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Only 1 of 24 DNA strands used?

Larry Farrell farrlarr at isu.edu
Tue Jul 24 13:17:15 EST 2001

Ron Newman wrote:

> I recently heard the statement "only 1 of  24 'strands' of  human DNA
> actively used".
> a)  Is this accurate?
> b) Is there a good reference on it?
> c) If true, are the 23 unused portions simply redundant systems, are they
> mutated, or do they
> have other potential function?

You have posted this question several times without receiving any replies.
In my opinion, the reason for the lack of response is related to a major lack
of understanding of biology (human and otherwise) indicated in your post, on
both the part of the person who made the statement to you and on your part.
A complete reply would (apparently) require a complete course in biology,
which no one is willing to provide.  Let me hit only the highest of the high
points related to your question, leaving filling in of the details to you,
either by studying some basic biology texts or by asking questions of your
local high school or college biology teacher.

Human cells, except for germ (reproductive) cells, contain 23 pairs of
chromosome, with each chromosome consisting of 2 strands of DNA, thus there
are not 24 strands of DNA in a human cell but 46.  For each gene in each
chromosome, only one strand of the DNA comprising the gene is expressed, with
the other strand being used primarily to dictate what sequence of bases
should be linked together to make a new "active" strand when the DNA is
replicated.  The active strand is not the same strand throughout a given
chromosome.  That is, for adjacent genes, opposite strands may be expressed.

In a very small nutshell, then, the original statement made to you makes
absolutely no sense at all, for the reasons cited above and explained in much
greater detail in a huge number of basic biology books available in any

Larry D. Farrell, Ph.D.
Professor of Microbiology
Idaho State University

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