13.2 study

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RNA molecules have a base sequence that can carry info, and some of the larger ones have catalytic properties. They can accelerate the rates of certain reactions much as protein based enzymes do in modern cells.

As the RNA world evolved, it was discovered that no set of conditions would favor the production and maintenance of both the ribose sugar and the nitrogen base components needed for assembling the nucleotide monomers.

The correct bonding of amino acids to tRNAs requires the specific catalytic activity of tRNA synthetases (which is a protein enzyme that binds a specific class of transfer RNA molecules and binds a specific kind of amino acid to them.)

Evolutions final challenge spatial ordering of biological activity:

As the RNA world progressed, new difficulties emerged. It was discovered that no set of conditions would favor the production and maintenance of both the ribose sugar and the nitrogen base componenets needed for assembling the nucleotide monomers. But you cannot generate RN polymer without constituent monomers. In cells, such monomers are made in highly coordinate, enzyme driven metabolic pathways.

RNA molecule production is difficult to model in the early oceans; a variety of conditions are needed to generate the separate parts of the monomeric units.

RNA molecules aren't catalytic until they reach 100 nucleotides in length, a size that may have been geochemically unachievable.

No model exists for how RNA molecules could begin to code for simple protein molecules, yet protein catalysis is critical to the survival of the modern cell.

Dr, Cricks regarding the origin of life? He didn't have an answer. Instead, he argued that life seeded on this planet as a small variety of cellular forms apparently superior to us.

In order for to side step difficulties of inherent in showing how cellular life evolved , Crick and Orgel postulated that directed panspermia had occurred-primitive but functional cells were seeded on this planet by superior beings capable of such behavior.

The hypothesis that random generation assembly of biological molecules could produce a functioning cell is simplistic; it does not account for the information required to structure the cell.

The hypothesis lacks: select appropriate monomers from an ultra complex organic slime, 2. and drive and protect polymer formation without stimultaneous polymer degradation and 3. give biological meaning to random polymers generated.