Alien, in the sense that the common ancestor with animals was a single celled creature, and our evolution has been diverged for so very very long.
As long as physical laws are consistent, it seems likely that life elsewhere will be proteins, carbohydrates, lipids, and nucleic acids. If a biologist were to assert that any hydrocarbon based life must have to use DNA or RNA to communicate protein sequence information, i'd accept it as quite plausible. The relationship between the nucleic acid code and amino acids is determined by the physical shape of the molecules: what is interesting is that earth life doesn't make use of all the amino acids. New proteins could be part of the molecular machinery of other life.
General cell development seems pretty much chemistry and not something earth specific.
So, there are two classes of cells, those where there's just an inside the cell and an outside, and those where there are smaller units within the cell separated by a membrane. It's those smaller units that are likely to be different than ours based on what the abundant forms of energy are. And that is part of the fundamental difference between plants and animals: plants have one of these units that process energy, and we animals don't. Plants colonized the land long before animals: if animals hadn't come out to fill the niche available to creatures that moved, would plants have developed that facility? Watching the parasitic dodder in time lapse as it hunts out its prey plant is ... really creepy.
I remember how nellorat opined that timelapse was in general creepy. As i become more aware of the biology of plants, i find the timelapse images alien. Plants aren't just some background stage dressing. They really do have behavior in perceptual zones that are different than ours....
Energy is mostly up around the house, which is good.
This is also posted at http://elainegrey.dreamwidth.org/533179.html .