AP BIOLOGY

Detailed explanation-1: -Evidence that RNA arose before DNA in evolution can be found in the chemical differences between them.

Detailed explanation-2: -We are reasonably sure now that DNA and DNA replication mechanisms appeared late in early life history, and that DNA originated from RNA in an RNA/protein world.

Detailed explanation-3: -RNA is thought to have preceded DNA, because of their ordering in the biosynthetic pathways. The deoxyribonucleotides used to make DNA are made from ribonucleotides, the building blocks of RNA, by removing the 2’-hydroxyl group. As a consequence a cell must have the ability to make RNA before it can make DNA.

Detailed explanation-4: -The discovery of RNA began with the discovery of nucleic acids by Friedrich Miescher in 1868 who called the material ‘nuclein’ since it was found in the nucleus.

Detailed explanation-5: -According to the RNA world theory, the first RNAs were made using free-floating nucleotides that emerged in a primordial soup of molecules. They bonded together to make strands of RNA that weren’t very stable and degraded quickly.