All of life on earth operates using mostly the same biochemistry. While there are countless differences and exceptions (eg. different codons, different genome architecture, metabolic and gene product differences), they are vastly outweighed by the vast magnitude of commonality. This is mostly observable at the small scale (nucleic acid, protein, lipid chemistries) but also somewhat true at a larger scale (certain transport processes, etc).
Bacteria have an incredible amount of biochemistry in common with us. And so do all other living things. Bacteria will of course be radically different when we contrast ourselves to other eukaryotes, but we can still see our biochemistry in them.
We all evolved from the same lineage, so all of the "core architectural" decisions were made long ago--before prokaryotes even came into being. The earliest choices made in exploring the chemical-physical fitness landscape turned out to have the greatest impact; all of our biology is expressed in terms of the primitives that were first established. For example, the universal adoption of the amino acid L-isomers. It's a seemingly arbitrary choice of little importance, but once that choice was made, earth biology forever had to live with it.
If there were different paths taken early on, metabolism would be different, polymerization would be different--cellular replication itself might also be different (one can only imagine). I imagine there would be cells. At higher levels, the choice of "building blocks" has an impact on bioinorganic chemistries (think heme groups). How you chelate depends on structure.
I assume that the heme group chemistry only evolved because of a highly oxygenated environment that life could exploit for energy production. Had our aqueous environment (and later atmosphere) been of a different composition, oxygen may not have played the same role.
Further tangent: certain elements are extremely important. Organic (carbon) chemistry is incredible due to the valence. Evolving on a world without oxygen might really suck, because oxygen chemistry is just so perfect for redox. And what of all the other important chemistries? Do they have a bioavailable source?
Anyhow, it's suffice to say that any change in early evolutionary choices would have far-reaching impact on the essential reactions (energetics, thermo, kinetics, dynamics...) and might yield results that are altogether alien to us from an Earth biology standpoint. Once you have your building blocks, you can't exactly backtrack.
All of life on earth operates using mostly the same biochemistry. While there are countless differences and exceptions (eg. different codons, different genome architecture, metabolic and gene product differences), they are vastly outweighed by the vast magnitude of commonality. This is mostly observable at the small scale (nucleic acid, protein, lipid chemistries) but also somewhat true at a larger scale (certain transport processes, etc).
Bacteria have an incredible amount of biochemistry in common with us. And so do all other living things. Bacteria will of course be radically different when we contrast ourselves to other eukaryotes, but we can still see our biochemistry in them.
We all evolved from the same lineage, so all of the "core architectural" decisions were made long ago--before prokaryotes even came into being. The earliest choices made in exploring the chemical-physical fitness landscape turned out to have the greatest impact; all of our biology is expressed in terms of the primitives that were first established. For example, the universal adoption of the amino acid L-isomers. It's a seemingly arbitrary choice of little importance, but once that choice was made, earth biology forever had to live with it.
If there were different paths taken early on, metabolism would be different, polymerization would be different--cellular replication itself might also be different (one can only imagine). I imagine there would be cells. At higher levels, the choice of "building blocks" has an impact on bioinorganic chemistries (think heme groups). How you chelate depends on structure.
I assume that the heme group chemistry only evolved because of a highly oxygenated environment that life could exploit for energy production. Had our aqueous environment (and later atmosphere) been of a different composition, oxygen may not have played the same role.
Further tangent: certain elements are extremely important. Organic (carbon) chemistry is incredible due to the valence. Evolving on a world without oxygen might really suck, because oxygen chemistry is just so perfect for redox. And what of all the other important chemistries? Do they have a bioavailable source?
Anyhow, it's suffice to say that any change in early evolutionary choices would have far-reaching impact on the essential reactions (energetics, thermo, kinetics, dynamics...) and might yield results that are altogether alien to us from an Earth biology standpoint. Once you have your building blocks, you can't exactly backtrack.