent to a brain.

Bottom line, I think any life we encounter will be remarkable not only for differences from life here on earth but also for similarities.

Also note the remarkable variety of life forms found here on earth. Any life we encounter will more than likely be comparable to one or more of those life forms.