Describe the emergence of biological organisms in all their complexity from basi

Question

Describe the emergence of biological organisms in all their complexity from basic material origins to the world we see today. In your description, be careful not to use skyhooks and base your descriptions on evidence, not just proposition.This means that you should be highlighting how science has come to understand what you’re saying rather than relying solely on philosophy. Remember to be careful in your logic as we spoke about in class. It is not science to search for examples, but to search for evidence against. Single examples can be support but are not what we ‘search for’. Include at least the following elements in your description:

1. Early molecules and self-replication

2. Black smoker vents

3. Protein functional changes and the link to genetic evolution

4. Evolution from the perspective of DNA.

Explanation / Answer

In the first stage of evolution, molecules in the primitive environment formed simple organic substances, such as amino acids. Further evolution occured in four stages. First, abiotic synthesis and accumulation of monomers, or small organic molecules, that are the building blocks for more complex molecules. Second, joining of monomers into polymers (proteins and nucleic acids). Third, formation of protobionts, droplets which formed from aggregates of abiotically produced molecules and which differed chemically from their surroundings. Fourth, origin of heredity during or before appearance.

The discovery that RNA molecules that can act as catalysts in their own formation suggests that RNA or a similar molecule may have been the first gene and the first catalysr. The concentration of a self replicating RNA molecule would increase exponentially . In the competetion for nucleotides, the most efficient of the self replicating sequences would win and less efficient replicators would fade from the population.

According to the RNA world hypothesis, the division of function between DNA and proteins occured. New variants of self replicating RNA molecules developed, with the additional ability to catalyse the condensation of amino acids into peptides. The peptides thus formed would reinforce the self replicating ability of RNAs.

Sometime after the evolution of the primitive protein synthesising system, DNA molecules with sequences complementary to the self replicating RNA molecules took over the function of conserving the genetic information and RNA molecules evolved to play roles in protein synthesis.

Proteins proved to be versatile catalysts and over time took over the function. Lipid like compounds in the primordial soup formed relatively impermeable layers around self replicating collections of molecules. The cocentrations of proteins and nucleic acids with these lipid interactions favoured the molecular interactions required in self replication.

Related Questions

Navigate

• Browse (All)
• Browse D
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.