What is a Gene, Heres the answer!

Marty Sachs msachs at UIUC.EDU
Tue Feb 22 09:26:05 EST 1994


In article <1994Feb21.160229.21462 at galileo.cc.rochester.edu>
>Absolutely.  There are many genes that do not lead to a protein product,
>ribozymes in addition to those Przemko has listed above.  I also must add the
>point I made before; that all cis-acting sequences (promotors, enhancers)
>should be included in the definition of a gene as well as the actual coding
>sequence.  Looking back to the notes from my Eucaryotic Genome class, I found
>what I think is a great definition.  Hope my Professor doesn't mind:
>
>     A gene is defined as all of the cis-acting nucleic acid
>     sequences required for the production of a functional RNA.
>
>                                             -M. Gorovsky
>
>How about that?

In prokaryotes, how many genes in the trp operon?  By this defination only one
(it encodes a single functional RNA, but 10 polypeptides are encoded in this
polycistronic mRNA), however most would argue that there are ten genes.  In
Eukaryotes, what would you call the 'unit' that encodes a product that results
from 'trans-splicing' (i.e., spicing between primary transcripts encoded by
'unlinked' transcription units to result in a single 'functional RNA)?  If the
'unit' encoding a 'funtional' RNA is a gene, then 'cis' must be taken out of
the defination.  How about when a single transcription unit encodes two or mor
e
'functional RNAs' after alternative splicing?  Only one gene, or is each
functional RNA encoded by its own gene?

Marty Sachs
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