Ausaf Ahmad aquraish at uclink.berkeley.edu
Mon Mar 21 01:30:21 EST 1994

In article <2mj7n6$9ji at eis.calstate.edu>, dlevins at eis.calstate.edu (David
Levinson) wrote:

> --
>  Hi,
>    I have a few questions that I need answers to URGENTLY regarding DNA. 
> 1) My teacher told me that DNA only produces proteins, and I always 
> thought that it created the WHOLE body and was the design. What is the
> truth?
> 2) I know about DNA replication, but can someone go into the process a little
> further and explain DNA and RNA?
> 3) I have been told that DNA is the same in ALL species of organisms, if this
> is true, why can't we replicate or change an organism yet?
>    Overall, can someone explain what DNA really does, and is? Thanks! 
> David Levinson

Hi. Here are some answers to your questions.

Yes, DNA codes only for proteins. However it is not the sole determinant of
how an organism functions. The way in which the proteins interact with the
environment also affects the outcome of the organism. This is especially
important during development when environmental factors combine with
genetic factors to determine the outcome of the organism.

DNA can be thought of as the original or master blueprint of your genes. It
is found only in the nucleus of cell. When a cell needs a particular
protein, it copies the relevant information from the DNA in the nucleus
into an RNA analog. This is like you going into a library and photocopying
a relevant page out of a book. The DNA is like the entire library and the
photocopy is like the RNA. The RNA molecule is then transported out of the
nucleus and to the cytoplasm. In the cytoplasm, proteins called ribosomes
translate the RNA sequence into a protein sequence. 

There are important molecular differences between DNA and RNA. In DNA there
is no hydroxy group on the 2' ribose carbon. However in RNA there is a
hydroxy group at the 2' carbon. This makes DNA more stable than RNA,
allowing the cell to easily degrade RNA in the cytoplasm when the cell is
done making the necessary protein from the RNA. Also, while DNA's code
consists of adenenine, guanine, cytosine, and thymine nucleotide residues,
RNA substitutes uracil for thymine. There are other more complicated
differences between DNA and RNA but the two I mentioned above are basic.

Yes, DNA is the same in nearly all organisms and we can indeed change
organisms using genetic engineering. For example, the gene for insulin can
be spliced out of one organism and inserted into bacterial chromosomes.
Thus, you can grow bacteria which contain the insulin gene and produce
insulin for human use.

Hope this helps.


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