{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Origin of Cells - consequence of RNA activity Then DNA...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Origin of Cells The appearance of the first cells marked the origin of life on earth. However, before cells could form,  the organic molecules must have united with one another to form more complex molecules called  polymers.  Examples of polymers are polysaccharides and proteins.  In the 1950s, Sidney Fox placed amino acids in primitive earth conditions and showed that amino  acids would unite to form polymers called  proteinoids.  The proteinoids were apparently able to act  as enzymes and catalyze organic reactions.  More recent evidence indicates that RNA molecules have the ability to direct the synthesis of new  RNA molecules as well as DNA molecules. Because DNA provides the genetic code for protein  synthesis, it is conceivable that DNA may have formed in the primitive earth environment as a 
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: consequence of RNA activity. Then DNA activity could have led to protein synthesis. For a cell to come into being, some sort of enclosing membrane is required to hold together the organic materials of the cytoplasm. A generation ago, scientists believed that membranous droplets formed spontaneously. These membranous droplets called protocells were presumed to be the first cell. Modem scientists believe, however, that protocells do not carry any genetic information and lack the internal organization of cells. Thus the protocell theory is not widely accepted. Several groups of scientists are currently investigating the synthesis of polypeptides and short nucleic acids on the surface of clay. The first cells remain a mystery....
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online