1 How did primitive protocells assemble and replicate 2 What

1. How did primitive protocells assemble and replicate?

2. What physical mechanisms drove the growth and division of the earliest protocell droplets?

3. Can the fast and accurate non-enzymatic and/or RNA-catalyzed replication of RNA be demonstrated experimentally?

4. How would RNA fitness landscapes constrain the evolution of RNA catalysts (ribozymes)?

5. What kind of sources could have provided energy for the growth and division of protocells?

6. How do phospholipids fit in this hypothesis?

Solution

answer:

1) A primitive protocell is a membrane enclosed collection of molecules that takes up material that assemble and replicates itself. Membranes of early protocells probably consisted of a mix of fatty acids, rather than the phospholipids that make up the bulk of modern cell,The clay serves a dual purpose it encourages the assembly of both nucleotides into RNA and fatty acids into vesicles.

2) A fatty-acid membrane was needed to corral the chemicals of life of protocells, and incubate biological complexity.  protocells might have been liquid droplets—naturally forming, membrane-free containers that concentrate chemicals and thereby foster reactions.

3)A central tenet of the RNA world is that RNA polymerases could replicate themselves. Over the last 20 years, RNA-dependent RNA polymerases have been evolved that can copy RNA sequences longer than themselves. The development of these polymerases required many rounds of selection and amplification. Since amplification would have required a polymerase there appears to be a paradox.

4)RNA fitness landscapes defined by aptamer binding affinities, that constrains the RNA molecules to those that have the binding motive . Fitness Landscapes of Ribozymes and Other RNAs, the relationship between genotype and phenotype can be described by a fitness land scapes.concept can be extended to describe the relationship between phenotype (e.g., biochemical activity) .fitness land scapes are smooth and rugged. Fitness Landscapes of Ribozymes and Other RNAs In the most general sense, the relationship between genotype and phenotype can be described by a fitness landscape, and adaptation is an optimizing walk on this high-dimensional surface.

5)in the Protocell,  growth, division and metabolic activity could be observed according to its inherent properties of duplication  according to its inherent properties of duplication and adaptability and with a source of energy available for this activity, the globule .Thus the enzymes, factors for genetics control, nucleic acids and energy- liberating systems of adenosine phosphatestype may used as source of energy.

6)   Phospholipids are amphipathic.Phospholipids can be asymmetric through the active translocation of a phospholipid type from one leaflet of the membrane , hypothesized that cell membranes are made out of lipids.phosolipids are the pirmary sources of plasma membrane...............................