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Name: Hans
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Question:
Is it sure that the most important information of living cells is stored in the DNA? DNA seems to be nothing more than an inventory of useful proteins and a tool to create those proteins. Could it be that more important operational know how of how these proteins interact to build a living organism is actually located in the rest of the cell? So that the rest of the cell is the most important inheritance, whereas DNA merely takes care of the genetic variation?



Replies:
DNA is the entire library of protein information for an organism. All seven types of protein. It is true that in developmental stages of an organism that the presence and absences of certain proteins and other chemicals generated by proteins will influence what the DNA in a "particular" cell will express. Hence, you can start out with one cell and end up with a complex organism. You may have heard some of this information with the cloning activities that have been going on lately. All the inheritance comes from the DNA, but what parts of the DNA expression may be dictated by the cells special characteristics developed upon specializing. In that way the liver cells will only do "liver" things and the kidney cells will only do "kidney" things, BUT they use the same DNA information to operate, just a different portion of the same DNA that pertains to their particular "job". If you can convince a cell that it does not have a special job anymore, then you can develop the entire organism from this cell with the right signals; this is what cloning techniques have done!

Steve Sample


If the genetic content of a cell were more than DNA, it should be present in the germ cells to be passed on to future generations. And you are right: DNA itself is not enough. The way the DNA is folded and kept together by proteins adds to the information carried on the DNA. So although the DNA (in some viruses it is RNA) is the carrier of genetic information, this information can only be correctly interpreted ('exrpessed') if the DNA is covered and held together by the correct proteins. This complete structure is called the chromosomes, and these, as is generally believed, are sufficient for all genetic information. Modern technology in which 'empty' germ cells are refilled with chromosomes from foreign donor germ cells confirm this theory.

Dr. Wassenaar



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