One of the incredibly fascinating features of DNA is that the bases have extreme selectivity when bonding to one another. Adenine will only form a hydrogen bond with thymine and guanine will only form a hydrogen bond with cytosine, each forming a 1:1 ratio. It is partially because of this (known as Chargaff's rule) that Watson and Crick were able to elucidate the structure of DNA. Although there is much more that can be said on this topic, I won't try to explain anything else. Mainly because I don't fully understand it so there's no way I'm going to be able to explain it to others.
Answers to yesterdays questions: transcription is the processes of copying DNA into single stranded mRNA. Translation is the processing of that mRNA into a polypeptide. A polypeptide is a sequence of amino acids, but a protein is a polypeptide with function.
Do you know what percentage of your genome is different than everyone else's?