Mon Mar 21 09:04:13 EST 1994

David writes:

Mail from: David Levinson     +
To: bioforum at net.bio.net
From: dlevins at eis.calstate.edu (David Levinson)
Subject: DNA
Date: 20 Mar 1994 20:32:26 -0800

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
2) I know about DNA replication, but can someone go into the process a
further and explain DNA and RNA?
3) I have been told that DNA is the same in ALL species of organisms, if
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


David -
DNA does indeed encode the design of what you call the "whole" body; but as you
are apprently aware, the whole body is not just one big lump of protein.
Consider what you know about proteins for a moment; how many different
kinds of protein can you think of?

There are proteins which you may find on your plate in the form of chicken
meat, or beef protein - these are STRUCTURAL proteins (what your muscles are
made of).  There is another equally important type of protein- proteins that
do "work" or "labor" in the chemical sense - FUNCTIONAL proteins -
they may send a message or material across a cell membrane, or perhaps they are
involved in making a new molecule from two others, or break up one molecule
into two.  These proteins are involved in the making of a body.  For example,
bones are "sort of" deposited.  An example of this might be a house.  If you
think in terms of a plan for a house.  Ideas on paper, a blueprint.  These
ideas are transcibed into a foreman's mind as he reads them, just as
information is transcribed into protein from DNA.  Now this
foreman has to have workers, which while on the site, spend their time
putting bits and pieces together to form a house.  So if someone asked you
what the blueprints do, you'd say "Store information for a house".  If
the foreman and workers are proteins, when they are finished with the job, they
are not found as parts of the structure of the building.  Where do the parts
of the house come from? Usually by tractor-trailer, or in the case of a body,
through the mouth.

This is a very simplified analogy.

DNA is the same for all species only in the same way that all messages sent
by morse code are the same - all messages contain dots and dashes in a row.
All DNA is made of sugars, phosphates and special molecules call
NUCLEIC ACIDS (acids found in the nucleus), of which there are 4
types; for now, we'll just call them A,T,C and G.  The sequence
of a morse code is its information content- a message might say:

"Help!", or: "Your left foot is afire!", or: "My, isn't it wonderful
that student can post questions to bioforum and recieve helpful and
appropriate responses", or anything you cna think of.  The message
from DNA might say:
"ATCGCGTATGACATGATGCA...", or any sequence imaginable. The sequence of
nucleic acid molecules determines what protein will be made. We thereofore
do not expect all species' DNA to be the same, especially in the face of
evolution, which can work to keep new changes in the DNA sequence.

Think long and hard about this, David, and keep asking questions!

James Lyons-Weiler

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