Question

EVOLUTION AND MOLECULES OF THE CELL

• What is the proposed pathway for the evolution of cells, and how is it explained by the

  endosymbiont theory?

• What are the major macromolecules of the cell?

• What are the basic characteristics of polysaccharides, lipids, nucleic acids and proteins and how

  do these characteristics relate to the function of these macromolecules within the cell?

• How do the side chains of amino acids in proteins influence protein folding and its ultimate

  shape?

Answer 1

Endosymbionts are the cells which lives inside the host cell.Earlier it was suggested that there were three kinds of prokaryotic cell.One that used to conserve energy by doing aerobic respiration and other one that is capable of doing photosynthesis and another one that cannot perform either of the process.

This theory describe that how easily and with mutual benefit an ingested bacteria live inside the large host cell.Thus,mitochondria and chloroplast cannot live outside the cell.Also the theory proposed that the aerobic bacteria inh=jected by a anaerobic bacteria and they both have a mutual beneficial relationship,as aerobic bacteria can handle the oxygen for anaerobic bacteria.And the food would be ingested by the aerobic bacteria in order to protect the aerobic.

This would lead to a formation of cell which is double membrane bound with the inner lipid bilayer of bacterial cell membrane and the outer lipid bilayer must have come from the cell that engulfed it.

Macromolecules are formed by joining many low-molecular weight precursors like amino acid,sugars and nucleotides.And the macromolecules are proteins,polysachharide,lipids and the nucleic acids.These are the molecules which make the maximum of carbon content of the typical cell.

DNA and RNA are the polymer of nucleotides.It has a 5 carbon sugar,a nitrogenous base and a phosphate group.Whereas the polysachharides are the storage and structural macromolecules,they function as the stored form of carbohydrate.Lipids are the one composed of hydrocarbon and are insoluble in water.All the membranes are formed by the aggregation of lipds.

Proteins are the building block of the body.They are the key enzymes and the hormones of the body which require to run the life supporting activities.Protein folding is the physical process in which the amino acid chains gets folded into the three dimentional structure from an unfolded polypeptide.This folding starts during the translation itself.Folding produce the active protein functionally and structurally.The hydrophobic force is the one that drives the protein folding.And this force is exerted by the side chain of amino acids.