AP BIOLOGY

Detailed explanation-1: -The RNA world hypothesis suggests that life on Earth began with a simple RNA molecule that could copy itself. The RNA world hypothesis suggests that life on Earth began with a simple RNA molecule that could copy itself without help from other molecules. DNA, RNA, and proteins are central to life on Earth.

Detailed explanation-2: -The hypothesis that RNA preceded DNA and proteins in evolution. In the earliest cells, pre-RNA molecules would have had combined genetic, structural, and catalytic functions and these functions would have gradually been replaced by RNA.

Detailed explanation-3: -In an RNA world, the standard theory says, life could have existed as complex proto-RNA strands that were able to both copy themselves and compete with other strands. Later, these ‘RNA enzymes’ could have evolved the ability to build proteins and ultimately to transfer their genetic information into more-stable DNA.

Detailed explanation-4: -One ancient view of the origin of life, from Aristotle until the 19th century, is of spontaneous generation. This theory held that “lower” animals were generated by decaying organic substances, and that life arose by chance.

Detailed explanation-5: -RNA can direct the creation of proteins and perform other essential functions of life that DNA can’t do. RNA’s versatility is one reason that scientists think this polymer came first, with DNA evolving later as a better way to store genetic information for the long haul.