What was the history of life on earth recorded in?

If the coding part of an mrna molecule is 1800 nucleotides (bases) in length, this molecule will contain codons and code for a polypeptide that is amino acids long.

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?

The earth's oceans are made up of chlorine, and trace elements. a) carbon, oxygen b) oxygen, silicon c) hydrogen, oxygen d) nitrogen, oxygen