What prevents micro evolution from becoming macro evolution

I'm not sure why you think this. There is plenty of pop. gen. and comparative genetic evidence for fixation of deleterious mutations. Certainly the trends for beneficial and deleterious mutations are as you desribe, but in the real world there is plenty of evidence of deleterious mutations accumulating.The real question is, as Slevesque posits, whether such mutations are balanced by compensating beneficial mutations or conversely whether organismal fitness is in an irreversible decline, for which there is no evidence except in some organisms with drastically reduced population sizes.TTFN,WK

When you want to try and frame an opening post about science it would probably be good not to get half of it wrong.Transcription is the process whereby a DNA strand template is used to produce mRNA, when DNA is copied it is called replication. The genetic code also specifically refers to the complementarity of certain codons for certain amino acids. What is copied during replication, and transcribed in transcription, are genetic sequences.Terms like 'transcription' and 'Genetic code' have specific well defined meanings in molecular genetics, couldn't you try and adhere to them?TTFN,WK